Stop following logs using timers

This incorporates code from PR #6591 and #6614 but does not use
event channels to detect container state and rather uses timers
with a defined wait duration before calling t.StopAtEOF() to
ensure the last log entry is output before a container exits.

The polling interval is set to 250 milliseconds based on polling
interval defined in hpcloud/tail here:
https://github.com/hpcloud/tail/blob/v1.0.0/watch/polling.go#L117

Co-authored-by: Qi Wang <qiwan@redhat.com>
Signed-off-by: jgallucci32 <john.gallucci.iv@gmail.com>

2 files changed, 42 insertions, 0 deletions

diff --git a/libpod/container_log.go b/libpod/container_log.go
index 071882bc2..9a2f8aa2f 100644
--- a/libpod/container_log.go
+++ b/libpod/container_log.go
@@ -1,7 +1,9 @@
 package libpod
 
 import (
+	"fmt"
 	"os"
+	"time"
 
 	"github.com/containers/libpod/libpod/define"
 	"github.com/containers/libpod/libpod/logs"
@@ -81,5 +83,33 @@ func (c *Container) readFromLogFile(options *logs.LogOptions, logChannel chan *l
 		}
 		options.WaitGroup.Done()
 	}()
+	// Check if container is still running or paused
+	if options.Follow {
+		go func() {
+			for {
+				state, err := c.State()
+				if err != nil {
+					time.Sleep(250 * time.Millisecond)
+					tailError := t.StopAtEOF()
+					if tailError != nil && fmt.Sprintf("%v", tailError) != "tail: stop at eof" {
+						logrus.Error(tailError)
+					}
+					if errors.Cause(err) != define.ErrNoSuchCtr {
+						logrus.Error(err)
+					}
+					break
+				}
+				if state != define.ContainerStateRunning && state != define.ContainerStatePaused {
+					time.Sleep(250 * time.Millisecond)
+					tailError := t.StopAtEOF()
+					if tailError != nil && fmt.Sprintf("%v", tailError) != "tail: stop at eof" {
+						logrus.Error(tailError)
+					}
+					break
+				}
+				time.Sleep(250 * time.Millisecond)
+			}
+		}()
+	}
 	return nil
 }
diff --git a/test/e2e/logs_test.go b/test/e2e/logs_test.go
index a4a59acb2..fc0739d3d 100644
--- a/test/e2e/logs_test.go
+++ b/test/e2e/logs_test.go
@@ -311,4 +311,16 @@ var _ = Describe("Podman logs", func() {
 		logs.WaitWithDefaultTimeout()
 		Expect(logs).To(Not(Exit(0)))
 	})
+
+	It("follow output stopped container", func() {
+		containerName := "logs-f"
+
+		logc := podmanTest.Podman([]string{"run", "--name", containerName, "-d", ALPINE})
+		logc.WaitWithDefaultTimeout()
+		Expect(logc).To(Exit(0))
+
+		results := podmanTest.Podman([]string{"logs", "-f", containerName})
+		results.WaitWithDefaultTimeout()
+		Expect(results).To(Exit(0))
+	})
 })