Clean way of launching a shell script in background from Jenkins

Question

What's the proper way to launch a script from jenkins, don't get the build hanging, and leave the process running? I can't seem to get it to work. Either the script doesn't run or the build hangs.

If I put in the build's "Execute shell" step bash relaunch.sh & or relaunch.sh > output.log & or nohup bash relaunch.sh &, nothing happens; build finishes, but the process doesn't run. I guess it can be related to Jenkins waiting for the error pipe to close.

If I do nohup bash relaunch.sh 2>&1 > output.log as suggested here, the output is properly redirected, but the build hangs (doesn't finish), and the process dies when I kill the build.

Adding export BUILD_ID=dontKillMe, as suggested here, here, and here, either to the "Execute shell" step or the script itself doesn't help either. The build hangs and the process dies when I kill the build. Needless to say, my knowledge of linux is very limited.

How do people do this in a clean way?

Answer 1

A convenient way to achieve that is to change the environment variable BUILD_ID under Execute shell which Jenkins's ProcessTreeKiller is looking for.

By doing,

BUILD_ID=dontKillMe nohup bash relaunch.sh & 

Jenkins will assume that the background job is not spawned by the build and will not kill them after finishing the job.

Thanks to Joshua for his observation that you could also use JENKINS_NODE_COOKIE as

JENKINS_NODE_COOKIE=dontKillMe