Docker Image: new Exit and Restart Behavior for Controllers

Jenkins previously restarted itself after upgrading plugins or via the /restart or /safeRestart endpoints by calling exec(2). This was fragile and exposed users to a variety of bugs.

The ExitLifecycle implementation allows the main process to exit normally before starting it again from scratch, relying on the exit code to signal to the container orchestrator that the container ought to be restarted rather than to remain shut down.

Avoiding exec(2) from Java code, with all the associated complexity of closing file handles and making low-level system calls via JNA, eliminates exposure to a category of bugs.

You can read more about this on the following issues: jenkinsci/jenkins#5899 and jenkinsci/docker#1268.

Since the Jenkins Weekly 2.344 and the Jenkins LTS 2.332.3, the Docker image for Jenkins controller uses the new lifecycle ExitLifecycle by default.

It means that when the Jenkins controller triggers any "restart" or "exit" event, then its container exits.

If you are running Jenkins in a controller as a container, you should add a "container restart policy" different than none to ensure that the container is restarted automatically.

If you are running Jenkins in production in a container, chances are great that you already have a restart policy set and the change will be transparent. But we updated the jenkinsci/docker documentation to mention that the flag --restart=on-failure is set when starting a Jenkins controller container.

If you do not have a container restart policy defined, please find the different following methods depending on your container orchestrator: