Ensure that exec sends resize events

We previously tried to send resize events only after the exec
session successfully started, which makes sense (we might drop an
event or two that came in before the exec session started
otherwise). However, the start function blocks, so waiting
actually means we send no resize events at all, which is
obviously worse than losing a few.. Sending resizes before attach
starts seems to work fine in my testing, so let's do that until we
get bug reports that it doesn't work.

Fixes #5584

Signed-off-by: Matthew Heon <mheon@redhat.com>

2 files changed, 6 insertions, 5 deletions

diff --git a/libpod/container_exec.go b/libpod/container_exec.go
index 7ed7a3343..6b88e5205 100644
--- a/libpod/container_exec.go
+++ b/libpod/container_exec.go
@@ -575,7 +575,7 @@ func (c *Container) ExecResize(sessionID string, newSize remotecommand.TerminalS
 		return errors.Wrapf(define.ErrNoSuchExecSession, "container %s has no exec session with ID %s", c.ID(), sessionID)
 	}
 
-	logrus.Infof("Removing container %s exec session %s", c.ID(), session.ID())
+	logrus.Infof("Resizing container %s exec session %s to %+v", c.ID(), session.ID(), newSize)
 
 	if session.State != define.ExecStateRunning {
 		return errors.Wrapf(define.ErrExecSessionStateInvalid, "cannot resize container %s exec session %s as it is not running", c.ID(), session.ID())
@@ -592,9 +592,6 @@ func (c *Container) Exec(config *ExecConfig, streams *AttachStreams, resize <-ch
 	if err != nil {
 		return -1, err
 	}
-	if err := c.ExecStartAndAttach(sessionID, streams); err != nil {
-		return -1, err
-	}
 
 	// Start resizing if we have a resize channel.
 	// This goroutine may likely leak, given that we cannot close it here.
@@ -605,6 +602,7 @@ func (c *Container) Exec(config *ExecConfig, streams *AttachStreams, resize <-ch
 	// session.
 	if resize != nil {
 		go func() {
+			logrus.Debugf("Sending resize events to exec session %s", sessionID)
 			for resizeRequest := range resize {
 				if err := c.ExecResize(sessionID, resizeRequest); err != nil {
 					// Assume the exec session went down.
@@ -615,6 +613,10 @@ func (c *Container) Exec(config *ExecConfig, streams *AttachStreams, resize <-ch
 		}()
 	}
 
+	if err := c.ExecStartAndAttach(sessionID, streams); err != nil {
+		return -1, err
+	}
+
 	session, err := c.ExecSession(sessionID)
 	if err != nil {
 		return -1, err
diff --git a/libpod/oci_conmon_linux.go b/libpod/oci_conmon_linux.go
index 82c5d7020..6d9a976cb 100644
--- a/libpod/oci_conmon_linux.go
+++ b/libpod/oci_conmon_linux.go
@@ -793,7 +793,6 @@ func (r *ConmonOCIRuntime) ExecAttachResize(ctr *Container, sessionID string, ne
 	}
 	defer controlFile.Close()
 
-	logrus.Debugf("Received a resize event for container %s exec session %s: %+v", ctr.ID(), sessionID, newSize)
 	if _, err = fmt.Fprintf(controlFile, "%d %d %d\n", 1, newSize.Height, newSize.Width); err != nil {
 		return errors.Wrapf(err, "failed to write to ctl file to resize terminal")
 	}