From 4ecbc7caae1726f0eb4646aa0bd94947eed86f90 Mon Sep 17 00:00:00 2001
From: Matthew Heon <matthew.heon@pm.me>
Date: Tue, 21 Sep 2021 14:24:23 -0400
Subject: Add a backoff and retries to retrieving exited event

There's a potential race around extremely short-running
containers and events with journald. Events may not be written
for some time (small, but appreciable) after they are received,
and as such we can fail to retrieve it if there is a sufficiently
short time between us writing the event and trying to read it.

Work around this by just retrying, with a 0.25 second delay
between retries, up to 4 times.

[NO TESTS NEEDED] because I have no idea how to reproduce this
race in CI.

Fixes #11633

Signed-off-by: Matthew Heon <matthew.heon@pm.me>
---
 pkg/domain/infra/abi/containers.go | 55 +++++++++++++++++---------------------
 1 file changed, 25 insertions(+), 30 deletions(-)

diff --git a/pkg/domain/infra/abi/containers.go b/pkg/domain/infra/abi/containers.go
index dc5f7a0df..affed64d1 100644
--- a/pkg/domain/infra/abi/containers.go
+++ b/pkg/domain/infra/abi/containers.go
@@ -830,21 +830,7 @@ func (ic *ContainerEngine) ContainerStart(ctx context.Context, namesOrIds []stri
 				}
 				return reports, errors.Wrapf(err, "unable to start container %s", ctr.ID())
 			}
-
-			if ecode, err := ctr.Wait(ctx); err != nil {
-				if errors.Cause(err) == define.ErrNoSuchCtr {
-					// Check events
-					event, err := ic.Libpod.GetLastContainerEvent(ctx, ctr.ID(), events.Exited)
-					if err != nil {
-						logrus.Errorf("Cannot get exit code: %v", err)
-						exitCode = define.ExecErrorCodeNotFound
-					} else {
-						exitCode = event.ContainerExitCode
-					}
-				}
-			} else {
-				exitCode = int(ecode)
-			}
+			exitCode = ic.GetContainerExitCode(ctx, ctr)
 			reports = append(reports, &entities.ContainerStartReport{
 				Id:       ctr.ID(),
 				RawInput: rawInput,
@@ -985,21 +971,7 @@ func (ic *ContainerEngine) ContainerRun(ctx context.Context, opts entities.Conta
 		report.ExitCode = define.ExitCode(err)
 		return &report, err
 	}
-
-	if ecode, err := ctr.Wait(ctx); err != nil {
-		if errors.Cause(err) == define.ErrNoSuchCtr {
-			// Check events
-			event, err := ic.Libpod.GetLastContainerEvent(ctx, ctr.ID(), events.Exited)
-			if err != nil {
-				logrus.Errorf("Cannot get exit code: %v", err)
-				report.ExitCode = define.ExecErrorCodeNotFound
-			} else {
-				report.ExitCode = event.ContainerExitCode
-			}
-		}
-	} else {
-		report.ExitCode = int(ecode)
-	}
+	report.ExitCode = ic.GetContainerExitCode(ctx, ctr)
 	if opts.Rm && !ctr.ShouldRestart(ctx) {
 		if err := ic.Libpod.RemoveContainer(ctx, ctr, false, true); err != nil {
 			if errors.Cause(err) == define.ErrNoSuchCtr ||
@@ -1013,6 +985,29 @@ func (ic *ContainerEngine) ContainerRun(ctx context.Context, opts entities.Conta
 	return &report, nil
 }
 
+func (ic *ContainerEngine) GetContainerExitCode(ctx context.Context, ctr *libpod.Container) int {
+	exitCode, err := ctr.Wait(ctx)
+	if err == nil {
+		return int(exitCode)
+	}
+	if errors.Cause(err) != define.ErrNoSuchCtr {
+		logrus.Errorf("Could not retrieve exit code: %v", err)
+		return define.ExecErrorCodeNotFound
+	}
+	// Make 4 attempt with 0.25s backoff between each for 1 second total
+	var event *events.Event
+	for i := 0; i < 4; i++ {
+		event, err = ic.Libpod.GetLastContainerEvent(ctx, ctr.ID(), events.Exited)
+		if err != nil {
+			time.Sleep(250 * time.Millisecond)
+			continue
+		}
+		return int(event.ContainerExitCode)
+	}
+	logrus.Errorf("Could not retrieve exit code from event: %v", err)
+	return define.ExecErrorCodeNotFound
+}
+
 func (ic *ContainerEngine) ContainerLogs(ctx context.Context, containers []string, options entities.ContainerLogsOptions) error {
 	if options.StdoutWriter == nil && options.StderrWriter == nil {
 		return errors.New("no io.Writer set for container logs")
-- 
cgit v1.2.3-54-g00ecf