feat(outputs.postgresql): Allow configuration of startup error handling (#15073)

plugins/outputs/postgresql/README.md

@@ -12,6 +12,20 @@ See the [CONFIGURATION.md][CONFIGURATION.md] for more details.
 
 [CONFIGURATION.md]: ../../../docs/CONFIGURATION.md#plugins
 
+## Startup error behavior options <!-- @/docs/includes/startup_error_behavior.md -->
+
+In addition to the plugin-specific and global configuration settings the plugin
+supports options for specifying the behavior when experiencing startup errors
+using the `startup_error_behavior` setting. Available values are:
+
+- `error`:  Telegraf with stop and exit in case of startup errors. This is the
+            default behavior.
+- `ignore`: Telegraf will ignore startup errors for this plugin and disables it
+            but continues processing for all other plugins.
+- `retry`:  Telegraf will try to startup the plugin in every gather or write
+            cycle in case of startup errors. The plugin is disabled until
+            the startup succeeds.
+
 ## Secret-store support
 
 This plugin supports secrets from secret-stores for the `connection` option.

plugins/outputs/postgresql/postgresql.go

@@ -17,6 +17,7 @@ import (
 
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/config"
+	"github.com/influxdata/telegraf/internal"
 	"github.com/influxdata/telegraf/models"
 	"github.com/influxdata/telegraf/plugins/outputs"
 	"github.com/influxdata/telegraf/plugins/outputs/postgresql/sqltemplate"
@@ -72,33 +73,8 @@ type Postgresql struct {
 	tagsJSONColumn   utils.Column
 }
 
-func init() {
+func (p *Postgresql) SampleConfig() string {
-	outputs.Add("postgresql", func() telegraf.Output { return newPostgresql() })
+	return sampleConfig
-}
-
-func newPostgresql() *Postgresql {
-	p := &Postgresql{
-		Schema:                     "public",
-		TagTableSuffix:             "_tag",
-		TagCacheSize:               100000,
-		Uint64Type:                 PgNumeric,
-		CreateTemplates:            []*sqltemplate.Template{{}},
-		AddColumnTemplates:         []*sqltemplate.Template{{}},
-		TagTableCreateTemplates:    []*sqltemplate.Template{{}},
-		TagTableAddColumnTemplates: []*sqltemplate.Template{{}},
-		RetryMaxBackoff:            config.Duration(time.Second * 15),
-		Logger:                     models.NewLogger("outputs", "postgresql", ""),
-		LogLevel:                   "warn",
-	}
-
-	_ = p.CreateTemplates[0].UnmarshalText([]byte(`CREATE TABLE {{ .table }} ({{ .columns }})`))
-	_ = p.AddColumnTemplates[0].UnmarshalText([]byte(`ALTER TABLE {{ .table }} ADD COLUMN IF NOT EXISTS {{ .columns|join ", ADD COLUMN IF NOT EXISTS " }}`))
-	_ = p.TagTableCreateTemplates[0].UnmarshalText([]byte(`CREATE TABLE {{ .table }} ({{ .columns }}, PRIMARY KEY (tag_id))`))
-	_ = p.TagTableAddColumnTemplates[0].UnmarshalText(
-		[]byte(`ALTER TABLE {{ .table }} ADD COLUMN IF NOT EXISTS {{ .columns|join ", ADD COLUMN IF NOT EXISTS " }}`),
-	)
-
-	return p
 }
 
 func (p *Postgresql) Init() error {
@@ -169,8 +145,6 @@ func (p *Postgresql) Init() error {
 	return nil
 }
 
-func (p *Postgresql) SampleConfig() string { return sampleConfig }
-
 // Connect establishes a connection to the target database and prepares the cache
 func (p *Postgresql) Connect() error {
 	// Yes, we're not supposed to store the context. However since we don't receive a context, we have to.
@@ -178,8 +152,11 @@ func (p *Postgresql) Connect() error {
 	var err error
 	p.db, err = pgxpool.ConnectConfig(p.dbContext, p.dbConfig)
 	if err != nil {
-		p.Logger.Errorf("Couldn't connect to server\n%v", err)
+		p.dbContextCancel()
-		return err
+		return &internal.StartupError{
+			Err:   err,
+			Retry: true,
+		}
 	}
 	p.tableManager = NewTableManager(p)
 
@@ -234,7 +211,9 @@ func (p *Postgresql) Close() error {
 
 	// Die!
 	p.dbContextCancel()
-	p.db.Close()
+	if p.db != nil {
+		p.db.Close()
+	}
 	p.tableManager = nil
 	return nil
 }
@@ -493,3 +472,32 @@ func (p *Postgresql) writeTagTable(ctx context.Context, db dbh, tableSource *Tab
 	ttsrc.UpdateCache()
 	return nil
 }
+
+func newPostgresql() *Postgresql {
+	p := &Postgresql{
+		Schema:                     "public",
+		TagTableSuffix:             "_tag",
+		TagCacheSize:               100000,
+		Uint64Type:                 PgNumeric,
+		CreateTemplates:            []*sqltemplate.Template{{}},
+		AddColumnTemplates:         []*sqltemplate.Template{{}},
+		TagTableCreateTemplates:    []*sqltemplate.Template{{}},
+		TagTableAddColumnTemplates: []*sqltemplate.Template{{}},
+		RetryMaxBackoff:            config.Duration(time.Second * 15),
+		Logger:                     models.NewLogger("outputs", "postgresql", ""),
+		LogLevel:                   "warn",
+	}
+
+	_ = p.CreateTemplates[0].UnmarshalText([]byte(`CREATE TABLE {{ .table }} ({{ .columns }})`))
+	_ = p.AddColumnTemplates[0].UnmarshalText([]byte(`ALTER TABLE {{ .table }} ADD COLUMN IF NOT EXISTS {{ .columns|join ", ADD COLUMN IF NOT EXISTS " }}`))
+	_ = p.TagTableCreateTemplates[0].UnmarshalText([]byte(`CREATE TABLE {{ .table }} ({{ .columns }}, PRIMARY KEY (tag_id))`))
+	_ = p.TagTableAddColumnTemplates[0].UnmarshalText(
+		[]byte(`ALTER TABLE {{ .table }} ADD COLUMN IF NOT EXISTS {{ .columns|join ", ADD COLUMN IF NOT EXISTS " }}`),
+	)
+
+	return p
+}
+
+func init() {
+	outputs.Add("postgresql", func() telegraf.Output { return newPostgresql() })
+}

plugins/outputs/postgresql/postgresql_test.go

@@ -18,7 +18,9 @@ import (
 
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/config"
+	"github.com/influxdata/telegraf/internal"
 	"github.com/influxdata/telegraf/metric"
+	"github.com/influxdata/telegraf/models"
 	"github.com/influxdata/telegraf/plugins/outputs/postgresql/utils"
 	"github.com/influxdata/telegraf/testutil"
 )
@@ -272,6 +274,80 @@ func TestPostgresqlConnectIntegration(t *testing.T) {
 	require.EqualValues(t, 2, p.db.Stat().MaxConns())
 }
 
+func TestConnectionIssueAtStartup(t *testing.T) {
+	// Test case for https://github.com/influxdata/telegraf/issues/14365
+	if testing.Short() {
+		t.Skip("Skipping integration test in short mode")
+	}
+
+	servicePort := "5432"
+	username := "postgres"
+	password := "postgres"
+	testDatabaseName := "telegraf_test"
+
+	container := testutil.Container{
+		Image:        "postgres:alpine",
+		ExposedPorts: []string{servicePort},
+		Env: map[string]string{
+			"POSTGRES_USER":     username,
+			"POSTGRES_PASSWORD": password,
+			"POSTGRES_DB":       "telegraf_test",
+		},
+		WaitingFor: wait.ForAll(
+			// the database comes up twice, once right away, then again a second
+			// time after the docker entrypoint starts configuration
+			wait.ForLog("database system is ready to accept connections").WithOccurrence(2),
+			wait.ForListeningPort(nat.Port(servicePort)),
+		),
+	}
+	require.NoError(t, container.Start(), "failed to start container")
+	defer container.Terminate()
+
+	// Pause the container for connectivity issues
+	require.NoError(t, container.Pause())
+
+	// Create a model to be able to use the startup retry strategy
+	dsn := config.NewSecret([]byte(fmt.Sprintf(
+		"host=%s port=%s user=%s password=%s dbname=%s  connect_timeout=1",
+		container.Address,
+		container.Ports[servicePort],
+		username,
+		password,
+		testDatabaseName,
+	)))
+	defer dsn.Destroy()
+	plugin := newPostgresql()
+	plugin.Connection = dsn
+	plugin.Logger = NewLogAccumulator(t)
+	plugin.LogLevel = "debug"
+	model := models.NewRunningOutput(
+		plugin,
+		&models.OutputConfig{
+			Name:                 "postgres",
+			StartupErrorBehavior: "retry",
+		},
+		1000, 1000,
+	)
+	require.NoError(t, model.Init())
+
+	// The connect call should succeed even though the table creation was not
+	// successful due to the "retry" strategy
+	require.NoError(t, model.Connect())
+
+	// Writing the metrics in this state should fail because we are not fully
+	// started up
+	metrics := testutil.MockMetrics()
+	for _, m := range metrics {
+		model.AddMetric(m)
+	}
+	require.ErrorIs(t, model.WriteBatch(), internal.ErrNotConnected)
+
+	// Unpause the container, now writes should succeed
+	require.NoError(t, container.Resume())
+	require.NoError(t, model.WriteBatch())
+	model.Close()
+}
+
 func newMetric(
 	t *testing.T,
 	suffix string,