Hi!
I am using Jenkins in Docker and I map a folder from local machine to the container's /var/jenkins_home to preserve JENKINS_HOME.
There are two things I am wondering about, and maybe you can comment:
1. Can new Jenkins corrupt existing JENKINS_HOME?
Let's assume I have Jenkins in version X running, I want to upgrade so I have built new image, with Jenkins version Y, same plugins - maybe updated during the image build
Is it possible that when I restart Jenkins with new image with version Y, the existing JENKINS_HOME won't be compatible with new version?
Is it possible that after restart JENKINS_HOME will be changed in a way that it won't be possible to use it again with version X - if I want to rollback for whatever reason?
2. What happens when two instances share JENKINS_HOME?
I want to have a simple test environment - let's not discuss now if it's a good or bad approach :) - so next to a working Jenkins container I start another one in a quiet mode (no job will start), with a new image I want to try out
The first idea is to copy original JENKINS_HOME and use this copy, but what if the home is very big and I do not have much space - how bad would running second Jenkins with JENKINS_HOME mapped to the same folder on a local host would be? (I haven't considered that option, but I was asked 'why')
I know I can just run it and check, but I think there might be plenty of different cases that I will not see in my simple test, but maybe some of you have more experience or ran into issues before
BR
Ewelina