Merge pull request #63160 from sjenning/no-waitlogs-stopped-pod

Automatic merge from submit-queue (batch tested with PRs 63252, 63160). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>. kubelet: logs: do not wait when following terminated container Currently, a `kubectl logs -f` on a terminated container will output the logs, wait 5 seconds (`stateCheckPeriod`), then return. The 5 seconds delay should not occur as the container is terminated and unable to generate additional log messages. This PR puts a check at the beginning of `waitLogs()` to avoid doing the wait when the container is not running. @derekwaynecarr @smarterclayton

Merge pull request #63160 from sjenning/no-waitlogs-stopped-pod
284e8182 · Kubernetes Submit Queue · GitHub · e01858c5 · 5da3a1d5 · 284e8182
Unverified Commit 284e8182 authored Apr 27, 2018 by Kubernetes Submit Queue Committed by GitHub Apr 27, 2018
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Showing with 20 additions and 9 deletions

logs.go pkg/kubelet/kuberuntime/logs/logs.go +20 -9

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--- a/pkg/kubelet/kuberuntime/logs/logs.go
+++ b/pkg/kubelet/kuberuntime/logs/logs.go
@@ -354,9 +354,28 @@ func ReadLogs(path, containerID string, opts *LogOptions, runtimeService interna
 	}
 }

+func isContainerRunning(id string, r internalapi.RuntimeService) (bool, error) {
+	s, err := r.ContainerStatus(id)
+	if err != nil {
+		return false, err
+	}
+	// Only keep following container log when it is running.
+	if s.State != runtimeapi.ContainerState_CONTAINER_RUNNING {
+		glog.V(5).Infof("Container %q is not running (state=%q)", id, s.State)
+		// Do not return error because it's normal that the container stops
+		// during waiting.
+		return false, nil
+	}
+	return true, nil
+}
+
 // waitLogs wait for the next log write. It returns a boolean and an error. The boolean
 // indicates whether a new log is found; the error is error happens during waiting new logs.
 func waitLogs(id string, w *fsnotify.Watcher, runtimeService internalapi.RuntimeService) (bool, error) {
+	// no need to wait if the pod is not running
+	if running, err := isContainerRunning(id, runtimeService); !running {
+		return false, err
+	}
 	errRetry := 5
 	for {
 		select {
@@ -374,17 +393,9 @@ func waitLogs(id string, w *fsnotify.Watcher, runtimeService internalapi.Runtime
 			}
 			errRetry--
 		case <-time.After(stateCheckPeriod):
-			s, err := runtimeService.ContainerStatus(id)
-			if err != nil {
+			if running, err := isContainerRunning(id, runtimeService); !running {
 				return false, err
 			}
-			// Only keep following container log when it is running.
-			if s.State != runtimeapi.ContainerState_CONTAINER_RUNNING {
-				glog.V(5).Infof("Container %q is not running (state=%q)", id, s.State)
-				// Do not return error because it's normal that the container stops
-				// during waiting.
-				return false, nil
-			}
 		}
 	}
 }