Delay the restart of application when a status report of failure is g…

…iven (#25339)

* Delay the restart of application when a status report of failure is given.

* Add changelog.

* Fix test and make it configurable.

* Run mage check

(cherry picked from commit 371871e)

x-pack/elastic-agent/CHANGELOG.next.asciidoc

@@ -56,8 +56,10 @@
 - Fixed: limit for retries to Kibana configurable {issue}25063[25063]
 - Fix issue with status and inspect inside of container {pull}25204[25204]
 - Remove FLEET_SERVER_POLICY_NAME env variable as it was not used {pull}25149[25149]
+- Reduce log level for listener cleanup to debug {pull}25274
 - Passing in policy id to container command works {pull}25352[25352]
 - Reduce log level for listener cleanup to debug {pull}25274[25274]
+- Delay the restart of application when a status report of failure is given {pull}25339[25339]
 
 ==== New features
 

x-pack/elastic-agent/pkg/agent/cmd/enroll_cmd.go

@@ -612,13 +612,6 @@ func waitForFleetServer(ctx context.Context, agentSubproc <-chan *os.ProcessStat
 				}
 				resChan <- waitResult{enrollmentToken: token}
 				break
-			} else if app.Status == proto.Status_FAILED {
-				// app completely failed; exit now
-				if app.Message != "" {
-					log.Infof("Fleet Server - %s", app.Message)
-				}
-				resChan <- waitResult{err: errors.New(app.Message)}
-				break
 			}
 			if app.Message != "" {
 				appMsg := fmt.Sprintf("Fleet Server - %s", app.Message)

x-pack/elastic-agent/pkg/agent/operation/common_test.go

@@ -41,7 +41,9 @@ func getTestOperator(t *testing.T, downloadPath string, installPath string, p *a
 			Delay:        3 * time.Second,
 			MaxDelay:     10 * time.Second,
 		},
-		ProcessConfig: &process.Config{},
+		ProcessConfig: &process.Config{
+			FailureTimeout: 1, // restart instantly
+		},
 		DownloadConfig: &artifact.Config{
 			TargetDirectory: downloadPath,
 			InstallPath:     installPath,

x-pack/elastic-agent/pkg/core/plugin/process/app.go

@@ -58,7 +58,9 @@ type Application struct {
 
 	logger *logger.Logger
 
-	appLock sync.Mutex
+	appLock          sync.Mutex
+	restartCanceller context.CancelFunc
+	restartConfig    map[string]interface{}
 }
 
 // ArgsDecorator decorates arguments before calling an application

x-pack/elastic-agent/pkg/core/plugin/process/status.go

@@ -5,7 +5,9 @@
 package process
 
 import (
+	"context"
 	"fmt"
+	"time"
 
 	"gopkg.in/yaml.v2"
 
@@ -35,21 +37,74 @@ func (a *Application) OnStatusChange(s *server.ApplicationState, status proto.St
 			return
 		}
 
-		// kill the process
-		if a.state.ProcessInfo != nil {
-			_ = a.state.ProcessInfo.Process.Kill()
-			a.state.ProcessInfo = nil
-		}
-		ctx := a.startContext
-		tag := a.tag
-
 		// it was marshalled to pass into the state, so unmarshall will always succeed
 		var cfg map[string]interface{}
 		_ = yaml.Unmarshal([]byte(s.Config()), &cfg)
 
-		err := a.start(ctx, tag, cfg)
-		if err != nil {
-			a.setState(state.Crashed, fmt.Sprintf("failed to restart: %s", err), nil)
+		// start the failed timer
+		a.startFailedTimer(cfg)
+	} else {
+		a.stopFailedTimer()
+	}
+}
+
+// startFailedTimer starts a timer that will restart the application if it doesn't exit failed after a period of time.
+//
+// This does not grab the appLock, that must be managed by the caller.
+func (a *Application) startFailedTimer(cfg map[string]interface{}) {
+	if a.restartCanceller != nil {
+		// already have running failed timer; just update config
+		a.restartConfig = cfg
+		return
+	}
+
+	ctx, cancel := context.WithCancel(a.startContext)
+	a.restartCanceller = cancel
+	a.restartConfig = cfg
+	t := time.NewTimer(a.processConfig.FailureTimeout)
+	go func() {
+		defer func() {
+			a.appLock.Lock()
+			a.restartCanceller = nil
+			a.restartConfig = nil
+			a.appLock.Unlock()
+		}()
+
+		select {
+		case <-ctx.Done():
+			return
+		case <-t.C:
+			a.restart(a.restartConfig)
 		}
+	}()
+}
+
+// stopFailedTimer stops the timer that would restart the application from reporting failure.
+//
+// This does not grab the appLock, that must be managed by the caller.
+func (a *Application) stopFailedTimer() {
+	if a.restartCanceller == nil {
+		return
+	}
+	a.restartCanceller()
+	a.restartCanceller = nil
+}
+
+// restart restarts the application
+func (a *Application) restart(cfg map[string]interface{}) {
+	a.appLock.Lock()
+	defer a.appLock.Unlock()
+
+	// kill the process
+	if a.state.ProcessInfo != nil {
+		_ = a.state.ProcessInfo.Process.Kill()
+		a.state.ProcessInfo = nil
+	}
+	ctx := a.startContext
+	tag := a.tag
+
+	err := a.start(ctx, tag, cfg)
+	if err != nil {
+		a.setState(state.Crashed, fmt.Sprintf("failed to restart: %s", err), nil)
 	}
 }

x-pack/elastic-agent/pkg/core/process/config.go

@@ -8,16 +8,18 @@ import "time"
 
 // Config for fine tuning new process
 type Config struct {
-	SpawnTimeout time.Duration `yaml:"spawn_timeout" config:"spawn_timeout"`
-	StopTimeout  time.Duration `yaml:"stop_timeout" config:"stop_timeout"`
+	SpawnTimeout   time.Duration `yaml:"spawn_timeout" config:"spawn_timeout"`
+	StopTimeout    time.Duration `yaml:"stop_timeout" config:"stop_timeout"`
+	FailureTimeout time.Duration `yaml:"failure_timeout" config:"failure_timeout"`
 
 	// TODO: cgroups and namespaces
 }
 
 // DefaultConfig creates a config with pre-set default values.
 func DefaultConfig() *Config {
 	return &Config{
-		SpawnTimeout: 30 * time.Second,
-		StopTimeout:  30 * time.Second,
+		SpawnTimeout:   30 * time.Second,
+		StopTimeout:    30 * time.Second,
+		FailureTimeout: 10 * time.Second,
 	}
 }