124 lines
3.2 KiB
Go
124 lines
3.2 KiB
Go
// Copyright 2022 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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"github.com/go-kit/log"
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"github.com/prometheus/client_golang/prometheus"
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)
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const databaseSubsystem = "database"
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func init() {
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registerCollector(databaseSubsystem, defaultEnabled, NewPGDatabaseCollector)
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}
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type PGDatabaseCollector struct {
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log log.Logger
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excludedDatabases []string
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}
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func NewPGDatabaseCollector(config collectorConfig) (Collector, error) {
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exclude := config.excludeDatabases
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if exclude == nil {
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exclude = []string{}
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}
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return &PGDatabaseCollector{
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log: config.logger,
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excludedDatabases: exclude,
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}, nil
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}
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var (
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pgDatabaseSizeDesc = prometheus.NewDesc(
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prometheus.BuildFQName(
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namespace,
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databaseSubsystem,
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"size_bytes",
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),
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"Disk space used by the database",
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[]string{"datname"}, nil,
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)
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pgDatabaseQuery = "SELECT pg_database.datname FROM pg_database;"
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pgDatabaseSizeQuery = "SELECT pg_database_size($1)"
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)
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// Update implements Collector and exposes database size.
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// It is called by the Prometheus registry when collecting metrics.
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// The list of databases is retrieved from pg_database and filtered
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// by the excludeDatabase config parameter. The tradeoff here is that
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// we have to query the list of databases and then query the size of
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// each database individually. This is because we can't filter the
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// list of databases in the query because the list of excluded
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// databases is dynamic.
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func (c PGDatabaseCollector) 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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pgDatabaseQuery,
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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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var databases []string
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for rows.Next() {
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var datname string
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if err := rows.Scan(&datname); err != nil {
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return err
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}
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// Ignore excluded databases
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// Filtering is done here instead of in the query to avoid
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// a complicated NOT IN query with a variable number of parameters
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if sliceContains(c.excludedDatabases, datname) {
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continue
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}
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databases = append(databases, datname)
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}
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// Query the size of the databases
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for _, datname := range databases {
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var size int64
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err = db.QueryRowContext(ctx, pgDatabaseSizeQuery, datname).Scan(&size)
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if err != nil {
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return err
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}
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ch <- prometheus.MustNewConstMetric(
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pgDatabaseSizeDesc,
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prometheus.GaugeValue, float64(size), datname,
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)
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}
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if err := rows.Err(); err != nil {
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return err
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}
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return nil
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}
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func sliceContains(slice []string, s string) bool {
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for _, item := range slice {
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if item == s {
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return true
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}
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}
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return false
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}
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