[-] fix source config update handling

cmd/pgwatch/main_integration_test.go

@@ -204,3 +204,270 @@ metrics:
 		assert.GreaterOrEqual(t, count, len(specialNames), "expected metrics to be stored in test_metric table")
 	})
 }
+
+// TestMain_Integration_ConfigChanges tests that source configuration changes
+// are properly applied to running gatherers
+func TestMain_Integration_ConfigChanges(t *testing.T) {
+	tempDir := t.TempDir()
+
+	pg, tearDown, err := testutil.SetupPostgresContainer()
+	require.NoError(t, err)
+	defer tearDown()
+
+	connStr, err := pg.ConnectionString(testutil.TestContext, "sslmode=disable")
+	require.NoError(t, err)
+
+	var gotExit int32
+	Exit = func(code int) { gotExit = int32(code) }
+	defer func() { Exit = os.Exit }()
+
+	metricsYaml := filepath.Join(tempDir, "metrics.yaml")
+	sourcesYaml := filepath.Join(tempDir, "sources.yaml")
+
+	require.NoError(t, os.WriteFile(metricsYaml, []byte(`
+metrics:
+    test_metric:
+        sqls:
+            11: select (extract(epoch from now()) * 1e9)::int8 as epoch_ns, 1 as value
+presets:
+    test_preset:
+        metrics:
+            test_metric: 1
+`), 0644))
+
+	require.NoError(t, os.WriteFile(sourcesYaml, []byte(`
+- name: test_source
+  conn_str: `+connStr+`
+  kind: postgres
+  is_enabled: true
+  custom_tags:
+    environment: production
+    version: "1.0"
+  custom_metrics:
+    test_metric: 1
+`), 0644))
+
+	os.Args = []string{
+		"pgwatch",
+		"--metrics", metricsYaml,
+		"--sources", sourcesYaml,
+		"--sink", connStr,
+		"--refresh=2",
+		"--web-disable",
+	}
+
+	sinkConn, err := pgx.Connect(context.Background(), connStr)
+	require.NoError(t, err)
+	defer sinkConn.Close(context.Background())
+
+	go main()
+
+	// Below tests are expected to run sequentially and depend on 
+	// data generated by each other
+
+	t.Run("Ensure tag changes are applied", func(t *testing.T) {
+		// Wait for some initial metrics to be written
+		time.Sleep(2 * time.Second)
+
+		var tagData map[string]string
+		err = sinkConn.QueryRow(context.Background(),
+			`SELECT tag_data FROM test_metric 
+			 WHERE dbname = 'test_source' 
+			 ORDER BY time DESC LIMIT 1`).Scan(&tagData)
+		require.NoError(t, err)
+		assert.Equal(t, "production", tagData["environment"], "initial environment tag should be 'production'")
+		assert.Equal(t, "1.0", tagData["version"], "initial version tag should be '1.0'")
+
+		// Update custom_tags
+		require.NoError(t, os.WriteFile(sourcesYaml, []byte(`
+- name: test_source
+  conn_str: `+connStr+`
+  kind: postgres
+  is_enabled: true
+  custom_tags:
+    environment: staging
+    version: "2.0"
+    new_tag: added
+  custom_metrics:
+    test_metric: 1
+`), 0644))
+
+		// Wait for config reload and new metrics with updated tags
+		time.Sleep(3 * time.Second)
+
+		err = sinkConn.QueryRow(context.Background(),
+			`SELECT tag_data FROM test_metric 
+			 WHERE dbname = 'test_source' 
+			 ORDER BY time DESC LIMIT 1`).Scan(&tagData)
+		require.NoError(t, err)
+		assert.Equal(t, "staging", tagData["environment"], "updated environment tag should be 'staging'")
+		assert.Equal(t, "2.0", tagData["version"], "updated version tag should be '2.0'")
+		assert.Equal(t, "added", tagData["new_tag"], "new_tag should be present")
+	})
+
+	t.Run("Ensure metric interval changes are applied", func(t *testing.T) {
+		// Get collection interval before change
+		var epochNsBefore []int64
+		rows, err := sinkConn.Query(context.Background(),
+			`SELECT (data->>'epoch_ns')::bigint as epoch_ns 
+			 FROM test_metric 
+			 WHERE dbname = 'test_source' 
+			 ORDER BY time DESC LIMIT 2`)
+		require.NoError(t, err)
+		for rows.Next() {
+			var epochNs int64
+			require.NoError(t, rows.Scan(&epochNs))
+			epochNsBefore = append(epochNsBefore, epochNs)
+		}
+		rows.Close()
+		require.GreaterOrEqual(t, len(epochNsBefore), 2, "we need at least 2 measurements")
+
+		// Calculate interval before change
+		intervalBefore := float64(epochNsBefore[0] - epochNsBefore[1]) / 1e9
+		assert.InDelta(t, 1.0, intervalBefore, 0.5, "interval should be approximately 1 second")
+
+		// Change interval to 2 seconds
+		require.NoError(t, os.WriteFile(sourcesYaml, []byte(`
+- name: test_source
+  conn_str: `+connStr+`
+  kind: postgres
+  is_enabled: true
+  custom_metrics:
+    test_metric: 2
+`), 0644))
+
+		time.Sleep(5 * time.Second)
+
+		// Get collection interval after change
+		var epochNsAfter []int64
+		rows, err = sinkConn.Query(context.Background(),
+			`SELECT (data->>'epoch_ns')::bigint as epoch_ns 
+			 FROM test_metric 
+			 WHERE dbname = 'test_source' 
+			 ORDER BY time DESC LIMIT 2`)
+		require.NoError(t, err)
+		for rows.Next() {
+			var epochNs int64
+			require.NoError(t, rows.Scan(&epochNs))
+			epochNsAfter = append(epochNsAfter, epochNs)
+		}
+		rows.Close()
+		require.GreaterOrEqual(t, len(epochNsAfter), 2, "we need at least 2 measurements after interval change")
+
+		// Calculate interval after change
+		intervalAfter := float64(epochNsAfter[0] - epochNsAfter[1]) / 1e9
+		assert.InDelta(t, 2.0, intervalAfter, 0.5, "new interval should be approximately 2 seconds")
+		assert.Greater(t, intervalAfter, intervalBefore, "new interval should be greater than old interval")
+	})
+
+	t.Run("Ensure conn str changes are applied", func(t *testing.T) {
+		// Count rows before connection string change
+		var countBefore int
+		err = sinkConn.QueryRow(context.Background(),
+			`SELECT count(*) FROM test_metric WHERE dbname = 'test_source'`).Scan(&countBefore)
+		require.NoError(t, err)
+		require.Greater(t, countBefore, 0)
+
+		// Change to invalid connection string
+		require.NoError(t, os.WriteFile(sourcesYaml, []byte(`
+- name: test_source
+  conn_str: postgres://invalid:invalid@localhost:59999/nonexistent
+  kind: postgres
+  is_enabled: true
+  custom_metrics:
+    test_metric: 1
+`), 0644))
+
+		// Wait for config reload and failed metric fetches
+		time.Sleep(4 * time.Second)
+
+		// Count rows after connection string change
+		var countAfter int
+		err = sinkConn.QueryRow(context.Background(),
+			`SELECT count(*) FROM public.test_metric WHERE dbname = 'test_source'`).Scan(&countAfter)
+		require.NoError(t, err)
+
+		assert.LessOrEqual(t, countAfter - countBefore, 2)
+	})
+
+	t.Run("Ensure preset intervals updates are applied - issue #1091", func(t *testing.T) {
+		require.NoError(t, os.WriteFile(sourcesYaml, []byte(`
+- name: test_source
+  conn_str: `+connStr+`
+  kind: postgres
+  is_enabled: true
+  custom_tags:
+    version: "1.0"
+  preset_metrics: test_preset
+`), 0644))
+
+		// Wait for reload and some metrics collection
+		time.Sleep(4 * time.Second)
+
+		var epochNsBefore []int64
+		rows, err := sinkConn.Query(context.Background(),
+			`SELECT (data->>'epoch_ns')::bigint as epoch_ns 
+			 FROM public.test_metric 
+			 WHERE dbname = 'test_source' 
+			 ORDER BY time DESC LIMIT 2`)
+		require.NoError(t, err)
+		for rows.Next() {
+			var epochNs int64
+			require.NoError(t, rows.Scan(&epochNs))
+			epochNsBefore = append(epochNsBefore, epochNs)
+		}
+		rows.Close()
+		require.GreaterOrEqual(t, len(epochNsBefore), 2, "should have at least 2 measurements")
+
+		// Calculate interval before change
+		intervalBefore := float64(epochNsBefore[0] - epochNsBefore[1]) / 1e9
+		assert.InDelta(t, 1.0, intervalBefore, 0.5, "interval should be approximately 1 second")
+
+		require.NoError(t, os.WriteFile(sourcesYaml, []byte(`
+- name: test_source
+  conn_str: `+connStr+`
+  kind: postgres
+  is_enabled: true
+  custom_tags:
+    version: "2.0" # to force a reload - triggering the bug
+  preset_metrics: test_preset
+`), 0644))
+
+		require.NoError(t, os.WriteFile(metricsYaml, []byte(`
+metrics:
+    test_metric:
+        sqls:
+            11: select (extract(epoch from now()) * 1e9)::int8 as epoch_ns, 1 as value
+presets:
+    test_preset:
+        metrics:
+            test_metric: 2
+`), 0644))
+
+		// Wait for config reload and some metrics
+		time.Sleep(5 * time.Second)
+
+		var epochNsAfter []int64
+		rows, err = sinkConn.Query(context.Background(),
+			`SELECT (data->>'epoch_ns')::bigint as epoch_ns 
+			 FROM public.test_metric 
+			 WHERE dbname = 'test_source' 
+			 ORDER BY time DESC LIMIT 2`)
+		require.NoError(t, err)
+		for rows.Next() {
+			var epochNs int64
+			require.NoError(t, rows.Scan(&epochNs))
+			epochNsAfter = append(epochNsAfter, epochNs)
+		}
+		rows.Close()
+		require.GreaterOrEqual(t, len(epochNsAfter), 2, "should have at least 2 measurements")
+
+		// Calculate interval after change
+		intervalAfter := float64(epochNsAfter[0] - epochNsAfter[1]) / 1e9
+		assert.InDelta(t, 2.0, intervalAfter, 0.5, "interval should be approximately 2 seconds")
+	})
+
+	cancel()
+	<-mainCtx.Done()
+	assert.Equal(t, cmdopts.ExitCodeOK, gotExit)
+}

internal/reaper/database.go

@@ -527,18 +527,18 @@ func TryCreateMetricsFetchingHelpers(ctx context.Context, md *sources.SourceConn
 	return
 }
 
-func (r *Reaper) CloseResourcesForRemovedMonitoredDBs(shutDownDueToRoleChange map[string]bool) {
+func (r *Reaper) CloseResourcesForRemovedMonitoredDBs(hostsToShutDown map[string]bool) {
 	for _, prevDB := range r.prevLoopMonitoredDBs {
 		if r.monitoredSources.GetMonitoredDatabase(prevDB.Name) == nil { // removed from config
 			prevDB.Conn.Close()
 			_ = r.SinksWriter.SyncMetric(prevDB.Name, "", sinks.DeleteOp)
 		}
 	}
 
-	for roleChangedDB := range shutDownDueToRoleChange {
-		if db := r.monitoredSources.GetMonitoredDatabase(roleChangedDB); db != nil {
+	for toShutDownDB := range hostsToShutDown {
+		if db := r.monitoredSources.GetMonitoredDatabase(toShutDownDB); db != nil {
 			db.Conn.Close()
 		}
-		_ = r.SinksWriter.SyncMetric(roleChangedDB, "", sinks.DeleteOp)
+		_ = r.SinksWriter.SyncMetric(toShutDownDB, "", sinks.DeleteOp)
 	}
 }

internal/reaper/reaper.go

@@ -88,7 +88,7 @@ func (r *Reaper) Reap(ctx context.Context) {
 		if r.Logging.LogLevel == "debug" {
 			r.PrintMemStats()
 		}
-		if err = r.LoadSources(); err != nil {
+		if err = r.LoadSources(ctx); err != nil {
 			logger.WithError(err).Error("could not refresh active sources, using last valid cache")
 		}
 		if err = r.LoadMetrics(); err != nil {
@@ -232,7 +232,7 @@ func (r *Reaper) CreateSourceHelpers(ctx context.Context, srcL log.Logger, monit
 
 }
 
-func (r *Reaper) ShutdownOldWorkers(ctx context.Context, hostsToShutDownDueToRoleChange map[string]bool) {
+func (r *Reaper) ShutdownOldWorkers(ctx context.Context, hostsToShutDown map[string]bool) {
 	logger := r.logger
 	// loop over existing channels and stop workers if DB or metric removed from config
 	// or state change makes it uninteresting
@@ -241,31 +241,36 @@ func (r *Reaper) ShutdownOldWorkers(ctx context.Context, hostsToShutDownDueToRol
 		var currentMetricConfig map[string]float64
 		var md *sources.SourceConn
 		var dbRemovedFromConfig bool
-		singleMetricDisabled := false
+		var metricRemovedFromPreset bool
 		splits := strings.Split(dbMetric, dbMetricJoinStr)
 		db := splits[0]
 		metric := splits[1]
 
-		_, wholeDbShutDownDueToRoleChange := hostsToShutDownDueToRoleChange[db]
-		if !wholeDbShutDownDueToRoleChange {
+		_, wholeDbShutDown := hostsToShutDown[db]
+		if !wholeDbShutDown {
 			md = r.monitoredSources.GetMonitoredDatabase(db)
 			if md == nil { // normal removing of DB from config
 				dbRemovedFromConfig = true
 				logger.Debugf("DB %s removed from config, shutting down all metric worker processes...", db)
 			}
 		}
 
-		if !(wholeDbShutDownDueToRoleChange || dbRemovedFromConfig) { // maybe some single metric was disabled
+		// Detects metrics removed from a preset definition.
+		//
+		// If not using presets, a metric removed from configs will
+		// be detected earlier by `LoadSources()` as configs change that 
+		// triggers a restart and get passed in `hostsToShutDown`.
+		if !(wholeDbShutDown || dbRemovedFromConfig) {
 			if md.IsInRecovery && len(md.MetricsStandby) > 0 {
 				currentMetricConfig = md.MetricsStandby
 			} else {
 				currentMetricConfig = md.Metrics
 			}
 			interval, isMetricActive := currentMetricConfig[metric]
-			singleMetricDisabled = !isMetricActive || interval <= 0
+			metricRemovedFromPreset = !isMetricActive || interval <= 0
 		}
 
-		if ctx.Err() != nil || wholeDbShutDownDueToRoleChange || dbRemovedFromConfig || singleMetricDisabled {
+		if ctx.Err() != nil || wholeDbShutDown || dbRemovedFromConfig || metricRemovedFromPreset {
 			logger.WithField("source", db).WithField("metric", metric).Info("stopping gatherer...")
 			cancelFunc()
 			delete(r.cancelFuncs, dbMetric)
@@ -276,7 +281,7 @@ func (r *Reaper) ShutdownOldWorkers(ctx context.Context, hostsToShutDownDueToRol
 	}
 
 	// Destroy conn pools and metric writers
-	r.CloseResourcesForRemovedMonitoredDBs(hostsToShutDownDueToRoleChange)
+	r.CloseResourcesForRemovedMonitoredDBs(hostsToShutDown)
 }
 
 func (r *Reaper) reapMetricMeasurements(ctx context.Context, md *sources.SourceConn, metricName string) {
@@ -379,7 +384,7 @@ func (r *Reaper) reapMetricMeasurements(ctx context.Context, md *sources.SourceC
 }
 
 // LoadSources loads sources from the reader
-func (r *Reaper) LoadSources() (err error) {
+func (r *Reaper) LoadSources(ctx context.Context) (err error) {
 	if DoesEmergencyTriggerfileExist(r.Metrics.EmergencyPauseTriggerfile) {
 		r.logger.Warningf("Emergency pause triggerfile detected at %s, ignoring currently configured DBs", r.Metrics.EmergencyPauseTriggerfile)
 		r.monitoredSources = make(sources.SourceConns, 0)
@@ -408,6 +413,10 @@ func (r *Reaper) LoadSources() (err error) {
 			newSrcs[i] = md
 			continue
 		}
+		// Source configs changed, stop all running gatherers to trigger a restart
+		// TODO: Optimize this for single metric addition/deletion/interval-change cases to not do a full restart
+		r.logger.WithField("source", md.Name).Info("Source configs changed, restarting all gatherers...")
+		r.ShutdownOldWorkers(ctx, map[string]bool{md.Name: true})
 	}
 	r.monitoredSources = newSrcs
 	r.logger.WithField("sources", len(r.monitoredSources)).Info("sources refreshed")