I am trying to migrate from hudson to jenkins. My intention was to keep the hudson server up and start jenkins on a new port and manually create jobs on the jenkins. However, when I install jenkins using sudo apt-get install jenkins, hudson is uninstalled.
Is there a way to keep both running?
I tried to install hudson using sudo apt-get install hudson after jenkins removed it; in an attempt to keep both running. But installing hudson also removes jenkins and I am back to square 1.
The two Debian packages are marked as conflicting with each other; that's why installing one removes the other.
What you could do is to download the regular Jenkins WAR file and start that manually, specifying the new port, e.g.:
java -jar jenkins.war --httpPort=9090
But be wary that Hudson saves its config by default probably in /var/lib/hudson and Jenkins, in an attempt to help you migrate seamlessly, will likely auto-detect your existing Hudson config and use that.
So starting Jenkins will probably show your existing Hudson config, and any changes you make in the Jenkins UI may adversely affect your running Hudson install. So you probably want to force Jenkins to use a different config directory to keep the two servers completely separated.
You can do this by specifying a JENKINS_HOME environment variable containing the path you want to use.