commit def549c8f6 passed through the context
to the daemon.ContainerStart function. As a result, restarting containers
no longer is an atomic operation, because a context cancellation could
interrupt the restart (between "stopping" and "(re)starting"), resulting
in the container being stopped, but not restarted.
Restarting a container, or more factually; making a successful request on
the `/containers/{id]/restart` endpoint, should be an atomic operation.
This patch uses a context.WithoutCancel for restart requests.
It's worth noting that daemon.containerStop already uses context.WithoutCancel,
so in that function, we'll be wrapping the context twice, but this should
likely not cause issues (just redundant for this code-path).
Before this patch, starting a container that bind-mounts the docker socket,
then restarting itself from within the container would cancel the restart
operation. The container would be stopped, but not started after that:
docker run -dit --name myself -v /var/run/docker.sock:/var/run/docker.sock docker:cli sh
docker exec myself sh -c 'docker restart myself'
docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
3a2a741c65ff docker:cli "docker-entrypoint.s…" 26 seconds ago Exited (128) 7 seconds ago myself
With this patch: the stop still cancels the exec, but does not cancel the
restart operation, and the container is started again:
docker run -dit --name myself -v /var/run/docker.sock:/var/run/docker.sock docker:cli sh
docker exec myself sh -c 'docker restart myself'
docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
4393a01f7c75 docker:cli "docker-entrypoint.s…" About a minute ago Up 4 seconds myself
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
aeb8972281