fix(agent): watch for changes in configuration files in config directories (#12127)

cmd/telegraf/telegraf.go

@@ -62,6 +62,7 @@ type Telegraf struct {
 
 	inputFilters  []string
 	outputFilters []string
+	configFiles   []string
 
 	GlobalFlags
 	WindowFlags
@@ -86,7 +87,7 @@ func (t *Telegraf) reloadLoop() error {
 		signal.Notify(signals, os.Interrupt, syscall.SIGHUP,
 			syscall.SIGTERM, syscall.SIGINT)
 		if t.watchConfig != "" {
-			for _, fConfig := range t.config {
+			for _, fConfig := range t.configFiles {
 				if _, err := os.Stat(fConfig); err == nil {
 					go t.watchLocalConfig(signals, fConfig)
 				} else {
@@ -161,30 +162,30 @@ func (t *Telegraf) watchLocalConfig(signals chan os.Signal, fConfig string) {
 }
 
 func (t *Telegraf) runAgent(ctx context.Context) error {
+	var configFiles []string
+	// providing no "config" flag should load default config
+	if len(t.config) == 0 {
+		configFiles = append(configFiles, "")
+	} else {
+		configFiles = append(configFiles, t.config...)
+	}
+
+	for _, fConfigDirectory := range t.configDir {
+		files, err := config.WalkDirectory(fConfigDirectory)
+		if err != nil {
+			return err
+		}
+		configFiles = append(configFiles, files...)
+	}
+
 	// If no other options are specified, load the config file and run.
 	c := config.NewConfig()
 	c.OutputFilters = t.outputFilters
 	c.InputFilters = t.inputFilters
-	var err error
-	// providing no "config" flag should load default config
-	if len(t.config) == 0 {
-		err = c.LoadConfig("")
-		if err != nil {
-			return err
-		}
-	}
-	for _, fConfig := range t.config {
-		err = c.LoadConfig(fConfig)
-		if err != nil {
-			return err
-		}
-	}
 
-	for _, fConfigDirectory := range t.configDir {
-		err = c.LoadDirectory(fConfigDirectory)
-		if err != nil {
-			return err
-		}
+	t.configFiles = configFiles
+	if err := c.LoadAll(configFiles...); err != nil {
+		return err
 	}
 
 	if !(t.test || t.testWait != 0) && len(c.Outputs) == 0 {
@@ -215,7 +216,7 @@ func (t *Telegraf) runAgent(ctx context.Context) error {
 		LogWithTimezone:     c.Agent.LogWithTimezone,
 	}
 
-	err = logger.SetupLogging(logConfig)
+	err := logger.SetupLogging(logConfig)
 	if err != nil {
 		return err
 	}

config/config.go

@@ -301,8 +301,9 @@ func sliceContains(name string, list []string) bool {
 	return false
 }
 
-// LoadDirectory loads all toml config files found in the specified path, recursively.
-func (c *Config) LoadDirectory(path string) error {
+// WalkDirectory collects all toml files that need to be loaded
+func WalkDirectory(path string) ([]string, error) {
+	var files []string
 	walkfn := func(thispath string, info os.FileInfo, _ error) error {
 		if info == nil {
 			log.Printf("W! Telegraf is not permitted to read %s", thispath)
@@ -311,7 +312,7 @@ func (c *Config) LoadDirectory(path string) error {
 
 		if info.IsDir() {
 			if strings.HasPrefix(info.Name(), "..") {
-				// skip Kubernetes mounts, prevening loading the same config twice
+				// skip Kubernetes mounts, preventing loading the same config twice
 				return filepath.SkipDir
 			}
 
@@ -321,13 +322,10 @@ func (c *Config) LoadDirectory(path string) error {
 		if len(name) < 6 || name[len(name)-5:] != ".conf" {
 			return nil
 		}
-		err := c.LoadConfig(thispath)
-		if err != nil {
-			return err
-		}
+		files = append(files, thispath)
 		return nil
 	}
-	return filepath.Walk(path, walkfn)
+	return files, filepath.Walk(path, walkfn)
 }
 
 // Try to find a default config file at these locations (in order):
@@ -386,6 +384,16 @@ func (c *Config) LoadConfig(path string) error {
 	return nil
 }
 
+func (c *Config) LoadAll(configFiles ...string) error {
+	for _, fConfig := range configFiles {
+		if err := c.LoadConfig(fConfig); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
 // LoadConfigData loads TOML-formatted config data
 func (c *Config) LoadConfigData(data []byte) error {
 	tbl, err := parseConfig(data)

config/config_test.go

@@ -140,8 +140,11 @@ func TestConfig_LoadSingleInput(t *testing.T) {
 
 func TestConfig_LoadDirectory(t *testing.T) {
 	c := NewConfig()
-	require.NoError(t, c.LoadConfig("./testdata/single_plugin.toml"))
-	require.NoError(t, c.LoadDirectory("./testdata/subconfig"))
+
+	files, err := WalkDirectory("./testdata/subconfig")
+	files = append([]string{"./testdata/single_plugin.toml"}, files...)
+	require.NoError(t, err)
+	require.NoError(t, c.LoadAll(files...))
 
 	// Create the expected data
 	expectedPlugins := make([]*MockupInputPlugin, 4)