From f554139279a9637179e1fb43fb485727b16c03de Mon Sep 17 00:00:00 2001
From: Will Rouesnel <w.rouesnel@gmail.com>
Date: Thu, 17 Nov 2016 01:59:46 +1100
Subject: [PATCH] Add pg_static synthetic key to collect Postgres version.
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.
---
postgres_exporter.go | 43 +++++++++++++++++++++++++++++++++++++++++--
1 file changed, 41 insertions(+), 2 deletions(-)
diff --git a/postgres_exporter.go b/postgres_exporter.go
index 6c66d06b..fe772eb8 100644
--- a/postgres_exporter.go
+++ b/postgres_exporter.go
@@ -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 {