Canonical Jenkins upgrade procedure:
- Stop the server.
- Tar up its whole directory Just In Case.
- Upgrade the server.
- Upgrade all the plugins, even ones saying they may asplode because what choice do you have really?
- Start the server.
- [solve the Halting Problem to determine whether everything still more or less works]
- If nothing breaks within the week, call it good.
- If something breaks after a week, blame it on a random developer. Face it, you’re not going to roll it back, are you?