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Add pg_static synthetic key to collect Postgres version.

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Similar to the node_exporter, this key is synthetic and used to create
a constant metric which records the version strings of PostgreSQL in its
labels.
This commit is contained in:
Will Rouesnel 2016-11-17 01:59:46 +11:00
parent 8c0f2ed166
commit f554139279
1 changed files with 41 additions and 2 deletions
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43
postgres_exporter.go
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@ -16,6 +16,7 @@ import (
_ "github.com/lib/pq"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/common/log"
"regexp"
)
var Version string = "0.0.1"
@ -45,8 +46,15 @@ const (
namespace = "pg"
// Subsystems.
exporter = "exporter"
// Metric label used for static string data thats handy to send to Prometheus
// e.g. version
staticLabelName = "static"
)
// Highest version of Postgres we have explicit behavior for. This is the
// assumed default if the version string does match any known versions.
const HighestSupportedVersion = "9.6"
// landingPage contains the HTML served at '/'.
// TODO: Make this nicer and more informative.
var landingPage = []byte(`<html>
@ -69,8 +77,25 @@ const (
DURATION ColumnUsage = iota // This column should be interpreted as a text duration (and converted to milliseconds)
)
// Which metric mapping should be acquired using "SHOW" queries
const SHOW_METRIC = "pg_runtime_variables"
// Special case matric mappings
const (
// Which metric mapping should be acquired using "SHOW" queries
SHOW_METRIC = "pg_runtime_variables"
)
// Regex used to get the "short-version" from the postgres version field.
var versionRegex = regexp.MustCompile(`^\w+ (\d+\.\d+)`)
// Parses the version of postgres into the short version string we can use to
// match behaviors.
func parseVersion(versionString string) string {
submatches := versionRegex.FindStringSubmatch(versionString)
if len(submatches) > 1 {
return submatches[1]
}
log.Debugln("Could not parse postgres version regex:", versionString)
return ""
}
// User-friendly representation of a prometheus descriptor map
type ColumnMapping struct {
@ -580,6 +605,20 @@ func (e *Exporter) scrape(ch chan<- prometheus.Metric) {
}
defer db.Close()
log.Debugln("Querying Postgres Version")
versionRow := db.QueryRow("SELECT version();")
var versionString string
err = versionRow.Scan(&versionString)
if err != nil {
log.Errorln("Error scanning version string:", err)
e.error.Set(1)
return
}
shortVersion := parseVersion(versionString)
// Output the version as a special metric
versionDesc := prometheus.NewDesc(fmt.Sprintf("%s_%s", namespace, staticLabelName), "Version string as reported by postgres", []string{"version", "short_version"}, nil)
ch <- prometheus.MustNewConstMetric(versionDesc, prometheus.UntypedValue, 1, versionString, shortVersion)
log.Debugln("Querying SHOW variables")
for _, mapping := range e.variableMap {
for columnName, columnMapping := range mapping.columnMappings {