kraken

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// Copyright (c) 2016-2019 Uber Technologies, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//     http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package main
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import (
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	"encoding/json"
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	"net/http"
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	"os"
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	"time"
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	"github.com/docker/distribution/notifications"
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	"github.com/uber/kraken/utils/log"
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)
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const (
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	baseManifestQuery = "http://%s/v2/%s/manifests/%s"
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	baseLayerQuery    = "http://%s/v2/%s/blobs/%s"
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	transferTimeout   = 120 * time.Second
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	localSource       = "localhost:5051"
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	tempDir           = "/tmp/kraken/tmp/puller/"
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)
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// HealthHandler tells haproxy we'fre still alive
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func HealthHandler(w http.ResponseWriter, request *http.Request) {
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	w.Header().Set("Content-Type", "text/plain")
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	w.Write([]byte("OK"))
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}
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// NotificationHandler receives docker push notification
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type NotificationHandler struct {
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	queue     chan uint8
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	useDocker bool
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}
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// NewNotificationHandler creates a new Notifaction
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func NewNotificationHandler(maxChanSize int, useDocker bool) (*NotificationHandler, error) {
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	if err := os.MkdirAll(tempDir, 0775); err != nil {
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		return nil, err
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	}
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	return &NotificationHandler{
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		queue:     make(chan byte, maxChanSize),
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		useDocker: useDocker,
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	}, nil
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}
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// Handler handles messages defined in http://godoc.org/github.com/docker/distribution/notifications.
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func (n *NotificationHandler) Handler(w http.ResponseWriter, r *http.Request) {
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	log.Debugf("notification received")
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	decoder := json.NewDecoder(r.Body)
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	var envelope notifications.Envelope
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	if err := decoder.Decode(&envelope); err != nil {
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		log.With("err", err).Error("cannot decode envelope")
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		return
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	}
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	for _, event := range envelope.Events {
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		if event.Action == notifications.EventActionPush {
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			url := event.Target.URL
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			repo := event.Target.Repository
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			tag := event.Target.Tag
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			digest := guessDigest(url, repo)
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			if len(digest) == 0 {
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				log.Debugf("non tag push action: target.URL: '%s', target.Repository: '%s'", url, repo)
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			} else {
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				select {
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				case n.queue <- 'c':
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					time.Sleep(2 * time.Second)
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					go func() {
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						PullImage(localSource, repo, tag, n.useDocker)
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						<-n.queue
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					}()
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				default:
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					// drop if queue full
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					log.Infof("queue full. drop %s:%s", repo, tag)
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				}
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			}
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		}
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	}
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	w.Header().Set("Content-Type", "application/json")
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	resString := "OK"
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	w.Write([]byte(resString))
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}
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