Document skipping initial setup wizard

[ringerc]

Documented steps to skip setup wizard didn't appear to work on jenkins/jenkins:latest or jenkins/jenkins:latest. Neither did variants of them that tried to cope with volume-mounting etc, like:

RUN echo $JENKINS_VERSION | tee \
    /usr/share/jenkins/ref/jenkins.install.UpgradeWizard.state \
    /usr/share/jenkins/ref/jenkins.install.InstallUtil.lastExecVersion

Instead, recommend use of a system property that is known to work.

[daniel-beck]

Documented steps

FWIW the "documented" (in this repo only) steps have always been an unsupported hack and I don't understand how they became preferable over the intended method. Perhaps because it didn't require changing how to invoke docker? Understanding of how this happened may help with documenting the supported method.

---

Re-reading the discussion in JENKINS-40279 makes apparent that many users involved do not properly distinguish between the setup wizard and the upgrade wizard.

• Setup: First launch only (except in rare circumstances like a mostly pristine Jenkins home directory). Installs plugins from a selection and creates initial admin user.
• Upgrade: When crossing a version boundary on upgrade that introduces new recommended plugins. I don't think this has happened since the release 2.0 from early 2016 (or 2.7.x for LTS).

Perhaps that could explain part of this? The system property does not help with the latter?

[NorseGaud]

None of the proposed methods work with the latest LTS (2.277.1)

[slide]

@NorseGaud Are you referring to 2.277.1?

[NorseGaud]

@slide Yep -- it seems like JAVA_OPTS="-Djenkins.install.runSetupWizard=false" when launching lts tag from docker has no impact and the admin password wizard/login still shows. Maybe I'm misunderstanding.