pangolin_exporter

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// Copyright 2024 The Prometheus Authors
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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 collector
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import (
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	"context"
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	"database/sql"
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	"github.com/go-kit/log"
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	"github.com/prometheus/client_golang/prometheus"
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)
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const rolesSubsystem = "roles"
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func init() {
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	registerCollector(rolesSubsystem, defaultEnabled, NewPGRolesCollector)
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}
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type PGRolesCollector struct {
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	log log.Logger
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}
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func NewPGRolesCollector(config collectorConfig) (Collector, error) {
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	return &PGRolesCollector{
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		log: config.logger,
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	}, nil
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}
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var (
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	pgRolesConnectionLimitsDesc = prometheus.NewDesc(
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		prometheus.BuildFQName(
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			namespace,
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			rolesSubsystem,
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			"connection_limit",
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		),
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		"Connection limit set for the role",
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		[]string{"rolname"}, nil,
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	)
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	pgRolesConnectionLimitsQuery = "SELECT pg_roles.rolname, pg_roles.rolconnlimit FROM pg_roles"
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)
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// Update implements Collector and exposes roles connection limits.
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// It is called by the Prometheus registry when collecting metrics.
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func (c PGRolesCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
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	db := instance.getDB()
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	// Query the list of databases
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	rows, err := db.QueryContext(ctx,
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		pgRolesConnectionLimitsQuery,
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	)
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	if err != nil {
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		return err
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	}
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	defer rows.Close()
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	for rows.Next() {
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		var rolname sql.NullString
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		var connLimit sql.NullInt64
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		if err := rows.Scan(&rolname, &connLimit); err != nil {
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			return err
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		}
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		if !rolname.Valid {
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			continue
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		}
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		rolnameLabel := rolname.String
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		if !connLimit.Valid {
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			continue
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		}
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		connLimitMetric := float64(connLimit.Int64)
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		ch <- prometheus.MustNewConstMetric(
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			pgRolesConnectionLimitsDesc,
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			prometheus.GaugeValue, connLimitMetric, rolnameLabel,
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		)
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	}
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	return rows.Err()
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}
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