How to install Jenkins

First, ensure to have OpenJDK with Java 8 or 11 installed on your computer.

Then in a terminal, type:

wget -q -O - https://pkg.jenkins.io/debian/jenkins.io.key | sudo apt-key add -

sudo sh -c 'echo deb https://pkg.jenkins.io/debian-stable binary/ > \ /etc/apt/sources.list.d/jenkins.list'

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sudo apt-get update -y

sudo apt-get install jenkins -y

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To run the software you need: sudo systemctl start jenkins

For the first time you will launch Jenkins, you have to type: sudo systemctl enable jenkins

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Now, to open Jenkins you can browse to http://localhost:8080

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sudo cat /var/lib/jenkins/secrets/initialAdminPassword

On the next page you can install suggested plugins and then choose username and password for the new admin account.

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How to setup Jenkins tests

First, to link it to a GitHub repository using a GitHub App, just follow this tutorial: https://github.com/jenkinsci/github-branch-source-plugin/blob/master/docs/github-app.adoc

To create a job, click on New item in the left menu and then create a Freestyle project

Then, in the Build section, choose Execute shell and enter your commands to run tests

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How to automate tests

In Manage Jenkins -> Configure System, add https://gits-15.sys.kth.se/api/v3 API URL and API endpoint in GitHub server and in GitHub Enterprise servers

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Send a message on Slack at every push

To automate tests after each push, you can follow this video tutorial: https://www.youtube.com/watch?v=Moe2D3Rstc4

Important information: when you create the webhook, for the Payload URL, http://localhost:8080/github-webhook/ and replace localhost by your IP address

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To send the results of the tests in a Slack channel, you can follow this tutorial: https://medium.com/@gustavo.guss/jenkins-and-slack-integration-fbb031cd7895

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Launch a test at every pull request

For that, you should install Github Pull RequestBuilder plugin. Then you can follow this tutorial: https://devopscube.com/jenkins-build-trigger-github-pull-request/ with some specific information

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Because we use GitHub Enterprise, the API URL to enter in system configuration is https://gits-15.sys.kth.se/api/v3

And then you should add the webhook Payload URL as Jenkins URL override

And link it with the GitHub app created previously as credential.

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For the webhook, you can't use the same as for push automation. So you have to create a new one with the Payload URL format like in the tutorial.