Plasmoxy/HowToSetupJenkinsCIWithGitLab.md

## HowToSetupJenkinsCIWithGitLab.md

      
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              HowToSetupJenkinsCIWithGitLab.md
            
          
    How to setup Continous Integration for GitLab with Jenkins

Hi, I'd like to share with you how I got my Jenkins CI set up for my private GitLab projects. This is more like a sheet of notes of mine, but I hope it'll help someone as I haven't found any good tutorial for Jenkins+Gitlab on the web yet :D

Here we go:


generate ssh keys on own server -> PUBLIC and PRIVATE ( no passphrase )
go to GitLab profile settings -> SSH keys -> add PUBLIC ssh key to GitLab = this will allow your Jenkins server to access your GitLab
also create full access GitLab API access token for Jenkins on your gitlab profile settings and keep it


install Git + GitLab plugin on Jenkins ( make sure they are enabled (ticked) in Jenkins !!!)
setup git username and mail in manage Jenkins
restart jenkins


go to manage Jenkins -> Gitlab section
create new gitlab connection

set connection name
set gitlab server (https://gitlab.com)
add gitlab API credentials (create them with the API access token from beginning)


create/choose GitLab project
create Jenkins job:

GitLab connection = should be automatically selected to the connection you've just created
Source Code Management -> select Git

Repository URL = copy the SSH url from GitLab project page ( not the https !)
Credentials = now we need to give the SSH PRIVATE key to Jenkins -> Add new Credentials

Kind = SSH Username with private key
Username = your username for git
Private Key -> tick "Enter directly" and enter your PRIVATE key i.e.:

-----BEGIN OPENSSH PRIVATE KEY-----
asfkapokfrpa2kL2K3K32323
-----END OPENSSH PRIVATE KEY-----


set description like Gitlab ssh key or something
click Add and make sure the SSH Credentials are selected


Build Triggers -> Build when a change is pushed to GitLab. :

this will also show you the webhook URL, keep it we'll need it later
probably retarded note ignore this if yo got no errors or running Jenkins on 8080 : notice that if you have wrong  Jenkins address set up in Jenkins, it will use the set up Jenkins address, not the real URL one so make sure the domain is right in the webhook url
IMPORTANT : expand the setting by clicking on Advanced and generate a Secret token = keep this Secret token, we'll use it for gitlab webhook


Build = add your build steps ( for example I use Invoke Gradle Script)
Add post-build action -> Publish build status to GitLab ( this will complete the Continous Integration cycle and show build status on commits on GitLab)
Save the job


finally we set the gitlab webhook up - this will allow gitlab to notify Jenkins of new commits, pull requests etc.


go to your gitlab project -> Settings -> Integrations :

enter the webhook URL that you got from Jenkins job setup
enter the Secret token that you generated on Build Triggers section in job setup
tick Merge request events ( and any other stuff you want to trigger Jenkins with)
Leave SSL verification enabled, if you don't have SSL or something and have problems then untick it
Add webhook
Now you should have a webhook set up
Test it by clicking on Test -> Push requests


try to push to your gitlab project and see the CI ;)


it may look really complicated at first but it's very logical and Jenkins is really useful for both CI and Continuous Delivery as you can customize it as you want


Bonus note for myself: if new Jenkins can't keep a single gradle daemon alive, execute gradle like this -> execute shell command task -> BUILD_ID=dontKillMe gradle build, which won't kill gradle daemon. ( or set BUILD_ID=dontKillMe as environment variable in configure jenkins )


Also branch filtering (separate Jenkins project for dev and master branch ) can be done within the GitLab plugin for Jenkins !