postgres_exporter/collector/replication_slots.go

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// Copyright 2023 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package collector
import (
"context"
"database/sql"
"github.com/go-kit/log"
"github.com/prometheus/client_golang/prometheus"
)
func init() {
registerCollector("replication_slot", defaultEnabled, NewPGReplicationSlotCollector)
}
type PGReplicationSlotCollector struct {
log log.Logger
}
func NewPGReplicationSlotCollector(logger log.Logger) (Collector, error) {
return &PGReplicationSlotCollector{log: logger}, nil
}
var pgReplicationSlot = map[string]*prometheus.Desc{
"current_wal_lsn": prometheus.NewDesc(
"pg_replication_slot_current_wal_lsn",
"current wal lsn value",
[]string{"slot_name"}, nil,
),
"confirmed_flush_lsn": prometheus.NewDesc(
"pg_replication_slot_confirmed_flush_lsn",
"last lsn confirmed flushed to the replication slot",
[]string{"slot_name"}, nil,
),
"is_active": prometheus.NewDesc(
"pg_replication_slot_is_active",
"last lsn confirmed flushed to the replication slot",
[]string{"slot_name"}, nil,
),
}
func (PGReplicationSlotCollector) Update(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric) error {
rows, err := db.QueryContext(ctx,
`SELECT
slot_name,
pg_current_wal_lsn() - '0/0' AS current_wal_lsn,
coalesce(confirmed_flush_lsn, '0/0') - '0/0',
active
FROM
pg_replication_slots;`)
if err != nil {
return err
}
defer rows.Close()
for rows.Next() {
var slot_name string
var wal_lsn int64
var flush_lsn int64
var is_active int
if err := rows.Scan(&slot_name, &wal_lsn, &flush_lsn, &is_active); err != nil {
return err
}
ch <- prometheus.MustNewConstMetric(
pgReplicationSlot["current_wal_lsn"],
prometheus.GaugeValue, float64(wal_lsn), slot_name,
)
if (is_active == 1) {
ch <- prometheus.MustNewConstMetric(
pgReplicationSlot["confirmed_flush_lsn"],
prometheus.GaugeValue, float64(flush_lsn), slot_name,
)
}
ch <- prometheus.MustNewConstMetric(
pgReplicationSlot["is_active"],
prometheus.GaugeValue, int(flush_lsn), slot_name,
)
}
if err := rows.Err(); err != nil {
return err
}
return nil
}