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docs/topics/settings.rst
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.. _topics-settings:

========
Settings
========

The Scrapy settings allows you to customize the behaviour of all Scrapy
components, including the core, extensions, pipelines and spiders themselves.

The infrastructure of the settings provides a global namespace of key-value mappings
that the code can use to pull configuration values from. The settings can be
populated through different mechanisms, which are described below.

The settings are also the mechanism for selecting the currently active Scrapy
project (in case you have many).

For a list of available built-in settings see: :ref:`topics-settings-ref`.

.. _topics-settings-module-envvar:

Designating the settings
========================

When you use Scrapy, you have to tell it which settings you're using. You can
do this by using an environment variable, ``SCRAPY_SETTINGS_MODULE``.

The value of ``SCRAPY_SETTINGS_MODULE`` should be in Python path syntax, e.g.
``myproject.settings``. Note that the settings module should be on the
Python :ref:`import search path <tut-searchpath>`.

.. _populating-settings:

Populating the settings
=======================

Settings can be populated using different mechanisms, each of which has a
different precedence:

 1. :ref:`Command-line settings <cli-settings>` (highest precedence)
 2. :ref:`Spider settings <spider-settings>`
 3. :ref:`Project settings <project-settings>`
 4. :ref:`Add-on settings <addon-settings>`
 5. :ref:`Command-specific default settings <cmd-default-settings>`
 6. :ref:`Global default settings <default-settings>` (lowest precedence)

.. _cli-settings:

1. Command-line settings
------------------------

Settings set in the command line have the highest precedence, overriding any
other settings.

You can explicitly override one or more settings using the ``-s`` (or
``--set``) command-line option.

.. highlight:: sh

Example::

    scrapy crawl myspider -s LOG_LEVEL=INFO -s LOG_FILE=scrapy.log

.. _spider-settings:

2. Spider settings
------------------

:ref:`Spiders <topics-spiders>` can define their own settings that will take
precedence and override the project ones.

.. note:: :ref:`Pre-crawler settings <pre-crawler-settings>` cannot be defined
    per spider, and :ref:`reactor settings <reactor-settings>` and
    :ref:`logging settings <logging-settings>` are subject to restrictions when
    :ref:`running multiple spiders in the same process
    <run-multiple-spiders>`.

One way to do so is by setting their :attr:`~scrapy.Spider.custom_settings`
attribute:

.. code-block:: python

    import scrapy


    class MySpider(scrapy.Spider):
        name = "myspider"

        custom_settings = {
            "SOME_SETTING": "some value",
        }

It's often better to implement :meth:`~scrapy.Spider.update_settings` instead,
and settings set there should use the ``"spider"`` priority explicitly:

.. code-block:: python

    import scrapy


    class MySpider(scrapy.Spider):
        name = "myspider"

        @classmethod
        def update_settings(cls, settings):
            super().update_settings(settings)
            settings.set("SOME_SETTING", "some value", priority="spider")

.. versionadded:: 2.11

It's also possible to modify the settings in the
:meth:`~scrapy.Spider.from_crawler` method, e.g. based on :ref:`spider
arguments <spiderargs>` or other logic:

.. code-block:: python

    import scrapy


    class MySpider(scrapy.Spider):
        name = "myspider"

        @classmethod
        def from_crawler(cls, crawler, *args, **kwargs):
            spider = super().from_crawler(crawler, *args, **kwargs)
            if "some_argument" in kwargs:
                spider.settings.set(
                    "SOME_SETTING", kwargs["some_argument"], priority="spider"
                )
            return spider

.. _project-settings:

3. Project settings
-------------------

Scrapy projects include a settings module, usually a file called
``settings.py``, where you should populate most settings that apply to all your
spiders.

.. seealso:: :ref:`topics-settings-module-envvar`

.. _addon-settings:

4. Add-on settings
------------------

:ref:`Add-ons <topics-addons>` can modify settings. They should do this with
``"addon"`` priority where possible.

.. _cmd-default-settings:

5. Command-specific default settings
------------------------------------

Each :ref:`Scrapy command <topics-commands>` can have its own default settings,
which override the :ref:`global default settings <default-settings>`.

Those command-specific default settings are specified in the
``default_settings`` attribute of each command class.

.. _default-settings:

6. Default global settings
--------------------------

The ``scrapy.settings.default_settings`` module defines global default values
for some :ref:`built-in settings <topics-settings-ref>`.

.. note:: :command:`startproject` generates a ``settings.py`` file that sets
    some settings to different values.

    The reference documentation of settings indicates the default value if one
    exists. If :command:`startproject` sets a value, that value is documented
    as default, and the value from ``scrapy.settings.default_settings`` is
    documented as “fallback”.


Compatibility with pickle
=========================

Setting values must be :ref:`picklable <pickle-picklable>`.

Import paths and classes
========================

When a setting references a callable object to be imported by Scrapy, such as a
class or a function, there are two different ways you can specify that object:

-   As a string containing the import path of that object

-   As the object itself

For example:

.. skip: next
.. code-block:: python

   from mybot.pipelines.validate import ValidateMyItem

   ITEM_PIPELINES = {
       # passing the classname...
       ValidateMyItem: 300,
       # ...equals passing the class path
       "mybot.pipelines.validate.ValidateMyItem": 300,
   }

.. note:: Passing non-callable objects is not supported.


How to access settings
======================

.. highlight:: python

In a spider, settings are available through ``self.settings``:

.. code-block:: python

    class MySpider(scrapy.Spider):
        name = "myspider"
        start_urls = ["http://example.com"]

        def parse(self, response):
            print(f"Existing settings: {self.settings.attributes.keys()}")

.. note::
    The ``settings`` attribute is set in the base Spider class after the spider
    is initialized.  If you want to use settings before the initialization
    (e.g., in your spider's ``__init__()`` method), you'll need to override the
    :meth:`~scrapy.Spider.from_crawler` method.

:ref:`Components <topics-components>` can also :ref:`access settings
<component-settings>`.

The ``settings`` object can be used like a :class:`dict` (e.g.
``settings["LOG_ENABLED"]``). However, to support non-string setting values,
which may be passed from the command line as strings, it is recommended to use
one of the methods provided by the :class:`~scrapy.settings.Settings` API.


.. _component-priority-dictionaries:

Component priority dictionaries
===============================

A **component priority dictionary** is a :class:`dict` where keys are
:ref:`components <topics-components>` and values are component priorities. For
example:

.. skip: next
.. code-block:: python

    {
        "path.to.ComponentA": None,
        ComponentB: 100,
    }

A component can be specified either as a class object or through an import
path.

.. warning:: Component priority dictionaries are regular :class:`dict` objects.
    Be careful not to define the same component more than once, e.g. with
    different import path strings or defining both an import path and a
    :class:`type` object.

A priority can be an :class:`int` or :data:`None`.

A component with priority 1 goes *before* a component with priority 2. What
going before entails, however, depends on the corresponding setting. For
example, in the :setting:`DOWNLOADER_MIDDLEWARES` setting, components have
their
:meth:`~scrapy.downloadermiddlewares.DownloaderMiddleware.process_request`
method executed before that of later components, but have their
:meth:`~scrapy.downloadermiddlewares.DownloaderMiddleware.process_response`
method executed after that of later components.

A component with priority :data:`None` is disabled.

Some component priority dictionaries get merged with some built-in value. For
example, :setting:`DOWNLOADER_MIDDLEWARES` is merged with
:setting:`DOWNLOADER_MIDDLEWARES_BASE`. This is where :data:`None` comes in
handy, allowing you to disable a component from the base setting in the regular
setting:

.. code-block:: python

    DOWNLOADER_MIDDLEWARES = {
        "scrapy.downloadermiddlewares.offsite.OffsiteMiddleware": None,
    }


Special settings
================

The following settings work slightly differently than all other settings.

.. _pre-crawler-settings:

Pre-crawler settings
--------------------

**Pre-crawler settings** are settings used before the
:class:`~scrapy.crawler.Crawler` object is created.

These settings cannot be :ref:`set from a spider <spider-settings>`.

These settings are:

-   :setting:`ADDONS`
-   :setting:`COMMANDS_MODULE`
-   :setting:`FORCE_CRAWLER_PROCESS`
-   :setting:`SPIDER_LOADER_CLASS` and settings used by the corresponding
    spider loader class, e.g. :setting:`SPIDER_MODULES` and
    :setting:`SPIDER_LOADER_WARN_ONLY` for the default spider loader class.
-   :setting:`TWISTED_REACTOR_ENABLED`

:setting:`ADDONS` is a special case: it can be set from a spider, but the
``update_pre_crawler_settings()`` method of :ref:`add-ons <topics-addons>`
enabled that way is not called.

:setting:`TWISTED_REACTOR` also acts as a pre-crawler setting when running a
:ref:`command that needs a CrawlerProcess <topics-commands-crawlerprocess>`,
since its project-level value determines the crawler process class.

.. _reactor-settings:

Reactor settings
----------------

**Reactor settings** are settings tied to the :doc:`Twisted reactor
<twisted:core/howto/reactor-basics>`.

Because only 1 reactor can be used per process, these settings cannot use a
different value per spider when :ref:`running multiple spiders in the same
process <run-multiple-spiders>`.

These settings are used upon installing the reactor:

-   :setting:`ASYNCIO_EVENT_LOOP` (not possible to set per-spider when using
    :class:`~scrapy.crawler.AsyncCrawlerProcess`, see below)

-   :setting:`TWISTED_REACTOR` (ignored when using
    :class:`~scrapy.crawler.AsyncCrawlerProcess`, see below)

They can be :ref:`set from a spider <spider-settings>`, but only the values
from the first spider that runs are used, since that is when the reactor is
installed. If a later spider asks for a different reactor or a different event
loop, an exception is raised. With
:class:`~scrapy.crawler.CrawlerRunner` and
:class:`~scrapy.crawler.AsyncCrawlerRunner` the reactor must be installed
beforehand, so these settings are only used to check that the installed reactor
and event loop match them.

These settings are applied when starting the reactor:

-   :setting:`TWISTED_DNS_RESOLVER` and settings used by the corresponding
    component, e.g. :setting:`DNSCACHE_ENABLED`, :setting:`DNSCACHE_SIZE`
    and :setting:`DNS_TIMEOUT` for the default one.

-   :setting:`REACTOR_THREADPOOL_MAXSIZE`

They are read from the settings of the
:class:`~scrapy.crawler.CrawlerProcess` or
:class:`~scrapy.crawler.AsyncCrawlerProcess` object, so setting them from a
spider or an :ref:`add-on <topics-addons>` has no effect. They are ignored
altogether when using :class:`~scrapy.crawler.CrawlerRunner` or
:class:`~scrapy.crawler.AsyncCrawlerRunner`, which do not start the reactor.

There is an additional restriction for :setting:`TWISTED_REACTOR` and
:setting:`ASYNCIO_EVENT_LOOP` when using
:class:`~scrapy.crawler.AsyncCrawlerProcess`: when this class is instantiated,
it installs :class:`~twisted.internet.asyncioreactor.AsyncioSelectorReactor`,
ignoring the value of :setting:`TWISTED_REACTOR` and using the value of
:setting:`ASYNCIO_EVENT_LOOP` that was passed to
:meth:`AsyncCrawlerProcess.__init__()
<scrapy.crawler.AsyncCrawlerProcess.__init__>`. If a different value for
:setting:`TWISTED_REACTOR` or :setting:`ASYNCIO_EVENT_LOOP` is provided later,
e.g. in :ref:`per-spider settings <spider-settings>`, an exception will be
raised.

All of these settings, except for :setting:`ASYNCIO_EVENT_LOOP`, are only used
when the Twisted reactor is used, i.e. when :setting:`TWISTED_REACTOR_ENABLED`
is ``True``.

.. _logging-settings:

Logging settings
----------------

**Logging settings** are settings that configure the global root logging
handler installed by :func:`~scrapy.utils.log.configure_logging`.

These settings can be defined from a spider. However, because only 1 root
logging handler is active per process, these settings cannot use a different
value per spider when :ref:`running multiple spiders in the same process
<run-multiple-spiders>`.

These settings are:

-   :setting:`LOG_DATEFORMAT`
-   :setting:`LOG_ENABLED`
-   :setting:`LOG_ENCODING`
-   :setting:`LOG_FILE`
-   :setting:`LOG_FILE_APPEND`
-   :setting:`LOG_FORMAT`
-   :setting:`LOG_LEVEL`
-   :setting:`LOG_SHORT_NAMES`
-   :setting:`LOG_STDOUT`

.. _topics-settings-ref:

Built-in settings reference
===========================

Here's a list of all available Scrapy settings, in alphabetical order, along
with their default values and the scope where they apply.

The scope, where available, shows where the setting is being used, if it's tied
to any particular component. In that case the module of that component will be
shown, typically an extension, middleware or pipeline. It also means that the
component must be enabled in order for the setting to have any effect.

.. setting:: ADDONS

ADDONS
------

Default: ``{}``

A dict containing paths to the add-ons enabled in your project and their
priorities. For more information, see :ref:`topics-addons`.

.. note:: This is a :ref:`pre-crawler setting <pre-crawler-settings>`, with a
    caveat described in that section.

.. setting:: ASYNCIO_EVENT_LOOP

ASYNCIO_EVENT_LOOP
------------------

Default: ``None``

Import path of a given ``asyncio`` event loop class.

If the asyncio reactor is enabled (see :setting:`TWISTED_REACTOR`) or when
:ref:`running Scrapy without a reactor <asyncio-without-reactor>` this setting
can be used to specify the
asyncio event loop to be used with it. Set the setting to the import path of the
desired asyncio event loop class. If the setting is set to ``None`` the default asyncio
event loop will be used.

If you are installing the asyncio reactor manually using the :func:`~scrapy.utils.reactor.install_reactor`
function, you can use the ``event_loop_path`` parameter to indicate the import path of the event loop
class to be used.

Note that the event loop class must inherit from :class:`asyncio.AbstractEventLoop`.

.. caution:: Please be aware that, when using a non-default event loop
    (either defined via :setting:`ASYNCIO_EVENT_LOOP` or installed with
    :func:`~scrapy.utils.reactor.install_reactor`), Scrapy will call
    :func:`asyncio.set_event_loop`, which will set the specified event loop
    as the current loop for the current OS thread.

.. note:: This is a :ref:`reactor setting <reactor-settings>`.

.. setting:: AWS_ACCESS_KEY_ID

AWS_ACCESS_KEY_ID
-----------------

Default: ``None``

The AWS access key used by code that requires access to `Amazon Web services`_,
such as the :ref:`S3 feed storage backend <topics-feed-storage-s3>`.

.. setting:: AWS_ENDPOINT_URL

AWS_ENDPOINT_URL
----------------

Default: ``None``

Endpoint URL used for S3-like storage, for example Minio or s3.scality.

.. setting:: AWS_MAX_POOL_CONNECTIONS

AWS_MAX_POOL_CONNECTIONS
------------------------

.. versionadded:: VERSION

Default: ``None``

Maximum number of connections that AWS clients, such as those of the
:ref:`S3 feed storage backend <topics-feed-storage-s3>` and of the
:ref:`S3 media pipeline storage backend <media-pipelines-s3>`, keep in their
connection pool.

If ``None``, the value of :setting:`REACTOR_THREADPOOL_MAXSIZE` is used.

Values lower than the number of parallel AWS calls do not limit those calls, but
their connections are closed instead of reused, which hurts performance, and
``Connection pool is full, discarding connection`` warnings are logged.

.. setting:: AWS_REGION_NAME

AWS_REGION_NAME
---------------

Default: ``None``

The name of the region associated with the AWS client.

.. setting:: AWS_SECRET_ACCESS_KEY

AWS_SECRET_ACCESS_KEY
---------------------

Default: ``None``

The AWS secret key used by code that requires access to `Amazon Web services`_,
such as the :ref:`S3 feed storage backend <topics-feed-storage-s3>`.

.. setting:: AWS_SESSION_TOKEN

AWS_SESSION_TOKEN
-----------------

Default: ``None``

The AWS security token used by code that requires access to `Amazon Web services`_,
such as the :ref:`S3 feed storage backend <topics-feed-storage-s3>`, when using
`temporary security credentials`_.

.. _temporary security credentials: https://docs.aws.amazon.com/IAM/latest/UserGuide/security-creds.html

.. setting:: AWS_USE_SSL

AWS_USE_SSL
-----------

Default: ``None``

Use this option if you want to disable SSL connection for communication with
S3 or S3-like storage. By default SSL will be used.

.. setting:: AWS_VERIFY

AWS_VERIFY
----------

Default: ``None``

Verify SSL connection between Scrapy and S3 or S3-like storage. By default
SSL verification will occur.

.. setting:: BOT_NAME

BOT_NAME
--------

Default: ``<project name>`` (:ref:`fallback <default-settings>`: ``'scrapybot'``)

The name of the bot implemented by this Scrapy project (also known as the
project name). This name will be used for the logging too.

It's automatically populated with your project name when you create your
project with the :command:`startproject` command.

.. setting:: CONCURRENT_ITEMS

CONCURRENT_ITEMS
----------------

Default: ``100``

Maximum number of concurrent items (per response) to process in parallel in
:ref:`item pipelines <topics-item-pipeline>`.

.. setting:: CONCURRENT_REQUESTS

CONCURRENT_REQUESTS
-------------------

Default: ``16``

The maximum number of concurrent (i.e. simultaneous) requests that will be
performed by the Scrapy downloader. Use ``0`` for no limit.

.. setting:: CONCURRENT_REQUESTS_PER_DOMAIN

CONCURRENT_REQUESTS_PER_DOMAIN
------------------------------

Default: ``1`` (:ref:`fallback <default-settings>`: ``8``)

The maximum number of concurrent (i.e. simultaneous) requests that will be
performed to any single domain.

See also: :ref:`topics-autothrottle` and its
:setting:`AUTOTHROTTLE_TARGET_CONCURRENCY` option.

It is possible to change this setting per domain by using
:setting:`DOWNLOAD_SLOTS`.

.. setting:: DEFAULT_DROPITEM_LOG_LEVEL

DEFAULT_DROPITEM_LOG_LEVEL
--------------------------

Default: ``"WARNING"``

Default :ref:`log level <levels>` of messages about dropped items.

When an item is dropped by raising :exc:`scrapy.exceptions.DropItem` from the
:func:`process_item` method of an :ref:`item pipeline <topics-item-pipeline>`,
a message is logged, and by default its log level is the one configured in this
setting.

You may specify this log level as an integer (e.g. ``20``), as a log level
constant (e.g. ``logging.INFO``) or as a string with the name of a log level
constant (e.g. ``"INFO"``).

When writing an item pipeline, you can force a different log level by setting
:attr:`scrapy.exceptions.DropItem.log_level` in your
:exc:`scrapy.exceptions.DropItem` exception. For example:

.. code-block:: python

   from scrapy.exceptions import DropItem


   class MyPipeline:
       def process_item(self, item):
           if not item.get("price"):
               raise DropItem("Missing price data", log_level="INFO")
           return item

.. setting:: DEFAULT_ITEM_CLASS

DEFAULT_ITEM_CLASS
------------------

Default: ``'scrapy.item.Item'``

The default class that will be used for instantiating items in the :ref:`the
Scrapy shell <topics-shell>`.

.. setting:: DEFAULT_REQUEST_HEADERS

DEFAULT_REQUEST_HEADERS
-----------------------

Default:

.. code-block:: python

    {
        "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
        "Accept-Language": "en",
    }

The default headers used for Scrapy HTTP Requests. They're populated in the
:class:`~scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware`.

.. caution:: Cookies set via the ``Cookie`` header are not considered by the
    :ref:`cookie middleware <cookies>`. If you need to set cookies for a
    request, use the :class:`Request.cookies <scrapy.Request>` parameter.

.. caution:: A ``Referer`` header defined here only reaches requests for which
    :class:`~scrapy.spidermiddlewares.referer.RefererMiddleware` does not set
    one, such as start requests. To send it on every request, set
    :setting:`REFERRER_POLICY` to ``"no-referrer"``.

.. setting:: DEPTH_LIMIT

DEPTH_LIMIT
-----------

Default: ``0``

Scope: ``scrapy.spidermiddlewares.depth.DepthMiddleware``

The maximum depth that will be allowed to crawl for any site. If zero, no limit
will be imposed.

.. setting:: DEPTH_PRIORITY

DEPTH_PRIORITY
--------------

Default: ``0``

Scope: ``scrapy.spidermiddlewares.depth.DepthMiddleware``

An integer that is used to adjust the :attr:`~scrapy.Request.priority` of
a :class:`~scrapy.Request` based on its depth.

The priority of a request is adjusted as follows:

.. skip: next
.. code-block:: python

    request.priority = request.priority - (depth * DEPTH_PRIORITY)

As depth increases, positive values of ``DEPTH_PRIORITY`` decrease request
priority (BFO), while negative values increase request priority (DFO). See
also :ref:`faq-bfo-dfo`.

.. note::

    This setting adjusts priority **in the opposite way** compared to
    other priority settings :setting:`REDIRECT_PRIORITY_ADJUST`
    and :setting:`RETRY_PRIORITY_ADJUST`.

.. setting:: DEPTH_STATS_VERBOSE

DEPTH_STATS_VERBOSE
-------------------

Default: ``False``

Scope: ``scrapy.spidermiddlewares.depth.DepthMiddleware``

Whether to collect verbose depth stats. If this is enabled, the number of
requests for each depth is collected in the stats.

.. setting:: DNSCACHE_ENABLED

DNSCACHE_ENABLED
----------------

Default: ``True``

Whether to enable DNS in-memory cache.

.. note::
    This setting is only used by
    :class:`~scrapy.resolver.CachingThreadedResolver` and
    :class:`~scrapy.resolver.CachingHostnameResolver`. It has no effect when
    :setting:`TWISTED_REACTOR_ENABLED` is ``False``, and may have no effect
    either when :setting:`TWISTED_DNS_RESOLVER` is set to a different resolver.

.. note:: This is a :ref:`reactor setting <reactor-settings>`.

.. setting:: DNSCACHE_SIZE

DNSCACHE_SIZE
-------------

Default: ``10000``

DNS in-memory cache size, see :setting:`DNSCACHE_ENABLED`.

.. note:: This is a :ref:`reactor setting <reactor-settings>`.

.. setting:: DNS_TIMEOUT

DNS_TIMEOUT
-----------

Default: ``60``

Timeout for processing of DNS queries in seconds. Float is supported.

The timeout starts when the query is queued into the Twisted reactor thread
pool, not when it is sent. If that thread pool is saturated, queries can time
out before being sent, in which case increasing
:setting:`REACTOR_THREADPOOL_MAXSIZE` helps more than increasing this setting.

.. note::
    This setting is only used by
    :class:`~scrapy.resolver.CachingThreadedResolver`. It has no effect when
    :setting:`TWISTED_REACTOR_ENABLED` is ``False``, and may have no effect
    either when :setting:`TWISTED_DNS_RESOLVER` is set to a different resolver.

.. note:: This is a :ref:`reactor setting <reactor-settings>`.

.. setting:: DOWNLOADER

DOWNLOADER
----------

Default: ``'scrapy.core.downloader.Downloader'``

The downloader to use for crawling.

.. setting:: DOWNLOADER_CLIENT_TLS_CIPHERS

DOWNLOADER_CLIENT_TLS_CIPHERS
-----------------------------

Default: ``'DEFAULT'``

Use this setting to customize the TLS/SSL ciphers used by the HTTPS download
handler.

The setting should contain a string in the `OpenSSL cipher list format`_,
these ciphers will be used as client ciphers. Changing this setting may be
necessary to access certain HTTPS websites: for example, you may need to use
``'DEFAULT:!DH'`` for a website with weak DH parameters or enable a
specific cipher that is not included in ``DEFAULT`` if a website requires it.

Set this setting to ``None`` to use the default ciphers of the underlying TLS
implementation.

.. versionchanged:: 2.17.0
   Added support for setting this to ``None``.

.. _OpenSSL cipher list format: https://docs.openssl.org/master/man1/openssl-ciphers/#cipher-list-format

.. note::

    Handling of this setting needs to be implemented inside the :ref:`download
    handler <topics-download-handlers>`, so it's not guaranteed to be supported
    by all 3rd-party handlers.

.. seealso:: :ref:`security-tls-protocols-ciphers`

.. setting:: DOWNLOAD_TLS_MAX_VERSION

DOWNLOAD_TLS_MAX_VERSION
------------------------

.. versionadded:: 2.17.0

Default: ``None``

Use this setting to change the maximum version of the TLS protocol allowed to
be used by Scrapy.

This setting must be either ``None``, in which case it doesn't affect the
version selection, or one of these string values:

- ``'TLSv1.0'``
- ``'TLSv1.1'``
- ``'TLSv1.2'``
- ``'TLSv1.3'``

The range of allowed TLS versions advertised by Scrapy when making TLS
connections will depend on the TLS implementation defaults and the values of
:setting:`DOWNLOAD_TLS_MIN_VERSION` and :setting:`DOWNLOAD_TLS_MAX_VERSION`.
It's possible to re-enable versions that are supported by the TLS
implementation but disabled by default by adjusting these settings, but it's
impossible to enable unsupported ones, such as any versions below 1.2 in many
modern environments.

.. note::

    Handling of this setting needs to be implemented inside the :ref:`download
    handler <topics-download-handlers>`, so it's not guaranteed to be supported
    by all 3rd-party handlers. Additionally, the set of supported TLS versions
    depends on the TLS implementation being used by the handler.

.. seealso:: :ref:`security-tls-protocols-ciphers`

.. setting:: DOWNLOAD_TLS_MIN_VERSION

DOWNLOAD_TLS_MIN_VERSION
------------------------

.. versionadded:: 2.17.0

Default: ``None``

Use this setting to change the minimum version of the TLS protocol allowed to
be used by Scrapy.

See :setting:`DOWNLOAD_TLS_MAX_VERSION` for the details and limitations.

.. seealso:: :ref:`security-tls-protocols-ciphers`

.. setting:: DOWNLOADER_CLIENT_TLS_VERBOSE_LOGGING

DOWNLOADER_CLIENT_TLS_VERBOSE_LOGGING
-------------------------------------

Default: ``False``

Setting this to ``True`` will enable DEBUG level messages about TLS connection
parameters after establishing HTTPS connections. The kind of information logged
depends on the implementation of the download handler and the versions of
the TLS-related libraries.

.. note::

    Handling of this setting needs to be implemented inside the :ref:`download
    handler <topics-download-handlers>`, so it's not guaranteed to be supported
    by all 3rd-party handlers.

.. setting:: DOWNLOADER_MIDDLEWARES

DOWNLOADER_MIDDLEWARES
----------------------

Default: ``{}``

A dict containing the downloader middlewares enabled in your project, and their
orders. For more info see :ref:`topics-downloader-middleware-setting`.

.. setting:: DOWNLOADER_MIDDLEWARES_BASE

DOWNLOADER_MIDDLEWARES_BASE
---------------------------

Default:

.. code-block:: python

    {
        "scrapy.downloadermiddlewares.offsite.OffsiteMiddleware": 50,
        "scrapy.downloadermiddlewares.robotstxt.RobotsTxtMiddleware": 100,
        "scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware": 300,
        "scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware": 350,
        "scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware": 400,
        "scrapy.downloadermiddlewares.useragent.UserAgentMiddleware": 500,
        "scrapy.downloadermiddlewares.retry.RetryMiddleware": 550,
        "scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware": 580,
        "scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware": 590,
        "scrapy.downloadermiddlewares.redirect.RedirectMiddleware": 600,
        "scrapy.downloadermiddlewares.cookies.CookiesMiddleware": 700,
        "scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware": 750,
        "scrapy.downloadermiddlewares.stats.DownloaderStats": 850,
        "scrapy.downloadermiddlewares.httpcache.HttpCacheMiddleware": 900,
    }

A dict containing the downloader middlewares enabled by default in Scrapy. Low
orders are closer to the engine, high orders are closer to the downloader. You
should never modify this setting in your project, modify
:setting:`DOWNLOADER_MIDDLEWARES` instead.  For more info see
:ref:`topics-downloader-middleware-setting`.

.. setting:: DOWNLOADER_STATS

DOWNLOADER_STATS
----------------

Default: ``True``

Whether to enable downloader stats collection.

.. setting:: DOWNLOAD_DELAY

DOWNLOAD_DELAY
--------------

Default: ``1`` (:ref:`fallback <default-settings>`: ``0``)

Minimum seconds to wait between 2 consecutive requests to the same domain.

Use :setting:`DOWNLOAD_DELAY` to throttle your crawling speed, to avoid hitting
servers too hard.

Decimal numbers are supported. For example, to send a maximum of 4 requests
every 10 seconds:

.. code-block:: python

    DOWNLOAD_DELAY = 2.5

This setting is also affected by the :setting:`RANDOMIZE_DOWNLOAD_DELAY`
setting, which is enabled by default.

Note that :setting:`DOWNLOAD_DELAY` can lower the effective per-domain
concurrency below :setting:`CONCURRENT_REQUESTS_PER_DOMAIN`. If the response
time of a domain is lower than :setting:`DOWNLOAD_DELAY`, the effective
concurrency for that domain is 1. When testing throttling configurations, it
usually makes sense to lower :setting:`CONCURRENT_REQUESTS_PER_DOMAIN` first,
and only increase :setting:`DOWNLOAD_DELAY` once
:setting:`CONCURRENT_REQUESTS_PER_DOMAIN` is 1 but a higher throttling is
desired.

.. _spider-download_delay-attribute:

It is possible to change this setting per domain by using
:setting:`DOWNLOAD_SLOTS`.

.. setting:: DOWNLOAD_BIND_ADDRESS

DOWNLOAD_BIND_ADDRESS
---------------------

Default: ``None``

The default local outgoing address for download-handler connections.

This setting can be either:

- a host address as a string (e.g. ``"127.0.0.2"``), in which case the local
  port is chosen automatically, or

- a ``(host, port)`` tuple (e.g. ``("127.0.0.2", 50000)``) to bind to both a
  specific local interface and a specific local port.

For example:

.. code-block:: python

    # Bind to this local address
    DOWNLOAD_BIND_ADDRESS = "127.0.0.2"

.. code-block:: python

    # Bind to this local address and local port
    DOWNLOAD_BIND_ADDRESS = ("127.0.0.2", 5000)

If set, built-in HTTP download handlers use this value by default.
Set the :reqmeta:`bindaddress` request meta key to override it for a specific
request.

.. note::

    Handling of this setting needs to be implemented inside the :ref:`download
    handler <topics-download-handlers>`, so it's not guaranteed to be supported
    by all 3rd-party handlers. Specifying the port is unsupported by
    :class:`~scrapy.core.downloader.handlers._httpx.HttpxDownloadHandler`.

.. setting:: DOWNLOAD_HANDLERS

DOWNLOAD_HANDLERS
-----------------

Default: ``{}``

A dict containing the :ref:`download handlers <topics-download-handlers>`
enabled in your project.

See :setting:`DOWNLOAD_HANDLERS_BASE` for example format.

.. seealso:: :ref:`security-unencrypted-protocols` and
    :ref:`security-local-resources`

.. setting:: DOWNLOAD_HANDLERS_BASE

DOWNLOAD_HANDLERS_BASE
----------------------

Default:

.. code-block:: python

    {
        "data": "scrapy.core.downloader.handlers.datauri.DataURIDownloadHandler",
        "file": "scrapy.core.downloader.handlers.file.FileDownloadHandler",
        "http": "scrapy.core.downloader.handlers.http11.HTTP11DownloadHandler",
        "https": "scrapy.core.downloader.handlers.http11.HTTP11DownloadHandler",
        "s3": "scrapy.core.downloader.handlers.s3.S3DownloadHandler",
        "ftp": "scrapy.core.downloader.handlers.ftp.FTPDownloadHandler",
    }

(when :setting:`TWISTED_REACTOR_ENABLED` is ``True``)

.. code-block:: python

    {
        "data": "scrapy.core.downloader.handlers.datauri.DataURIDownloadHandler",
        "file": "scrapy.core.downloader.handlers.file.FileDownloadHandler",
        "http": "scrapy.core.downloader.handlers._httpx.HttpxDownloadHandler",
        "https": "scrapy.core.downloader.handlers._httpx.HttpxDownloadHandler",
        "s3": "scrapy.core.downloader.handlers.s3.S3DownloadHandler",
        "ftp": None,
    }

(when :setting:`TWISTED_REACTOR_ENABLED` is ``False``)

A dict containing the :ref:`download handlers <topics-download-handlers>`
enabled by default in Scrapy. You should never modify this setting in your
project, modify :setting:`DOWNLOAD_HANDLERS` instead.

You can disable any of these download handlers by assigning ``None`` to their
URI scheme in :setting:`DOWNLOAD_HANDLERS`. E.g., to disable the built-in FTP
handler (without replacement), place this in your ``settings.py``:

.. code-block:: python

    DOWNLOAD_HANDLERS = {
        "ftp": None,
    }

.. seealso:: :ref:`security-unencrypted-protocols` and
    :ref:`security-local-resources`


.. setting:: DOWNLOAD_SLOTS

DOWNLOAD_SLOTS
--------------

Default: ``{}``

Allows to define concurrency/delay parameters on per slot (domain) basis:

    .. code-block:: python

        DOWNLOAD_SLOTS = {
            "quotes.toscrape.com": {"concurrency": 1, "delay": 2, "randomize_delay": False},
            "books.toscrape.com": {"delay": 3, "randomize_delay": False},
        }

.. note::

    For other downloader slots default settings values will be used:

    -   :setting:`DOWNLOAD_DELAY`: ``delay``
    -   :setting:`CONCURRENT_REQUESTS_PER_DOMAIN`: ``concurrency``
    -   :setting:`RANDOMIZE_DOWNLOAD_DELAY`: ``randomize_delay``


.. setting:: DOWNLOAD_TIMEOUT

DOWNLOAD_TIMEOUT
----------------

Default: ``180``

The amount of time (in secs) that the downloader will wait before timing out.

.. note::

    This timeout can be per-request using the :reqmeta:`download_timeout`
    :attr:`.Request.meta` key.

.. note::

    Handling of this setting needs to be implemented inside the :ref:`download
    handler <topics-download-handlers>`, so it's not guaranteed to be supported
    by all 3rd-party handlers.

.. setting:: DOWNLOAD_MAXSIZE
.. reqmeta:: download_maxsize

DOWNLOAD_MAXSIZE
----------------

Default: ``1073741824`` (1 GiB)

The maximum response body size (in bytes) allowed. Bigger responses are
aborted and ignored.

This applies both before and after compression. If decompressing a response
body would exceed this limit, decompression is aborted and the response is
ignored.

Use ``0`` to disable this limit.

.. note::

    This limit can be set per-request using the :reqmeta:`download_maxsize`
    :attr:`.Request.meta` key.

.. note::

    Checking responses before decompressing them needs to be implemented inside
    the :ref:`download handler <topics-download-handlers>`, so it's not
    guaranteed to be supported by all 3rd-party handlers.

.. setting:: DOWNLOAD_WARNSIZE
.. reqmeta:: download_warnsize

DOWNLOAD_WARNSIZE
-----------------

Default: ``33554432`` (32 MiB)

If the size of a response exceeds this value, before or after compression, a
warning will be logged about it.

Use ``0`` to disable this limit.

.. note::

    This limit can be set per-request using the :reqmeta:`download_warnsize`
    :attr:`.Request.meta` key.

.. note::

    Checking responses before decompressing them needs to be implemented inside
    the :ref:`download handler <topics-download-handlers>`, so it's not
    guaranteed to be supported by all 3rd-party handlers.

.. setting:: DOWNLOAD_FAIL_ON_DATALOSS

DOWNLOAD_FAIL_ON_DATALOSS
-------------------------

Default: ``True``

Whether or not to fail on broken responses, that is, when the declared
``Content-Length`` does not match content sent by the server or a chunked
response was not properly finished. If ``True``, these responses raise a
:exc:`~scrapy.exceptions.ResponseDataLossError` exception. If ``False``, these
responses are passed through and the flag ``dataloss`` is added to the
response, i.e.: ``'dataloss' in response.flags`` is ``True``.

Optionally, this can be set per-request basis by using the
:reqmeta:`download_fail_on_dataloss` Request.meta key to ``False``.

.. note::

  A broken response, or data loss error, may happen under several
  circumstances, from server misconfiguration to network errors to data
  corruption. It is up to the user to decide if it makes sense to process
  broken responses considering they may contain partial or incomplete content.
  If :setting:`RETRY_ENABLED` is ``True`` and this setting is set to ``True``,
  the :exc:`~scrapy.exceptions.ResponseDataLossError` failure will be retried
  as usual.

.. note::

    Handling of this setting needs to be implemented inside the :ref:`download
    handler <topics-download-handlers>`, so it's not guaranteed to be supported
    by all 3rd-party handlers.

.. warning::

    This setting is ignored by the
    :class:`~scrapy.core.downloader.handlers.http2.H2DownloadHandler`
    :ref:`download handler <topics-download-handlers>`. In case of a data loss
    error, the corresponding HTTP/2 connection may be corrupted, affecting other
    requests that use the same connection; hence, a ``ResponseFailed([InvalidBodyLengthError])``
    failure is always raised for every request that was using that connection.

.. setting:: DOWNLOAD_VERIFY_CERTIFICATES

DOWNLOAD_VERIFY_CERTIFICATES
----------------------------

Default: ``False``

Whether the HTTPS download handlers should verify the server TLS certificate
when making a request and abort the request if the verification fails.

.. note::

    Handling of this setting needs to be implemented inside the :ref:`download
    handler <topics-download-handlers>`, so it's not guaranteed to be supported
    by all 3rd-party handlers. The exact behavior of a handler (e.g. whether
    certificate problems are logged when this setting is set to ``False``)
    depends on its implementation.

.. seealso:: :ref:`security-certificate-verification`

.. setting:: DUPEFILTER_CLASS

DUPEFILTER_CLASS
----------------

Default: ``'scrapy.dupefilters.RFPDupeFilter'``

The class used to detect and filter duplicate requests.

The default, :class:`~scrapy.dupefilters.RFPDupeFilter`, filters based on the
:setting:`REQUEST_FINGERPRINTER_CLASS` setting.

To change how duplicates are checked, you can point :setting:`DUPEFILTER_CLASS`
to a custom subclass of :class:`~scrapy.dupefilters.RFPDupeFilter` that
overrides its ``__init__`` method to use a :ref:`different request
fingerprinting class <custom-request-fingerprinter>`. For example:

.. code-block:: python

    from scrapy.dupefilters import RFPDupeFilter
    from scrapy.utils.request import fingerprint


    class CustomRequestFingerprinter:
        def fingerprint(self, request):
            return fingerprint(request, include_headers=["X-ID"])


    class CustomDupeFilter(RFPDupeFilter):

        def __init__(self, path=None, debug=False, *, fingerprinter=None):
            super().__init__(
                path=path, debug=debug, fingerprinter=CustomRequestFingerprinter()
            )

To disable duplicate request filtering set :setting:`DUPEFILTER_CLASS` to
``'scrapy.dupefilters.BaseDupeFilter'``. Note that not filtering out duplicate
requests may cause crawling loops. It is usually better to set
the ``dont_filter`` parameter to ``True`` on the ``__init__`` method of a
specific :class:`~scrapy.Request` object that should not be filtered out.

A class assigned to :setting:`DUPEFILTER_CLASS` must implement the following
interface:

.. code-block:: python

    class MyDupeFilter:

        @classmethod
        def from_crawler(cls, crawler):
            """Returns an instance of this duplicate request filtering class
            based on the current Crawler instance."""
            return cls()

        def request_seen(self, request):
            """Returns ``True`` if *request* is a duplicate of another request
            seen in a previous call to :meth:`request_seen`, or ``False``
            otherwise."""
            return False

        def open(self):
            """Called before the spider opens. It may return a deferred."""
            pass

        def close(self, reason):
            """Called before the spider closes. It may return a deferred."""
            pass

        def log(self, request, spider):
            """Logs that a request has been filtered out.

            It is called right after a call to :meth:`request_seen` that
            returns ``True``.

            If :meth:`request_seen` always returns ``False``, such as in the
            case of :class:`~scrapy.dupefilters.BaseDupeFilter`, this method
            may be omitted.
            """
            pass

.. autoclass:: scrapy.dupefilters.BaseDupeFilter

.. autoclass:: scrapy.dupefilters.RFPDupeFilter


.. setting:: DUPEFILTER_DEBUG

DUPEFILTER_DEBUG
----------------

Default: ``False``

By default, ``RFPDupeFilter`` only logs the first duplicate request.
Setting :setting:`DUPEFILTER_DEBUG` to ``True`` will make it log all duplicate requests.

.. setting:: EDITOR

EDITOR
------

Default: ``vi`` (on Unix systems) or the IDLE editor (on Windows)

The editor to use for editing spiders with the :command:`edit` command.
Additionally, if the ``EDITOR`` environment variable is set, the :command:`edit`
command will prefer it over the default setting.

.. setting:: EXTENSIONS

EXTENSIONS
----------

Default: ``{}``

:ref:`Component priority dictionary <component-priority-dictionaries>` of
enabled extensions. See :ref:`topics-extensions`.

.. setting:: EXTENSIONS_BASE

EXTENSIONS_BASE
---------------

Default:

.. code-block:: python

    {
        "scrapy.extensions.corestats.CoreStats": 0,
        "scrapy.extensions.logcount.LogCount": 0,
        "scrapy.extensions.telnet.TelnetConsole": 0,
        "scrapy.extensions.memusage.MemoryUsage": 0,
        "scrapy.extensions.memdebug.MemoryDebugger": 0,
        "scrapy.extensions.closespider.CloseSpider": 0,
        "scrapy.extensions.feedexport.FeedExporter": 0,
        "scrapy.extensions.logstats.LogStats": 0,
        "scrapy.extensions.spiderstate.SpiderState": 0,
        "scrapy.extensions.throttle.AutoThrottle": 0,
    }

A dict containing the extensions available by default in Scrapy, and their
orders. This setting contains all stable built-in extensions. Keep in mind that
some of them need to be enabled through a setting.

For more information See the :ref:`extensions user guide  <topics-extensions>`
and the :ref:`list of available extensions <topics-extensions-ref>`.

.. setting:: FEED_TEMPDIR

FEED_TEMPDIR
------------

Default: ``None``

The Feed Temp dir allows you to set a custom folder to save crawler
temporary files before uploading with :ref:`FTP feed storage <feed-storage-ftp>` and
:ref:`Amazon S3 <topics-feed-storage-s3>`.

.. setting:: FEED_STORAGE_GCS_ACL

FEED_STORAGE_GCS_ACL
--------------------

Default: ``""``

The Access Control List (ACL) used when storing items to :ref:`Google Cloud Storage <topics-feed-storage-gcs>`.
For more information on how to set this value, please refer to the column *JSON API* in `Google Cloud documentation <https://docs.cloud.google.com/storage/docs/access-control/lists>`_.

.. setting:: FORCE_CRAWLER_PROCESS

FORCE_CRAWLER_PROCESS
---------------------

Default: ``False``

If ``False``, :ref:`Scrapy commands that need a CrawlerProcess
<topics-commands-crawlerprocess>`, when :setting:`TWISTED_REACTOR_ENABLED`
is set to ``True``, will decide between using
:class:`scrapy.crawler.AsyncCrawlerProcess` and
:class:`scrapy.crawler.CrawlerProcess` based on the value of the
:setting:`TWISTED_REACTOR` setting, but ignoring its value in :ref:`per-spider
settings <spider-settings>`.

If ``True``, these commands will always use
:class:`~scrapy.crawler.CrawlerProcess` when :setting:`TWISTED_REACTOR_ENABLED`
is set to ``True``.

When :setting:`TWISTED_REACTOR_ENABLED` is set to ``False``,
:class:`~scrapy.crawler.AsyncCrawlerProcess` will be used in all cases.

Set this to ``True`` if you want to set :setting:`TWISTED_REACTOR` to a
non-default value in :ref:`per-spider settings <spider-settings>`.

.. note:: This is a :ref:`pre-crawler setting <pre-crawler-settings>`.

.. setting:: FTP_PASSIVE_MODE

FTP_PASSIVE_MODE
----------------

Default: ``True``

Whether or not to use passive mode when initiating FTP transfers.

.. note::

    Handling of this setting needs to be implemented inside the :ref:`download
    handler <topics-download-handlers>`, so it's not guaranteed to be supported
    by all 3rd-party handlers.

.. reqmeta:: ftp_password
.. setting:: FTP_PASSWORD

FTP_PASSWORD
------------

Default: ``"guest"``

The password to use for FTP connections when there is no ``"ftp_password"``
in ``Request`` meta.

.. note::
    Paraphrasing `RFC 1635`_, although it is common to use either the password
    "guest" or one's e-mail address for anonymous FTP,
    some FTP servers explicitly ask for the user's e-mail address
    and will not allow login with the "guest" password.

.. _RFC 1635: https://datatracker.ietf.org/doc/html/rfc1635

.. note::

    Handling of this setting needs to be implemented inside the :ref:`download
    handler <topics-download-handlers>`, so it's not guaranteed to be supported
    by all 3rd-party handlers.

.. reqmeta:: ftp_user
.. setting:: FTP_USER

FTP_USER
--------

Default: ``"anonymous"``

The username to use for FTP connections when there is no ``"ftp_user"``
in ``Request`` meta.

.. note::

    Handling of this setting needs to be implemented inside the :ref:`download
    handler <topics-download-handlers>`, so it's not guaranteed to be supported
    by all 3rd-party handlers.

.. setting:: GCS_PROJECT_ID

GCS_PROJECT_ID
-----------------

Default: ``None``

The Project ID that will be used when storing data on `Google Cloud Storage`_.

.. setting:: ITEM_PIPELINES

ITEM_PIPELINES
--------------

Default: ``{}``

A dict containing the item pipelines to use, and their orders. Order values are
arbitrary, but it is customary to define them in the 0-1000 range. Lower orders
process before higher orders.

Example:

.. code-block:: python

   ITEM_PIPELINES = {
       "mybot.pipelines.validate.ValidateMyItem": 300,
       "mybot.pipelines.validate.StoreMyItem": 800,
   }

.. setting:: ITEM_PIPELINES_BASE

ITEM_PIPELINES_BASE
-------------------

Default: ``{}``

A dict containing the pipelines enabled by default in Scrapy. You should never
modify this setting in your project, modify :setting:`ITEM_PIPELINES` instead.


.. setting:: JOBDIR

JOBDIR
------

Default: ``None``

A string indicating the directory for storing the state of a crawl when
:ref:`pausing and resuming crawls <topics-jobs>`.


.. setting:: LOG_ENABLED

LOG_ENABLED
-----------

Default: ``True``

Whether to enable logging.

.. note:: This is a :ref:`logging setting <logging-settings>`.

.. setting:: LOG_ENCODING

LOG_ENCODING
------------

Default: ``'utf-8'``

The encoding to use for logging.

.. note:: This is a :ref:`logging setting <logging-settings>`.

.. setting:: LOG_FILE

LOG_FILE
--------

Default: ``None``

File name to use for logging output. If ``None``, standard error will be used.

.. note:: This is a :ref:`logging setting <logging-settings>`.

.. setting:: LOG_FILE_APPEND

LOG_FILE_APPEND
---------------

Default: ``True``

If ``False``, the log file specified with :setting:`LOG_FILE` will be
overwritten (discarding the output from previous runs, if any).

.. note:: This is a :ref:`logging setting <logging-settings>`.

.. setting:: LOG_FORMAT

LOG_FORMAT
----------

Default: ``'%(asctime)s [%(name)s] %(levelname)s: %(message)s'``

String for formatting log messages. Refer to the
:ref:`Python logging documentation <logrecord-attributes>` for the whole
list of available placeholders.

.. note:: This is a :ref:`logging setting <logging-settings>`.

.. setting:: LOG_DATEFORMAT

LOG_DATEFORMAT
--------------

Default: ``'%Y-%m-%d %H:%M:%S'``

String for formatting date/time, expansion of the ``%(asctime)s`` placeholder
in :setting:`LOG_FORMAT`. Refer to the
:ref:`Python datetime documentation <strftime-strptime-behavior>` for the
whole list of available directives.

.. note:: This is a :ref:`logging setting <logging-settings>`.

.. setting:: LOG_FORMATTER

LOG_FORMATTER
-------------

Default: :class:`scrapy.logformatter.LogFormatter`

The class to use for :ref:`formatting log messages <custom-log-formats>` for different actions.

.. setting:: LOG_LEVEL

LOG_LEVEL
---------

Default: ``'DEBUG'``

Minimum level to log. Available levels are: CRITICAL, ERROR, WARNING,
INFO, DEBUG. For more info see :ref:`topics-logging`.

.. note:: This is a :ref:`logging setting <logging-settings>`.

.. setting:: LOG_STDOUT

LOG_STDOUT
----------

Default: ``False``

If ``True``, all standard output (and error) of your process will be redirected
to the log. For example if you ``print('hello')`` it will appear in the Scrapy
log.

.. note:: This is a :ref:`logging setting <logging-settings>`.

.. setting:: LOG_SHORT_NAMES

LOG_SHORT_NAMES
---------------

Default: ``False``

If ``True``, the logs will just contain the root path. If it is set to ``False``
then it displays the component responsible for the log output

.. note:: This is a :ref:`logging setting <logging-settings>`.

.. setting:: LOG_VERSIONS

LOG_VERSIONS
------------

Default: ``["lxml", "libxml2", "cssselect", "parsel", "w3lib", "Twisted", "Python", "pyOpenSSL", "cryptography", "Platform"]``

Logs the installed versions of the specified items.

An item can be any installed Python package.

The following special items are also supported:

-   ``libxml2``

-   ``Platform`` (:func:`platform.platform`)

-   ``Python``

-   ``pyOpenSSL``

.. setting:: LOGSTATS_INTERVAL

LOGSTATS_INTERVAL
-----------------

Default: ``60.0``

The interval (in seconds) between each logging printout of the stats
by :class:`~scrapy.extensions.logstats.LogStats`.

.. setting:: MEMDEBUG_ENABLED

MEMDEBUG_ENABLED
----------------

Default: ``False``

Whether to enable memory debugging.

.. setting:: MEMUSAGE_ENABLED

MEMUSAGE_ENABLED
----------------

Default: ``True``

Scope: ``scrapy.extensions.memusage.MemoryUsage``

Whether to enable the memory usage extension. This extension keeps track of
a peak memory used by the process (it writes it to stats). It can also
optionally shutdown the Scrapy process when it exceeds a memory limit
(see :setting:`MEMUSAGE_LIMIT_MB`).

See :ref:`topics-extensions-ref-memusage`.

.. setting:: MEMUSAGE_LIMIT_MB

MEMUSAGE_LIMIT_MB
-----------------

Default: ``0``

Scope: ``scrapy.extensions.memusage.MemoryUsage``

The maximum amount of memory to allow (in megabytes) before shutting down
Scrapy (if :setting:`MEMUSAGE_ENABLED` is ``True``). If zero, no check will be
performed.

See :ref:`topics-extensions-ref-memusage`.

.. setting:: MEMUSAGE_CHECK_INTERVAL_SECONDS

MEMUSAGE_CHECK_INTERVAL_SECONDS
-------------------------------

Default: ``60.0``

Scope: ``scrapy.extensions.memusage.MemoryUsage``

The :ref:`Memory usage extension <topics-extensions-ref-memusage>`
checks the current memory usage, versus the limits set by
:setting:`MEMUSAGE_LIMIT_MB` and :setting:`MEMUSAGE_WARNING_MB`,
at fixed time intervals.

This sets the length of these intervals, in seconds.

See :ref:`topics-extensions-ref-memusage`.

.. setting:: MEMUSAGE_WARNING_MB

MEMUSAGE_WARNING_MB
-------------------

Default: ``0``

Scope: ``scrapy.extensions.memusage.MemoryUsage``

The maximum amount of memory to allow (in megabytes) before sending a
:signal:`memusage_warning_reached` signal (if :setting:`MEMUSAGE_ENABLED` is
``True``). If zero, no signal will be sent.

See :ref:`topics-extensions-ref-memusage`.

.. setting:: NEWSPIDER_MODULE

NEWSPIDER_MODULE
----------------

Default: ``"<project name>.spiders"`` (:ref:`fallback <default-settings>`: ``""``)

Module where to create new spiders using the :command:`genspider` command.

Example:

.. code-block:: python

    NEWSPIDER_MODULE = "mybot.spiders_dev"

.. setting:: RANDOMIZE_DOWNLOAD_DELAY

RANDOMIZE_DOWNLOAD_DELAY
------------------------

Default: ``True``

If enabled, Scrapy will wait a random amount of time (between 0.5 * :setting:`DOWNLOAD_DELAY` and 1.5 * :setting:`DOWNLOAD_DELAY`) while fetching requests from the same
website.

This randomization decreases the chance of the crawler being detected (and
subsequently blocked) by sites which analyze requests looking for statistically
significant similarities in the time between their requests.

The randomization policy is the same used by `wget`_ ``--random-wait`` option.

If :setting:`DOWNLOAD_DELAY` is zero this option has no effect.

It is possible to change this setting per domain by using
:setting:`DOWNLOAD_SLOTS`.

.. _wget: https://www.gnu.org/software/wget/manual/wget.html

.. setting:: REACTOR_THREADPOOL_MAXSIZE

REACTOR_THREADPOOL_MAXSIZE
--------------------------

Default: ``10``

The maximum limit for Twisted Reactor thread pool size. This is common
multi-purpose thread pool used by various Scrapy components. Threaded
DNS Resolver, BlockingFeedStorage, S3FilesStore just to name a few. Increase
this value if you're experiencing problems with insufficient blocking IO.

.. note:: This is a :ref:`reactor setting <reactor-settings>`.

.. setting:: REDIRECT_PRIORITY_ADJUST

REDIRECT_PRIORITY_ADJUST
------------------------

Default: ``+2``

Scope: ``scrapy.downloadermiddlewares.redirect.RedirectMiddleware``

Adjust redirect request priority relative to original request:

- **a positive priority adjust (default) means higher priority.**
- a negative priority adjust means lower priority.

.. setting:: ROBOTSTXT_OBEY

ROBOTSTXT_OBEY
--------------

Default: ``True`` (:ref:`fallback <default-settings>`: ``False``)

If enabled, Scrapy will respect robots.txt policies. For more information see
:ref:`topics-dlmw-robots`.

.. note::

    While the default value is ``False`` for historical reasons,
    this option is enabled by default in settings.py file generated
    by ``scrapy startproject`` command.

.. setting:: ROBOTSTXT_PARSER

ROBOTSTXT_PARSER
----------------

Default: ``'scrapy.robotstxt.ProtegoRobotParser'``

The parser backend to use for parsing ``robots.txt`` files. For more information see
:ref:`topics-dlmw-robots`.

.. setting:: ROBOTSTXT_USER_AGENT

ROBOTSTXT_USER_AGENT
--------------------

Default: ``None``

The user agent string to use for matching in the robots.txt file. If ``None``,
the User-Agent header you are sending with the request or the
:setting:`USER_AGENT` setting (in that order) will be used for determining
the user agent to use in the robots.txt file.

.. setting:: SCHEDULER

SCHEDULER
---------

Default: :class:`~scrapy.core.scheduler.Scheduler`

The scheduler class to be used for crawling. See :ref:`topics-scheduler` for
details.

.. setting:: SCHEDULER_DEBUG

SCHEDULER_DEBUG
---------------

Default: ``False``

Setting to ``True`` will log debug information about the requests scheduler.
This currently logs (only once) if the requests cannot be serialized to disk.
The :stat:`scheduler/unserializable` stat tracks the number of times this
happens.

Example entry in logs::

    1956-01-31 00:00:00+0800 [scrapy.core.scheduler] ERROR: Unable to serialize request:
    <GET http://example.com> - reason: cannot serialize <Request at 0x9a7c7ec>
    (type Request)> - no more unserializable requests will be logged
    (see 'scheduler/unserializable' stats counter)


.. setting:: SCHEDULER_DISK_QUEUE

SCHEDULER_DISK_QUEUE
--------------------

Default: ``'scrapy.squeues.PickleLifoDiskQueue'``

Type of disk queue that will be used by the scheduler. Other available types
are ``scrapy.squeues.PickleFifoDiskQueue``,
``scrapy.squeues.MarshalFifoDiskQueue``,
``scrapy.squeues.MarshalLifoDiskQueue``.


.. setting:: SCHEDULER_MEMORY_QUEUE

SCHEDULER_MEMORY_QUEUE
----------------------

Default: ``'scrapy.squeues.LifoMemoryQueue'``

Type of in-memory queue used by the scheduler. Other available type is:
``scrapy.squeues.FifoMemoryQueue``.


.. setting:: SCHEDULER_PRIORITY_QUEUE
.. _broad-crawls-scheduler-priority-queue:

SCHEDULER_PRIORITY_QUEUE
------------------------

Default: :class:`~scrapy.pqueues.DownloaderAwarePriorityQueue`

Type of priority queue used by the scheduler.

Another available type is :class:`~scrapy.pqueues.ScrapyPriorityQueue`.

:class:`~scrapy.pqueues.DownloaderAwarePriorityQueue` works better than
:class:`~scrapy.pqueues.ScrapyPriorityQueue` when you crawl many different
domains in parallel.


.. setting:: SCHEDULER_START_DISK_QUEUE

SCHEDULER_START_DISK_QUEUE
--------------------------

Default: ``'scrapy.squeues.PickleFifoDiskQueue'``

Type of disk queue (see :setting:`JOBDIR`) that the :ref:`scheduler
<topics-scheduler>` uses for :ref:`start requests <start-requests>`.

For available choices, see :setting:`SCHEDULER_DISK_QUEUE`.

.. queue-common-starts

Use ``None`` or ``""`` to disable these separate queues entirely, and instead
have start requests share the same queues as other requests.

.. note::

    Disabling separate start request queues makes :ref:`start request order
    <start-request-order>` unintuitive: start requests will be sent in order
    only until :setting:`CONCURRENT_REQUESTS` is reached, then remaining start
    requests will be sent in reverse order.

.. queue-common-ends


.. setting:: SCHEDULER_START_MEMORY_QUEUE

SCHEDULER_START_MEMORY_QUEUE
----------------------------

Default: ``'scrapy.squeues.FifoMemoryQueue'``

Type of in-memory queue that the :ref:`scheduler <topics-scheduler>` uses for
:ref:`start requests <start-requests>`.

For available choices, see :setting:`SCHEDULER_MEMORY_QUEUE`.

.. include:: settings.rst
    :start-after: queue-common-starts
    :end-before: queue-common-ends


.. setting:: SCRAPER_SLOT_MAX_ACTIVE_SIZE

SCRAPER_SLOT_MAX_ACTIVE_SIZE
----------------------------

Default: ``5_000_000``

Soft limit (in bytes) for response data being processed.

While the sum of the sizes of all responses being processed is above this value,
Scrapy does not process new requests.

.. setting:: SPIDER_CONTRACTS

SPIDER_CONTRACTS
----------------

Default: ``{}``

A dict containing the spider contracts enabled in your project, used for
testing spiders. For more info see :ref:`topics-contracts`.

.. setting:: SPIDER_CONTRACTS_BASE

SPIDER_CONTRACTS_BASE
---------------------

Default:

.. code-block:: python

    {
        "scrapy.contracts.default.UrlContract": 1,
        "scrapy.contracts.default.CallbackKeywordArgumentsContract": 1,
        "scrapy.contracts.default.MetadataContract": 1,
        "scrapy.contracts.default.ReturnsContract": 2,
        "scrapy.contracts.default.ScrapesContract": 3,
    }

A dict containing the Scrapy contracts enabled by default in Scrapy. You should
never modify this setting in your project, modify :setting:`SPIDER_CONTRACTS`
instead. For more info see :ref:`topics-contracts`.

You can disable any of these contracts by assigning ``None`` to their class
path in :setting:`SPIDER_CONTRACTS`. E.g., to disable the built-in
``ScrapesContract``, place this in your ``settings.py``:

.. code-block:: python

    SPIDER_CONTRACTS = {
        "scrapy.contracts.default.ScrapesContract": None,
    }

.. setting:: SPIDER_LOADER_CLASS

SPIDER_LOADER_CLASS
-------------------

Default: ``'scrapy.spiderloader.SpiderLoader'``

The class that will be used for loading spiders, which must implement the
:ref:`topics-api-spiderloader`.

.. note:: This is a :ref:`pre-crawler setting <pre-crawler-settings>`.

.. setting:: SPIDER_LOADER_WARN_ONLY

SPIDER_LOADER_WARN_ONLY
-----------------------

Default: ``False``

By default, when Scrapy tries to import spider classes from :setting:`SPIDER_MODULES`,
it will fail loudly if there is any ``ImportError`` or ``SyntaxError`` exception.
But you can choose to silence this exception and turn it into a simple
warning by setting ``SPIDER_LOADER_WARN_ONLY = True``.

.. note:: This is a :ref:`pre-crawler setting <pre-crawler-settings>`.

.. setting:: SPIDER_MIDDLEWARES

SPIDER_MIDDLEWARES
------------------

Default: ``{}``

A dict containing the spider middlewares enabled in your project, and their
orders. For more info see :ref:`topics-spider-middleware-setting`.

.. setting:: SPIDER_MIDDLEWARES_BASE

SPIDER_MIDDLEWARES_BASE
-----------------------

Default:

.. code-block:: python

    {
        "scrapy.spidermiddlewares.start.StartSpiderMiddleware": 25,
        "scrapy.spidermiddlewares.httperror.HttpErrorMiddleware": 50,
        "scrapy.spidermiddlewares.referer.RefererMiddleware": 700,
        "scrapy.spidermiddlewares.urllength.UrlLengthMiddleware": 800,
        "scrapy.spidermiddlewares.depth.DepthMiddleware": 900,
    }

A dict containing the spider middlewares enabled by default in Scrapy, and
their orders. Low orders are closer to the engine, high orders are closer to
the spider. For more info see :ref:`topics-spider-middleware-setting`.

.. setting:: SPIDER_MODULES

SPIDER_MODULES
--------------

Default: ``["<project name>.spiders"]`` (:ref:`fallback <default-settings>`: ``[]``)

A list of modules where Scrapy will look for spiders.

Example:

.. code-block:: python

    SPIDER_MODULES = ["mybot.spiders_prod", "mybot.spiders_dev"]

.. note:: This is a :ref:`pre-crawler setting <pre-crawler-settings>`.

.. setting:: STATS_CLASS

STATS_CLASS
-----------

Default: ``'scrapy.statscollectors.MemoryStatsCollector'``

The class to use for collecting stats, who must implement the
:ref:`topics-api-stats`.

.. setting:: STATS_DUMP

STATS_DUMP
----------

Default: ``True``

Dump the :ref:`Scrapy stats <topics-stats>` (to the Scrapy log) once the spider
finishes.

For more info see: :ref:`topics-stats`.

.. setting:: TELNETCONSOLE_ENABLED

TELNETCONSOLE_ENABLED
---------------------

Default: ``True`` (``False`` when :setting:`TWISTED_REACTOR_ENABLED` is ``False``)

A boolean which specifies if the :ref:`telnet console <topics-telnetconsole>`
will be enabled (provided its extension is also enabled).

.. seealso:: :ref:`security-telnet`

.. setting:: TEMPLATES_DIR

TEMPLATES_DIR
-------------

Default: ``templates`` dir inside scrapy module

The directory where to look for templates when creating new projects with
:command:`startproject` command and new spiders with :command:`genspider`
command.

The project name must not conflict with the name of custom files or directories
in the ``project`` subdirectory.

.. setting:: TWISTED_DNS_RESOLVER

TWISTED_DNS_RESOLVER
--------------------

Default: ``'scrapy.resolver.CachingThreadedResolver'``

The class to be used by Twisted to resolve DNS names. The default
``scrapy.resolver.CachingThreadedResolver`` supports specifying a timeout for
DNS requests via the :setting:`DNS_TIMEOUT` setting, but works only with IPv4
addresses. Scrapy provides an alternative resolver,
``scrapy.resolver.CachingHostnameResolver``, which supports IPv4/IPv6 addresses but does not
take the :setting:`DNS_TIMEOUT` setting into account.

.. note::
    This setting has no effect when :setting:`TWISTED_REACTOR_ENABLED` is ``False``.

.. note:: This is a :ref:`reactor setting <reactor-settings>`.

.. setting:: TWISTED_REACTOR_ENABLED

TWISTED_REACTOR_ENABLED
-----------------------

Default: ``True``

Whether to install and use the Twisted reactor.

If this is set to ``True``, Scrapy will use the Twisted reactor and will
install one according to the :setting:`TWISTED_REACTOR` setting value when
appropriate (e.g. when running via :ref:`the command-line tool
<topics-commands>`). This is the traditional mode of using Scrapy.

If this is set to ``False``, Scrapy will use the asyncio event loop directly
and will not attempt to install or use a reactor. Features that require a
reactor won't be available, but Twisted APIs that don't require a reactor,
including :class:`~twisted.internet.defer.Deferred` and
:class:`~twisted.python.failure.Failure`, will still be available. On the other
hand, limitations related to Twisted reactors (such as not being able to start
a reactor in the same process where a reactor was previously started and
stopped) will not apply. This mode is currently experimental and may not be
suitable for production use. It may also not be supported by 3rd-party code.
See :ref:`asyncio-without-reactor` for more information about this mode.

.. note:: This is a :ref:`pre-crawler setting <pre-crawler-settings>`.

.. versionadded:: 2.15.0

.. setting:: TWISTED_REACTOR

TWISTED_REACTOR
---------------

Default: ``"twisted.internet.asyncioreactor.AsyncioSelectorReactor"``

Import path of a given :mod:`~twisted.internet.reactor`.

.. note::
    This setting has no effect when :setting:`TWISTED_REACTOR_ENABLED` is ``False``.

Scrapy will install this reactor if no other reactor is installed yet, such as
when the ``scrapy`` CLI program is invoked or when using the
:class:`~scrapy.crawler.AsyncCrawlerProcess` class or the
:class:`~scrapy.crawler.CrawlerProcess` class.

If you are using the :class:`~scrapy.crawler.AsyncCrawlerRunner` class or the
:class:`~scrapy.crawler.CrawlerRunner` class, you also
need to install the correct reactor manually. You can do that using
:func:`~scrapy.utils.reactor.install_reactor`:

.. autofunction:: scrapy.utils.reactor.install_reactor

If a reactor is already installed,
:func:`~scrapy.utils.reactor.install_reactor` has no effect.

:class:`~scrapy.crawler.AsyncCrawlerRunner` and other similar classes raise an
exception if the installed reactor does not match the
:setting:`TWISTED_REACTOR` setting; therefore, having top-level
:mod:`~twisted.internet.reactor` imports in project files and imported
third-party libraries will make Scrapy raise an exception when it checks which
reactor is installed.

In order to use the reactor installed by Scrapy:

.. skip: next
.. code-block:: python

    import scrapy
    from twisted.internet import reactor


    class QuotesSpider(scrapy.Spider):
        name = "quotes"

        def __init__(self, *args, **kwargs):
            self.timeout = int(kwargs.pop("timeout", "60"))
            super().__init__(*args, **kwargs)

        async def start(self):
            reactor.callLater(self.timeout, self.stop)

            urls = ["https://quotes.toscrape.com/page/1"]
            for url in urls:
                yield scrapy.Request(url=url, callback=self.parse)

        def parse(self, response):
            for quote in response.css("div.quote"):
                yield {"text": quote.css("span.text::text").get()}

        def stop(self):
            self.crawler.engine.close_spider(self, "timeout")


which raises an exception, becomes:

.. code-block:: python

    import scrapy


    class QuotesSpider(scrapy.Spider):
        name = "quotes"

        def __init__(self, *args, **kwargs):
            self.timeout = int(kwargs.pop("timeout", "60"))
            super().__init__(*args, **kwargs)

        async def start(self):
            from twisted.internet import reactor

            reactor.callLater(self.timeout, self.stop)

            urls = ["https://quotes.toscrape.com/page/1"]
            for url in urls:
                yield scrapy.Request(url=url, callback=self.parse)

        def parse(self, response):
            for quote in response.css("div.quote"):
                yield {"text": quote.css("span.text::text").get()}

        def stop(self):
            self.crawler.engine.close_spider(self, "timeout")


If this setting is set ``None``, Scrapy will use the existing reactor if one is
already installed, or install the default reactor defined by Twisted for the
current platform.

.. versionchanged:: 2.13
   The default value was changed from ``None`` to
   ``"twisted.internet.asyncioreactor.AsyncioSelectorReactor"``.

For additional information, see :doc:`core/howto/choosing-reactor`.

.. note:: This is a :ref:`reactor setting <reactor-settings>`.

.. setting:: URLLENGTH_LIMIT

URLLENGTH_LIMIT
---------------

Default: ``2083``

Scope: ``scrapy.spidermiddlewares.urllength``

The maximum URL length to allow for crawled URLs.

This setting can act as a stopping condition in case of URLs of ever-increasing
length, which may be caused for example by a programming error either in the
target server or in your code. See also :setting:`REDIRECT_MAX_TIMES` and
:setting:`DEPTH_LIMIT`.

Use ``0`` to allow URLs of any length.

The default value is copied from the `Microsoft Internet Explorer maximum URL
length`_, even though this setting exists for different reasons.

.. _Microsoft Internet Explorer maximum URL length: https://web.archive.org/web/20250206050143/https://support.microsoft.com/en-us/topic/maximum-url-length-is-2-083-characters-in-internet-explorer-174e7c8a-6666-f4e0-6fd6-908b53c12246

.. setting:: USER_AGENT

USER_AGENT
----------

Default: ``"Scrapy/VERSION (+https://scrapy.org)"``

The default User-Agent to use when crawling, unless overridden. This user agent is
also used by :class:`~scrapy.downloadermiddlewares.robotstxt.RobotsTxtMiddleware`
if :setting:`ROBOTSTXT_USER_AGENT` setting is ``None`` and
there is no overriding User-Agent header specified for the request.

Set it to a value that identifies you, including a URL or an email address
where website owners can reach you, e.g. ``"MyProject
(+https://example.com/bot)"``, so that they can ask you to adjust your crawler
rather than block it.

.. setting:: WARN_ON_GENERATOR_RETURN_VALUE

WARN_ON_GENERATOR_RETURN_VALUE
------------------------------

Default: ``True``

When enabled, Scrapy will warn if generator-based callback methods (like
``parse``) contain return statements with non-``None`` values. This helps detect
potential mistakes in spider development.

Disable this setting to prevent syntax errors that may occur when dynamically
modifying generator function source code during runtime, skip AST parsing of
callback functions, or improve performance in auto-reloading development
environments.

Settings documented elsewhere:
------------------------------

The following settings are documented elsewhere, please check each specific
case to see how to enable and use them.

.. settingslist::

.. _Amazon web services: https://aws.amazon.com/
.. _Google Cloud Storage: https://cloud.google.com/storage/