Gerrit Code Review with GitHub plugin

Luca@gerritforge.com
http://www.gerritforge.com
Twitter: @gitenterprise
GitHub plugin for …
Luca Milanesio
GerritForge
gerritGerrit Code Review
Platinum Sponsor

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About Luca
• Luca Milanesio
Co-founder of GerritForge
• over 20 years of experience
in Agile Development
SCM and ALM worldwide
• Contributor to Jenkins
since 2007 (and previously Hudson)
• Git SCM mentor
for the Enterprise since 2009
• Contributor to Gerrit Code Review community since 2011

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About GerritForge
Founded in 2009 in London UK
Mission: Agile Enterprise
Products:

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Agenda
 Fork+Pull request or Change review ?
 People says …
 My experience say …
 Plugging two worlds together
 echo "github" | sed -e "s/git/gerrit/"
 Pull requests and Repo replication
 What do YOU think ?

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Two divided review worlds
BRANCH
+
PULL
REQUEST
CHECKOUT
+
AMEND

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Fork + Pull request
GitHub BitBucket GitLab Gitorious + others …
> 10M repositories > 4M users
SourceRepo
mastera1c 2df f9a
fork
masterdec 6fa 7a1

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Change review (rebase example)
Gerrit GitBlit
+ others?
SourceRepo
mastera1c 2df 7a1
dec 6fa 7a1 changes/27/1627/*
amend amend

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Two worlds at a glance
1. BRANCH
2. SCORE THE
BRANCH
3. MERGE ALL
COMMITs in
BRANCH
1. CHECKOUT
2. SCORE THE
COMMIT
3. MERGE ONLY the
REVIEWED
COMMIT

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There are two fundamental problems with single-
patch review systems:
1. They encourage lumping at-best-weakly-related
changes together.
2. They encourage you to hide your history.
[http://bit.ly/1hhQkcA]
The pull-request system looks like an incredible
easy way to contribute to any project hosted on
Github [but] doing any proper and useful
contribution to a software is never done right the
first time.
But as a software maintainer you'll end up with
pull-request you'll never get finished unless you
wrap things up yourself.
[http://bit.ly/1o7HIb6]
A big advantage in Github's favor is the number of
developers that are familiar with it compared to
Gerrit.
Gerrit can be popular with Git power-users, but
friction-free use of it requires intermediate or
advanced git knowledge, and tolerance of a steep
learning curve.
[http://bit.ly/1cJV8IJ]
I have no problem with people using github as a
hosting site, but in order for *me* to pull from
github, you need to
(a) make a real pull request […]: real explanation,
proper email addresses, proper shortlog, and
proper diffstat.
(b) since github identities are random, I expect
the pull request to be a signed tag
[http://bit.ly/1iONQ4L]

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MY OWN
(OpenSource +
Enterprise)
[humble]
EXPERIENCE …

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Review model
DO NOT make git bisect + git cherry-pick useless
DO NOT throw commits over the fence
(e.g. “I’ve made the pull request, now it’s up to you”)

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Governance
DEFINE rules for your project
TRUST your identities and roles

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Social engagement
MAKE your project visible
MAKE collaboration easy and fun

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Growth
PLAN for collaboration model to scale
AVOID explosion of forks and pending pull-requests

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Can we take both worlds ?
+ = ?

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GitHub plugin for Gerrit Code Review
https://gerrit-review.googlesource.com/#/admin/projects/plugins/github
1. Imports Pull Requests  Gerrit Changes / Topics
2. Reuses GitHub identity using Gerrit auth rules
3. Replication: keeps presence on http://github.com
4. Prevents explosion of unmanaged forks
5. Avoid GitHub spamming  one-email-per-change

18 .io
Gerrit and GitHub? Who is ever gonna use it?
June 2014 Statistics
select count(*) from accounts = 1664 users
select count(*) from changes = 3654 changes
select count(*) from patch_sets = 4720 patch-sets
find . -name '*.git' | wc –l = 5022 repositories
du -s -h git = 140 GBytes

19 .io
THIS IS COOL !
How can use it ?

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SPEEDY WAY
http://GerritHub.io/login

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DEMO TIME
[http://www.youtube.com/watch?v=jeWTvDad6VM]

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HACKY WAY
Build the plugin from source

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Step#1 - GitHub OAuth 2.0 application keys
https://github.com/settings/applications/new
Your server URL
(hostname / port Gerrit
will listen to)
OAuth 2.0 callback URL
is
Your server URL +
/oauth

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Step#2 – Get OAuth Client-Id / CLient-Secret
GitHub OAuth 2.0 credentials for Gerrit
integration

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Step#3 – Download Gerrit 2.10 (master)
http://ci.gerritforge.com/job/Gerrit-master

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Step#4 – build GitHub plugin
 git clone https://gerrit.googlesource.com/plugins/github && cd github
 mvn install
[…]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 7.755s
[INFO] Finished at: Sat Mar 15 19:16:23 GMT 2014
[INFO] Final Memory: 57M/449M
[INFO] ------------------------------------------------------------------------

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Step#5 – install OAuth filter and GitHub plugin
> export GERRIT_SITE=/var/gerrit
> mkdir –p $GERRIT_SITE/lib
> cp github-oauth/target/github-oauth*.jar $GERRIT_SITE/lib
> mkdir –p $GERRIT_SITE/plugins
> cp github-plugin/target/github-plugin*.jar $GERRIT_SITE/plugins

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Step#6 – Gerrit setup + replication + singleusergroup
> cd $GERRIT_SITE && java –jar release.war init –d $GERRIT_SITE
*** Gerrit Code Review 2.9-rc1-779-g90fac34-dirty
***
[…]
*** User Authentication
***
Authentication method ? HTTP
Get username from custom HTTP header ? Y
Username HTTP header ? GITHUB_USER
*** Plugins
***
Install plugin singleusergroup version v2.9-rc2-536-g79393b2 [y/N]? y
Install plugin replication version v2.9-rc2-536-g79393b2 [y/N]? y

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Step#7 – Configure GitHub integration
[…]
*** GitHub Integration
***
GitHub URL ? https://github.com
Use GitHub for Gerrit login ? Y
ClientId ? 732819a7b9c9d9a98
ClientSecret ? 6271627a6a7s6s718173642718a9bcacd
HTTP Authentication Header [GITHUB_USER]:

Replay presentation: http://slideshare.net/lucamilanesio
Sign-in: http://gerrithub.io/login
Gerrit book: http://gerrithub.io/book
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Gerrit Code Review with GitHub plugin

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