Git, Gerrit and Jenkins Code Review and Automated Build Alex Blewitt @alblue SkillsMatter October 2011

Git • Matthew has talked about Git extensively • Ask @matthewmccull for more details :) • Alternatively look for Git Tip of the Week • #gtotw • alblue.bandlem.com/search/label/gtotw

Gerrit • Git-backed review system • Used by Eclipse, Android • Acts as a front-end to a central Git repo • When review complete, auto-merged

Jenkins/Hudson • Automated build platform • Can be used with/without Gerrit/Git • Has triggers to hook into events • Hudson donated to Eclipse Foundation • Jenkins donated to SPI

Problem Why are we here again?

Team development • Work as a team • Merge to centralised repository • Review all code changes ✓But without affecting others

Attempt I • Review before commit ✓No cruft in repository ✓Doesn’t affect others ✴No guarantee reviewed == commited

Attempt II • Review after commit ✓Guarantee reviewed == commited ✴Cruft in repository ✴May affect others

Attempt III • Review after commit on unique branch ✓Guarantee reviewed == commited ✓No cruft in repository on main branch ✓Will not affect others

Pushing • Pushing to Gerrit creates a new branch • master:refs/for/master • Review comments can be added to files • Can compare before/after changes • Change-Id allows patch sets per branch

Automated checks Does the change compile and test?

Checking it out • Jenkins can be told when a change occurs • Can automatically compile and test code • Can generate test report • Can mark success/failure in Gerrit

Jenkins Gerrit Trigger • Can install the Gerrit Trigger Plugin • Automatically installs Git plugin • Set refspect to pull as $GERRIT_REFSPEC • Build Trigger as Gerrit Event • Project must match project(s) • Project Path ** Branch Path **

Gerrit workflow

Demo Putting it all together

Permissions • Gerrit can act as a permissioned keeper • Merges • Push-to-branch directly (skip review) • Clone/fetching • Review/Submit

Commit Hooks • Can be configured to auto add Change-Id • Git • scp -P 29418 gerrit:/hooks/commit-msg • EGit • git config gerrit.createchangeid true

Merging • Can configure merge options per-project • Fast Forward Only • Merge If necessary • Always Merge • Cherry Pick

Review Notes • Gerrit 2.2+ stores more info in Git repos • Permissions are stored refs/meta/config • Inherited from All-Projects.git • Review data encoded in Git Notes • refs/notes/review • git log --show-notes=*

Future • Currently (2.2) a SQL DB is still required • SSH keys, user information • Project metadata • More info is moving to Git repositories • Review notes • Configuration

Git, Gerrit and Jenkins Code Review and Automated Build Alex Blewitt @alblue SkillsMatter October 2011