feat(inputs.execd): Add option to not restart program on error

internal/process/process.go

@@ -23,6 +23,7 @@ type Process struct {
 	ReadStdoutFn func(io.Reader)
 	ReadStderrFn func(io.Reader)
 	RestartDelay time.Duration
+	StopOnError  bool
 	Log          telegraf.Logger
 
 	name       string
@@ -31,6 +32,8 @@ type Process struct {
 	pid        int32
 	cancel     context.CancelFunc
 	mainLoopWg sync.WaitGroup
+
+	sync.Mutex
 }
 
 // New creates a new process wrapper
@@ -65,10 +68,10 @@ func (p *Process) Start() error {
 
 	p.mainLoopWg.Add(1)
 	go func() {
+		defer p.mainLoopWg.Done()
 		if err := p.cmdLoop(ctx); err != nil {
 			p.Log.Errorf("Process quit with message: %v", err)
 		}
-		p.mainLoopWg.Done()
 	}()
 
 	return nil
@@ -81,12 +84,24 @@ func (p *Process) Stop() {
 		p.cancel()
 	}
 	// close stdin so the app can shut down gracefully.
-	if err := p.Stdin.Close(); err != nil {
+	if err := p.Stdin.Close(); err != nil && !errors.Is(err, os.ErrClosed) {
 		p.Log.Errorf("Stdin closed with message: %v", err)
 	}
 	p.mainLoopWg.Wait()
 }
 
+func (p *Process) Pid() int {
+	pid := atomic.LoadInt32(&p.pid)
+	return int(pid)
+}
+
+func (p *Process) State() (state *os.ProcessState, running bool) {
+	p.Lock()
+	defer p.Unlock()
+
+	return p.Cmd.ProcessState, p.Cmd.ProcessState.ExitCode() == -1
+}
+
 func (p *Process) cmdStart() error {
 	p.Cmd = exec.Command(p.name, p.args...)
 
@@ -119,15 +134,13 @@ func (p *Process) cmdStart() error {
 	return nil
 }
 
-func (p *Process) Pid() int {
-	pid := atomic.LoadInt32(&p.pid)
-	return int(pid)
-}
-
 // cmdLoop watches an already running process, restarting it when appropriate.
 func (p *Process) cmdLoop(ctx context.Context) error {
 	for {
 		err := p.cmdWait(ctx)
+		if err != nil && p.StopOnError {
+			return err
+		}
 		if isQuitting(ctx) {
 			p.Log.Infof("Process %s shut down", p.Cmd.Path)
 			return nil
@@ -184,7 +197,9 @@ func (p *Process) cmdWait(ctx context.Context) error {
 		wg.Done()
 	}()
 
+	p.Lock()
 	err := p.Cmd.Wait()
+	p.Unlock()
 	processCancel()
 	wg.Wait()
 	return err

plugins/inputs/execd/README.md

@@ -56,20 +56,24 @@ See the [CONFIGURATION.md][CONFIGURATION.md] for more details.
   ##   "SIGHUP"  : Send a HUP signal. Not available on Windows. (not recommended)
   ##   "SIGUSR1" : Send a USR1 signal. Not available on Windows.
   ##   "SIGUSR2" : Send a USR2 signal. Not available on Windows.
-  signal = "none"
+  # signal = "none"
 
   ## Delay before the process is restarted after an unexpected termination
-  restart_delay = "10s"
+  # restart_delay = "10s"
 
   ## Buffer size used to read from the command output stream
   ## Optional parameter. Default is 64 Kib, minimum is 16 bytes
   # buffer_size = "64Kib"
 
+  ## Disable automatic restart of the program and stop if the program exits
+  ## with an error (i.e. non-zero error code)
+  # stop_on_error = false
+
   ## Data format to consume.
   ## Each data format has its own unique set of configuration options, read
   ## more about them here:
   ## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_INPUT.md
-  data_format = "influx"
+  # data_format = "influx"
 ```
 
 ## Example

plugins/inputs/execd/execd.go

@@ -25,10 +25,11 @@ var sampleConfig string
 type Execd struct {
 	Command      []string        `toml:"command"`
 	Environment  []string        `toml:"environment"`
+	BufferSize   config.Size     `toml:"buffer_size"`
 	Signal       string          `toml:"signal"`
 	RestartDelay config.Duration `toml:"restart_delay"`
+	StopOnError  bool            `toml:"stop_on_error"`
 	Log          telegraf.Logger `toml:"-"`
-	BufferSize   config.Size     `toml:"buffer_size"`
 
 	process      *process.Process
 	acc          telegraf.Accumulator
@@ -59,10 +60,11 @@ func (e *Execd) Start(acc telegraf.Accumulator) error {
 	if err != nil {
 		return fmt.Errorf("error creating new process: %w", err)
 	}
-	e.process.Log = e.Log
-	e.process.RestartDelay = time.Duration(e.RestartDelay)
 	e.process.ReadStdoutFn = e.outputReader
 	e.process.ReadStderrFn = e.cmdReadErr
+	e.process.RestartDelay = time.Duration(e.RestartDelay)
+	e.process.StopOnError = e.StopOnError
+	e.process.Log = e.Log
 
 	if err = e.process.Start(); err != nil {
 		// if there was only one argument, and it contained spaces, warn the user

plugins/inputs/execd/execd_test.go

@@ -50,7 +50,7 @@ func TestExternalInputWorks(t *testing.T) {
 	require.NoError(t, err)
 
 	e := &Execd{
-		Command:      []string{exe, "-counter"},
+		Command:      []string{exe, "-mode", "counter"},
 		Environment:  []string{"PLUGINS_INPUTS_EXECD_MODE=application", "METRIC_NAME=counter"},
 		RestartDelay: config.Duration(5 * time.Second),
 		Signal:       "STDIN",
@@ -158,6 +158,62 @@ test{handler="execd",quantile="0.5"} 42.0
 	testutil.RequireMetricsEqual(t, expected, actual, testutil.IgnoreTime())
 }
 
+func TestStopOnError(t *testing.T) {
+	exe, err := os.Executable()
+	require.NoError(t, err)
+
+	plugin := &Execd{
+		Command:      []string{exe, "-mode", "fail"},
+		Environment:  []string{"PLUGINS_INPUTS_EXECD_MODE=application"},
+		StopOnError:  true,
+		RestartDelay: config.Duration(5 * time.Second),
+		Log:          testutil.Logger{},
+	}
+
+	parser := models.NewRunningParser(&influx.Parser{}, &models.ParserConfig{})
+	require.NoError(t, parser.Init())
+	plugin.SetParser(parser)
+
+	var acc testutil.Accumulator
+	require.NoError(t, plugin.Start(&acc))
+	defer plugin.Stop()
+
+	require.Eventually(t, func() bool {
+		_, running := plugin.process.State()
+		return !running
+	}, 3*time.Second, 100*time.Millisecond)
+
+	state, running := plugin.process.State()
+	require.False(t, running)
+	require.Equal(t, 42, state.ExitCode())
+}
+
+func TestStopOnErrorSuccess(t *testing.T) {
+	exe, err := os.Executable()
+	require.NoError(t, err)
+
+	plugin := &Execd{
+		Command:      []string{exe, "-mode", "success"},
+		Environment:  []string{"PLUGINS_INPUTS_EXECD_MODE=application"},
+		StopOnError:  true,
+		RestartDelay: config.Duration(100 * time.Millisecond),
+		Log:          testutil.Logger{},
+	}
+
+	parser := models.NewRunningParser(&influx.Parser{}, &models.ParserConfig{})
+	require.NoError(t, parser.Init())
+	plugin.SetParser(parser)
+
+	var acc testutil.Accumulator
+	require.NoError(t, plugin.Start(&acc))
+	defer plugin.Stop()
+
+	// Wait for at least two metric as this indicates the process was restarted
+	require.Eventually(t, func() bool {
+		return acc.NMetrics() > 1
+	}, 3*time.Second, 100*time.Millisecond)
+}
+
 func readChanWithTimeout(t *testing.T, metrics chan telegraf.Metric, timeout time.Duration) telegraf.Metric {
 	to := time.NewTimer(timeout)
 	defer to.Stop()
@@ -188,20 +244,32 @@ func (tm *TestMetricMaker) Log() telegraf.Logger {
 	return models.NewLogger("TestPlugin", "test", "")
 }
 
-var counter = flag.Bool("counter", false,
-	"if true, act like line input program instead of test")
-
 func TestMain(m *testing.M) {
+	var mode string
+
+	flag.StringVar(&mode, "mode", "counter", "determines the output when run as mockup program")
 	flag.Parse()
-	runMode := os.Getenv("PLUGINS_INPUTS_EXECD_MODE")
-	if *counter && runMode == "application" {
+
+	operationMode := os.Getenv("PLUGINS_INPUTS_EXECD_MODE")
+	if operationMode != "application" {
+		// Run the normal test mode
+		os.Exit(m.Run())
+	}
+
+	// Run as a mock program
+	switch mode {
+	case "counter":
 		if err := runCounterProgram(); err != nil {
 			os.Exit(1)
 		}
 		os.Exit(0)
+	case "fail":
+		os.Exit(42)
+	case "success":
+		fmt.Println("test value=42i")
+		os.Exit(0)
 	}
-	code := m.Run()
-	os.Exit(code)
+	os.Exit(23)
 }
 
 func runCounterProgram() error {
@@ -216,9 +284,7 @@ func runCounterProgram() error {
 	for scanner.Scan() {
 		m := metric.New(envMetricName,
 			map[string]string{},
-			map[string]interface{}{
-				"count": i,
-			},
+			map[string]interface{}{"count": i},
 			time.Now(),
 		)
 		i++

plugins/inputs/execd/sample.conf

@@ -18,17 +18,21 @@
   ##   "SIGHUP"  : Send a HUP signal. Not available on Windows. (not recommended)
   ##   "SIGUSR1" : Send a USR1 signal. Not available on Windows.
   ##   "SIGUSR2" : Send a USR2 signal. Not available on Windows.
-  signal = "none"
+  # signal = "none"
 
   ## Delay before the process is restarted after an unexpected termination
-  restart_delay = "10s"
+  # restart_delay = "10s"
 
   ## Buffer size used to read from the command output stream
   ## Optional parameter. Default is 64 Kib, minimum is 16 bytes
   # buffer_size = "64Kib"
 
+  ## Disable automatic restart of the program and stop if the program exits
+  ## with an error (i.e. non-zero error code)
+  # stop_on_error = false
+
   ## Data format to consume.
   ## Each data format has its own unique set of configuration options, read
   ## more about them here:
   ## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_INPUT.md
-  data_format = "influx"
+  # data_format = "influx"