Enhance docs and test

docs/sources/flow/reference/components/prometheus.exporter.postgres.md

@@ -32,18 +32,35 @@ prometheus.exporter.postgres "LABEL" {
 The following arguments are supported:
 
 | Name                         | Type           | Description                                                                   | Default | Required |
-| ---------------------------- | -------------- | ----------------------------------------------------------------------------- | ------- | -------- |
+|------------------------------|----------------|-------------------------------------------------------------------------------|---------|----------|
 | `data_source_names`          | `list(secret)` | Specifies the Postgres server(s) to connect to.                               |         | yes      |
 | `disable_settings_metrics`   | `bool`         | Disables collection of metrics from pg_settings.                              | `false` | no       |
 | `disable_default_metrics`    | `bool`         | When `true`, only exposes metrics supplied from `custom_queries_config_path`. | `false` | no       |
 | `custom_queries_config_path` | `string`       | Path to YAML file containing custom queries to expose as metrics.             | ""      | no       |
+| `enabled_collectors`         | `list(string)` | List of collectors to enable. See below for more detail.                      | []      | no       |
 
 The format for connection strings in `data_source_names` can be found in the [official postgresql documentation](https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNSTRING).
 
 See examples for the `custom_queries_config_path` file in the [postgres_exporter repository](https://github.com/prometheus-community/postgres_exporter/blob/master/queries.yaml).
 
 **NOTE**: There are a number of environment variables that are not recommended for use, as they will affect _all_ `prometheus.exporter.postgres` components. A full list can be found in the [postgres_exporter repository](https://github.com/prometheus-community/postgres_exporter#environment-variables).
 
+By default, the same set of metrics is enabled as in the upstream [postgres_exporter](https://github.com/prometheus-community/postgres_exporter/). If `custom_queries_config_path` is set, additional metrics defined in the given config file will be exposed.
+If `disable_default_metrics` is set to `true`, only the metrics defined in the `custom_queries_config_path` file will be exposed.
+
+A subset of metrics collectors can be controlled by setting the `enabled_collectors` argument. The following collectors are available for selection:
+`database`, `database_wraparound`, `locks`, `long_running_transactions`, `postmaster`, `process_idle`,
+`replication`, `replication_slot`, `stat_activity_autovacuum`, `stat_bgwriter`, `stat_database`,
+`stat_statements`, `stat_user_tables`, `stat_wal_receiver`, `statio_user_indexes`, `statio_user_tables`,
+`wal`, `xlog_location`.
+
+By default, the following collectors are enabled: `database`, `locks`, `replication`, `replication_slot`, `stat_bgwriter`, `stat_database`,
+`stat_user_tables`, `statio_user_tables`, `wal`.
+
+{{< admonition type="note" >}}
+Due to a limitation of the upstream exporter, when multiple `data_source_names` are used, the collectors that are controlled via the `enabled_collectors` argument will only be applied to the first data source in the list.
+{{< /admonition >}}
+
 ## Blocks
 
 The following blocks are supported:

internal/component/prometheus/exporter/postgres/postgres.go

@@ -27,7 +27,7 @@ func init() {
 
 func createExporter(opts component.Options, args component.Arguments, defaultInstanceKey string) (integrations.Integration, string, error) {
 	a := args.(Arguments)
-	return integrations.NewIntegrationWithInstanceKey(opts.Logger, a.Convert(), defaultInstanceKey)
+	return integrations.NewIntegrationWithInstanceKey(opts.Logger, a.convert(opts.ID), defaultInstanceKey)
 }
 
 func parsePostgresURL(url string) (map[string]string, error) {
@@ -83,7 +83,6 @@ type Arguments struct {
 	DisableSettingsMetrics  bool     `river:"disable_settings_metrics,attr,optional"`
 	DisableDefaultMetrics   bool     `river:"disable_default_metrics,attr,optional"`
 	CustomQueriesConfigPath string   `river:"custom_queries_config_path,attr,optional"`
-	Instance                string   `river:"instance,attr,optional"`
 	EnabledCollectors       []string `river:"enabled_collectors,attr,optional"`
 
 	// Blocks
@@ -112,7 +111,7 @@ func (a *Arguments) SetToDefault() {
 	*a = DefaultArguments
 }
 
-func (a *Arguments) Convert() *postgres_exporter.Config {
+func (a *Arguments) convert(instanceName string) *postgres_exporter.Config {
 	return &postgres_exporter.Config{
 		DataSourceNames:        a.convertDataSourceNames(),
 		DisableSettingsMetrics: a.DisableSettingsMetrics,
@@ -121,7 +120,7 @@ func (a *Arguments) Convert() *postgres_exporter.Config {
 		IncludeDatabases:       a.AutoDiscovery.DatabaseAllowlist,
 		DisableDefaultMetrics:  a.DisableDefaultMetrics,
 		QueryPath:              a.CustomQueriesConfigPath,
-		Instance:               a.Instance,
+		Instance:               instanceName,
 		EnabledCollectors:      a.EnabledCollectors,
 	}
 }

internal/component/prometheus/exporter/postgres/postgres_test.go

@@ -46,8 +46,9 @@ func TestRiverConfigConvert(t *testing.T) {
 	var exampleRiverConfig = `
 	data_source_names = ["postgresql://username:password@localhost:5432/database?sslmode=disable"]
 	disable_settings_metrics = true
-	disable_default_metrics = true
+	disable_default_metrics = false
 	custom_queries_config_path = "/tmp/queries.yaml"
+	enabled_collectors = ["collector1", "collector2"]
 	
 	autodiscovery {
 		enabled = false
@@ -59,16 +60,18 @@ func TestRiverConfigConvert(t *testing.T) {
 	err := river.Unmarshal([]byte(exampleRiverConfig), &args)
 	require.NoError(t, err)
 
-	c := args.Convert()
+	c := args.convert("test-instance")
 
 	expected := postgres_exporter.Config{
 		DataSourceNames:        []config_util.Secret{config_util.Secret("postgresql://username:password@localhost:5432/database?sslmode=disable")},
 		DisableSettingsMetrics: true,
 		AutodiscoverDatabases:  false,
 		ExcludeDatabases:       []string{"exclude1", "exclude2"},
 		IncludeDatabases:       []string{"include1"},
-		DisableDefaultMetrics:  true,
+		DisableDefaultMetrics:  false,
 		QueryPath:              "/tmp/queries.yaml",
+		Instance:               "test-instance",
+		EnabledCollectors:      []string{"collector1", "collector2"},
 	}
 	require.Equal(t, expected, *c)
 }