RepoMirrors
/
postgres_exporter
mirror of https://github.com/prometheus-community/postgres_exporter
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
postgres_exporter/postgres_exporter.go

414 lines
15 KiB
Go
Raw Normal View History

Compiling version of the postgres_exporter. This is based on the mysqld_exporter, but drastically changes how metrics are discovered and enumerated since postgres already very closely follows the Prometheus format.
2015-08-24 17:27:14 +00:00
package main
import (
//"bytes"
"database/sql"
"flag"
"fmt"
"net/http"
"os"
//"regexp"
//"strconv"
//"strings"
"time"
Add explicit type conversion functions from sql to prometheus.
2015-08-27 18:26:52 +00:00
"math"
Compiling version of the postgres_exporter. This is based on the mysqld_exporter, but drastically changes how metrics are discovered and enumerated since postgres already very closely follows the Prometheus format.
2015-08-24 17:27:14 +00:00
_ "github.com/lib/pq"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/log"
)
var (
listenAddress = flag.String(
"web.listen-address", ":9113",
"Address to listen on for web interface and telemetry.",
)
metricPath = flag.String(
"web.telemetry-path", "/metrics",
"Path under which to expose metrics.",
)
)
// Metric name parts.
const (
// Namespace for all metrics.
namespace = "pg"
// Subsystems.
exporter = "exporter"
)
// landingPage contains the HTML served at '/'.
// TODO: Make this nicer and more informative.
var landingPage = []byte(`<html>
<head><title>Postgres exporter</title></head>
<body>
<h1>Postgres exporter</h1>
<p><a href='` + *metricPath + `'>Metrics</a></p>
</body>
</html>
`)
type ColumnUsage int
const (
DISCARD ColumnUsage = iota // Ignore this column
LABEL ColumnUsage = iota // Use this column as a label
COUNTER ColumnUsage = iota // Use this column as a counter
GAUGE ColumnUsage = iota // Use this column as a gauge
MAPPEDMETRIC ColumnUsage = iota // Use this column with the supplied mapping of text values
)
// User-friendly representation of a prometheus descriptor map
type ColumnMapping struct {
usage ColumnUsage
description string
mapping map[string]float64 // Optional column mapping for MAPPEDMETRIC
}
// Groups metric maps under a shared set of labels
type MetricMapNamespace struct {
labels []string // Label names for this namespace
columnMappings map[string]MetricMap // Column mappings in this namespace
}
// Stores the prometheus metric description which a given column will be mapped
// to by the collector
type MetricMap struct {
discard bool // Should metric be discarded during mapping?
vtype prometheus.ValueType // Prometheus valuetype
desc *prometheus.Desc // Prometheus descriptor
mapping map[string]float64 // If not nil, maps text values to float64s
}
// Metric descriptors for dynamically created metrics.
var metricMaps = map[string]map[string]ColumnMapping {
"pg_stat_bgwriter" : map[string]ColumnMapping {
"checkpoints_timed" : { COUNTER, "Number of scheduled checkpoints that have been performed", nil },
"checkpoints_req" : { COUNTER, "Number of requested checkpoints that have been performed", nil },
"checkpoint_write_time" : { COUNTER, "Total amount of time that has been spent in the portion of checkpoint processing where files are written to disk, in milliseconds", nil },
"checkpoint_sync_time" : { COUNTER, "Total amount of time that has been spent in the portion of checkpoint processing where files are synchronized to disk, in milliseconds", nil },
"buffers_checkpoint" : { COUNTER, "Number of buffers written during checkpoints", nil },
"buffers_clean" : { COUNTER, "Number of buffers written by the background writer", nil },
"maxwritten_clean" : { COUNTER, "Number of times the background writer stopped a cleaning scan because it had written too many buffers", nil },
"buffers_backend" : { COUNTER, "Number of buffers written directly by a backend", nil },
"buffers_backend_fsync" : { COUNTER, "Number of times a backend had to execute its own fsync call (normally the background writer handles those even when the backend does its own write)", nil },
"buffers_alloc" : { COUNTER, "Number of buffers allocated", nil },
"stats_reset" : { COUNTER, "Time at which these statistics were last reset", nil },
},
"pg_stat_database" : map[string]ColumnMapping {
Add explicit type conversion functions from sql to prometheus.
2015-08-27 18:26:52 +00:00
"datid" : { LABEL, "OID of a database", nil },
"datname" : { LABEL, "Name of this database", nil },
"numbackends" : { GAUGE, "Number of backends currently connected to this database. This is the only column in this view that returns a value reflecting current state; all other columns return the accumulated values since the last reset.", nil },
Compiling version of the postgres_exporter. This is based on the mysqld_exporter, but drastically changes how metrics are discovered and enumerated since postgres already very closely follows the Prometheus format.
2015-08-24 17:27:14 +00:00
"xact_commit" : { COUNTER, "Number of transactions in this database that have been committed", nil },
"xact_rollback" : { COUNTER, "Number of transactions in this database that have been rolled back", nil },
"blks_read" : { COUNTER, "Number of disk blocks read in this database", nil },
"blks_hit" : { COUNTER, "Number of times disk blocks were found already in the buffer cache, so that a read was not necessary (this only includes hits in the PostgreSQL buffer cache, not the operating system's file system cache)", nil },
"tup_returned" : { COUNTER, "Number of rows returned by queries in this database", nil },
"tup_fetched" : { COUNTER, "Number of rows fetched by queries in this database", nil },
"tup_inserted" : { COUNTER, "Number of rows inserted by queries in this database", nil },
"tup_updated" : { COUNTER, "Number of rows updated by queries in this database", nil },
"tup_deleted" : { COUNTER, "Number of rows deleted by queries in this database", nil },
"conflicts" : { COUNTER, "Number of queries canceled due to conflicts with recovery in this database. (Conflicts occur only on standby servers; see pg_stat_database_conflicts for details.)", nil },
"temp_files" : { COUNTER, "Number of temporary files created by queries in this database. All temporary files are counted, regardless of why the temporary file was created (e.g., sorting or hashing), and regardless of the log_temp_files setting.", nil },
"temp_bytes" : { COUNTER, "Total amount of data written to temporary files by queries in this database. All temporary files are counted, regardless of why the temporary file was created, and regardless of the log_temp_files setting.", nil },
"deadlocks" : { COUNTER, "Number of deadlocks detected in this database", nil },
"blk_read_time" : { COUNTER, "Time spent reading data file blocks by backends in this database, in milliseconds", nil },
"blk_write_time" : { COUNTER, "Time spent writing data file blocks by backends in this database, in milliseconds", nil },
"stats_reset" : { COUNTER, "Time at which these statistics were last reset", nil },
},
"pg_stat_database_conflicts" : map[string]ColumnMapping {
Add explicit type conversion functions from sql to prometheus.
2015-08-27 18:26:52 +00:00
"datid" : { LABEL, "OID of a database", nil },
"datname" : { LABEL, "Name of this database", nil },
Compiling version of the postgres_exporter. This is based on the mysqld_exporter, but drastically changes how metrics are discovered and enumerated since postgres already very closely follows the Prometheus format.
2015-08-24 17:27:14 +00:00
"confl_tablespace" : { COUNTER, "Number of queries in this database that have been canceled due to dropped tablespaces", nil },
"confl_lock" : { COUNTER, "Number of queries in this database that have been canceled due to lock timeouts", nil },
"confl_snapshot" : { COUNTER, "Number of queries in this database that have been canceled due to old snapshots", nil },
"confl_bufferpin" : { COUNTER, "Number of queries in this database that have been canceled due to pinned buffers", nil },
"confl_deadlock" : { COUNTER, "Number of queries in this database that have been canceled due to deadlocks", nil },
},
}
// Turn the MetricMap column mapping into a prometheus descriptor mapping.
func makeDescMap(metricMaps map[string]map[string]ColumnMapping) map[string]MetricMapNamespace {
var metricMap = make(map[string]MetricMapNamespace)
for namespace, mappings := range metricMaps {
thisMap := make(map[string]MetricMap)
// Get the constant labels
var constLabels []string
for columnName, columnMapping := range mappings {
if columnMapping.usage == LABEL {
constLabels = append(constLabels, columnName)
}
}
for columnName, columnMapping := range mappings {
switch columnMapping.usage {
case DISCARD, LABEL:
thisMap[columnName] = MetricMap{
discard : true,
}
case COUNTER:
thisMap[columnName] = MetricMap{
vtype : prometheus.CounterValue,
desc : prometheus.NewDesc(fmt.Sprintf("%s_%s", namespace, columnName), columnMapping.description, constLabels, nil),
}
case GAUGE:
thisMap[columnName] = MetricMap{
vtype : prometheus.GaugeValue,
desc : prometheus.NewDesc(fmt.Sprintf("%s_%s", namespace, columnName), columnMapping.description, constLabels, nil),
}
case MAPPEDMETRIC:
thisMap[columnName] = MetricMap{
vtype : prometheus.GaugeValue,
desc : prometheus.NewDesc(fmt.Sprintf("%s_%s", namespace, columnName), columnMapping.description, constLabels, nil),
mapping: columnMapping.mapping,
}
}
}
metricMap[namespace] = MetricMapNamespace{ constLabels, thisMap }
}
return metricMap
}
Add explicit type conversion functions from sql to prometheus.
2015-08-27 18:26:52 +00:00
// Convert database.sql types to float64s for Prometheus consumption. Null types are mapped to NaN. string and []byte
// types are mapped as NaN and !ok
func dbToFloat64(t interface{}) (float64, bool) {
switch v := t.(type) {
case int64:
return float64(v), true
case float64:
return v, true
case time.Time:
return float64(v.Unix()), true
case nil:
return math.NaN(), true
default:
return math.NaN(), false
}
}
// Convert database.sql to string for Prometheus labels. Null types are mapped to empty strings.
func dbToString(t interface{}) (string, bool) {
switch v := t.(type) {
case int64:
return fmt.Sprintf("%v", v), true
case float64:
return fmt.Sprintf("%v", v), true
case time.Time:
return fmt.Sprintf("%v", v.Unix()), true
case nil:
return "", true
case []byte:
// Try and convert to string
return string(v), true
case string:
return v, true
default:
return "", false
}
}
Compiling version of the postgres_exporter. This is based on the mysqld_exporter, but drastically changes how metrics are discovered and enumerated since postgres already very closely follows the Prometheus format.
2015-08-24 17:27:14 +00:00
// Exporter collects MySQL metrics. It implements prometheus.Collector.
type Exporter struct {
dsn string
duration, error prometheus.Gauge
totalScrapes prometheus.Counter
metricMap map[string]MetricMapNamespace
}
// NewExporter returns a new MySQL exporter for the provided DSN.
func NewExporter(dsn string) *Exporter {
return &Exporter{
dsn: dsn,
duration: prometheus.NewGauge(prometheus.GaugeOpts{
Namespace: namespace,
Subsystem: exporter,
Name: "last_scrape_duration_seconds",
Help: "Duration of the last scrape of metrics from PostgresSQL.",
}),
totalScrapes: prometheus.NewCounter(prometheus.CounterOpts{
Namespace: namespace,
Subsystem: exporter,
Name: "scrapes_total",
Help: "Total number of times PostgresSQL was scraped for metrics.",
}),
error: prometheus.NewGauge(prometheus.GaugeOpts{
Namespace: namespace,
Subsystem: exporter,
Name: "last_scrape_error",
Help: "Whether the last scrape of metrics from PostgreSQL resulted in an error (1 for error, 0 for success).",
}),
metricMap : makeDescMap(metricMaps),
}
}
// Describe implements prometheus.Collector.
func (e *Exporter) Describe(ch chan<- *prometheus.Desc) {
// We cannot know in advance what metrics the exporter will generate
// from Postgres. So we use the poor man's describe method: Run a collect
// and send the descriptors of all the collected metrics. The problem
// here is that we need to connect to the Postgres DB. If it is currently
// unavailable, the descriptors will be incomplete. Since this is a
// stand-alone exporter and not used as a library within other code
// implementing additional metrics, the worst that can happen is that we
// don't detect inconsistent metrics created by this exporter
// itself. Also, a change in the monitored Postgres instance may change the
// exported metrics during the runtime of the exporter.
metricCh := make(chan prometheus.Metric)
doneCh := make(chan struct{})
go func() {
for m := range metricCh {
ch <- m.Desc()
}
close(doneCh)
}()
e.Collect(metricCh)
close(metricCh)
<-doneCh
}
// Collect implements prometheus.Collector.
func (e *Exporter) Collect(ch chan<- prometheus.Metric) {
e.scrape(ch)
ch <- e.duration
ch <- e.totalScrapes
ch <- e.error
}
func newDesc(subsystem, name, help string) *prometheus.Desc {
return prometheus.NewDesc(
prometheus.BuildFQName(namespace, subsystem, name),
help, nil, nil,
)
}
func (e *Exporter) scrape(ch chan<- prometheus.Metric) {
defer func(begun time.Time) {
e.duration.Set(time.Since(begun).Seconds())
}(time.Now())
e.error.Set(0)
e.totalScrapes.Inc()
db, err := sql.Open("postgres", e.dsn)
if err != nil {
log.Println("Error opening connection to database:", err)
e.error.Set(1)
return
}
defer db.Close()
for namespace, mapping := range e.metricMap {
Add explicit type conversion functions from sql to prometheus.
2015-08-27 18:26:52 +00:00
log.Debugln("Querying namespace: ", namespace)
Compiling version of the postgres_exporter. This is based on the mysqld_exporter, but drastically changes how metrics are discovered and enumerated since postgres already very closely follows the Prometheus format.
2015-08-24 17:27:14 +00:00
func () { // Don't fail on a bad scrape of one metric
rows, err := db.Query(fmt.Sprintf("SELECT * FROM %s;", namespace))
if err != nil {
log.Println("Error running query on database: ", namespace, err)
e.error.Set(1)
return
}
defer rows.Close()
var columnNames []string
columnNames, err = rows.Columns()
if err != nil {
log.Println("Error retrieving column list for: ", namespace, err)
e.error.Set(1)
return
}
// Make a lookup map for the column indices
var columnIdx = make(map[string]int, len(columnNames))
for i, n := range columnNames {
columnIdx[n] = i
}
Add explicit type conversion functions from sql to prometheus.
2015-08-27 18:26:52 +00:00
var columnData = make([]interface{}, len(columnNames))
Compiling version of the postgres_exporter. This is based on the mysqld_exporter, but drastically changes how metrics are discovered and enumerated since postgres already very closely follows the Prometheus format.
2015-08-24 17:27:14 +00:00
var scanArgs = make([]interface{}, len(columnNames))
for i := range columnData {
scanArgs[i] = &columnData[i]
}
for rows.Next() {
err = rows.Scan(scanArgs...)
if err != nil {
log.Println("Error retrieving rows:", namespace, err)
e.error.Set(1)
return
}
// Get the label values for this row
var labels = make([]string, len(mapping.labels))
for i, n := range labels {
Add explicit type conversion functions from sql to prometheus.
2015-08-27 18:26:52 +00:00
labels[i], _ = dbToString(columnData[columnIdx[n]])
Compiling version of the postgres_exporter. This is based on the mysqld_exporter, but drastically changes how metrics are discovered and enumerated since postgres already very closely follows the Prometheus format.
2015-08-24 17:27:14 +00:00
}
// Loop over column names, and match to scan data. Unknown columns
// will be filled with an untyped metric number *if* they can be
// converted to float64s. NULLs are allowed and treated as NaN.
for idx, columnName := range columnNames {
if metricMapping, ok := mapping.columnMappings[columnName]; ok {
// Is this a metricy metric?
if metricMapping.discard {
continue
}
Add explicit type conversion functions from sql to prometheus.
2015-08-27 18:26:52 +00:00
value, ok := dbToFloat64(columnData[idx])
if ! ok {
Compiling version of the postgres_exporter. This is based on the mysqld_exporter, but drastically changes how metrics are discovered and enumerated since postgres already very closely follows the Prometheus format.
2015-08-24 17:27:14 +00:00
e.error.Set(1)
Add explicit type conversion functions from sql to prometheus.
2015-08-27 18:26:52 +00:00
log.Errorln("Unexpected error parsing column: ", namespace, columnName, columnData[idx])
Compiling version of the postgres_exporter. This is based on the mysqld_exporter, but drastically changes how metrics are discovered and enumerated since postgres already very closely follows the Prometheus format.
2015-08-24 17:27:14 +00:00
continue
}
// Generate the metric
ch <- prometheus.MustNewConstMetric(metricMapping.desc, metricMapping.vtype, value, labels...)
} else {
// Unknown metric. Report as untyped if scan to float64 works, else note an error too.
desc := prometheus.NewDesc(fmt.Sprintf("%s_%s", namespace, columnName), fmt.Sprintf("Unknown metric from %s", namespace), nil, nil)
// Its not an error to fail here, since the values are
// unexpected anyway.
Add explicit type conversion functions from sql to prometheus.
2015-08-27 18:26:52 +00:00
value, ok := dbToFloat64(columnData[idx])
if ! ok {
log.Warnln("Unparseable column type - discarding: ", namespace, columnName, err)
continue
Compiling version of the postgres_exporter. This is based on the mysqld_exporter, but drastically changes how metrics are discovered and enumerated since postgres already very closely follows the Prometheus format.
2015-08-24 17:27:14 +00:00
}
ch <- prometheus.MustNewConstMetric(desc, prometheus.UntypedValue, value, labels...)
}
}
}
}()
}
}
func main() {
flag.Parse()
dsn := os.Getenv("DATA_SOURCE_NAME")
if len(dsn) == 0 {
log.Fatal("couldn't find environment variable DATA_SOURCE_NAME")
}
exporter := NewExporter(dsn)
prometheus.MustRegister(exporter)
http.Handle(*metricPath, prometheus.Handler())
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
w.Write(landingPage)
})
log.Infof("Starting Server: %s", *listenAddress)
log.Fatal(http.ListenAndServe(*listenAddress, nil))
}