Postgresql database blacklist configuration option

CHANGELOG.md

@@ -18,6 +18,7 @@
 - [#1599](https://github.com/influxdata/telegraf/pull/1599): Add server hostname for each docker measurements.
 - [#1697](https://github.com/influxdata/telegraf/pull/1697): Add NATS output plugin.
 - [#1407](https://github.com/influxdata/telegraf/pull/1407): HTTP service listener input plugin.
+- [#1699](https://github.com/influxdata/telegraf/pull/1699): Add database blacklist option for Postgresql
 
 ### Bugfixes
 

plugins/inputs/postgresql/postgresql.go

@@ -17,6 +17,7 @@ import (
 type Postgresql struct {
 	Address          string
 	Databases        []string
+	IgnoredDatabases []string
 	OrderedColumns   []string
 	AllColumns       []string
 	sanitizedAddress string
@@ -40,8 +41,12 @@ var sampleConfig = `
   ##
   address = "host=localhost user=postgres sslmode=disable"
 
+  ## A  list of databases to explicitly ignore.  If not specified, metrics for all
+  ## databases are gathered.  Do NOT use with the 'databases' option.
+  # ignored_databases = ["postgres", "template0", "template1"]
+
   ## A list of databases to pull metrics about. If not specified, metrics for all
-  ## databases are gathered.
+  ## databases are gathered.  Do NOT use with the 'ignore_databases' option.
   # databases = ["app_production", "testing"]
 `
 
@@ -73,8 +78,11 @@ func (p *Postgresql) Gather(acc telegraf.Accumulator) error {
 
 	defer db.Close()
 
-	if len(p.Databases) == 0 {
+	if len(p.Databases) == 0 && len(p.IgnoredDatabases) == 0 {
 		query = `SELECT * FROM pg_stat_database`
+	} else if len(p.IgnoredDatabases) != 0 {
+		query = fmt.Sprintf(`SELECT * FROM pg_stat_database WHERE datname NOT IN ('%s')`,
+			strings.Join(p.IgnoredDatabases, "','"))
 	} else {
 		query = fmt.Sprintf(`SELECT * FROM pg_stat_database WHERE datname IN ('%s')`,
 			strings.Join(p.Databases, "','"))

plugins/inputs/postgresql/postgresql_test.go

@@ -150,3 +150,75 @@ func TestPostgresqlIgnoresUnwantedColumns(t *testing.T) {
 		assert.False(t, acc.HasMeasurement(col))
 	}
 }
+
+func TestPostgresqlDatabaseWhitelistTest(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping integration test in short mode")
+	}
+
+	p := &Postgresql{
+		Address: fmt.Sprintf("host=%s user=postgres sslmode=disable",
+			testutil.GetLocalHost()),
+		Databases: []string{"template0"},
+	}
+
+	var acc testutil.Accumulator
+
+	err := p.Gather(&acc)
+	require.NoError(t, err)
+
+	var foundTemplate0 = false
+	var foundTemplate1 = false
+
+	for _, pnt := range acc.Metrics {
+		if pnt.Measurement == "postgresql" {
+			if pnt.Tags["db"] == "template0" {
+				foundTemplate0 = true
+			}
+		}
+		if pnt.Measurement == "postgresql" {
+			if pnt.Tags["db"] == "template1" {
+				foundTemplate1 = true
+			}
+		}
+	}
+
+	assert.True(t, foundTemplate0)
+	assert.False(t, foundTemplate1)
+}
+
+func TestPostgresqlDatabaseBlacklistTest(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping integration test in short mode")
+	}
+
+	p := &Postgresql{
+		Address: fmt.Sprintf("host=%s user=postgres sslmode=disable",
+			testutil.GetLocalHost()),
+		IgnoredDatabases: []string{"template0"},
+	}
+
+	var acc testutil.Accumulator
+
+	err := p.Gather(&acc)
+	require.NoError(t, err)
+
+	var foundTemplate0 = false
+	var foundTemplate1 = false
+
+	for _, pnt := range acc.Metrics {
+		if pnt.Measurement == "postgresql" {
+			if pnt.Tags["db"] == "template0" {
+				foundTemplate0 = true
+			}
+		}
+		if pnt.Measurement == "postgresql" {
+			if pnt.Tags["db"] == "template1" {
+				foundTemplate1 = true
+			}
+		}
+	}
+
+	assert.False(t, foundTemplate0)
+	assert.True(t, foundTemplate1)
+}