Run a background process permanently on a node through a script on Jenkins and let Jenkins build successfully

Question

I am running a background process through a script , this script is invoked when Jenkin starts building. However, the jenkins build gets stuck and on looking at the console

Answer 1

There is a trick you can do in order you free a Jenkins thread.

What you can do is to execute a bash script through a ssh connection and send it to the background while saving the pid of the process somewhere so you can make checks further.

The format of the command would be:

ssh -n _hostname_ "_commands_ & echo \$! > \"_path_to_pid_file_\"" &

Example with a never-ending program:

ssh -n myhost.domain.com "tail -f /var/log/my.log & echo \$! > \"$WORKSPACE/pid\"" &

This example will spawn the tail process listening forever for new changes in the /var/log/my.log file and store its pid in the $WORKSPACE/pid file.

When executed from a Jenkins job the ssh process will exit immediately while the commands sent to the background will remain in execution in the specified host.

I do this in order to maintain always one of the services I run in my build farm in-sync with the latest code modification of it in the repository. Just have a job that ssh' into the target machine and then kill the process, update the service and re-launches it.

This could be a bit cumbersome but it works great!