Jenkins Cheat Sheet – A Beginner’s Guide to Jenkins

Step 1: Install Java
$ sudo apt update
$ sudo apt install openjdk-8-jdk

Step 2: Add Jenkins Repository
$ wget -q -O - https://pkg.jenkins.io/debian/jenkins.io.key | sudo apt-key add –

Step 3: Add Jenkins repo to the system
$ sudo sh -c 'echo deb http://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'

Step 4: Install Jenkins
$ sudo apt update
$ sudo apt install Jenkins

Step 5: Verify installation
$ systemctl status Jenkins

Step 6: Once Jenkins is up and running, access it from the link:
http://localhost:8080

In the filter text field enter the name of the plugin you want to install.

Jenkins provides the option of choosing from different types of jobs to build your project.

Below are the types of jobs you can choose from:

• Freestyle

Freestyle build jobs are general-purpose build jobs, which provides maximum flexibility. It can be used for any type of project.

• Pipeline

This project runs the entire software development workflow as code. Instead of creating several jobs for each stage of software development, you can now run the entire workflow as one code.

• Multiconfiguration

The multiconfiguration project allows you to run the same build job on different environments. It is used for testing an application in different environments.

• Folder

This project allows users to create folders to organize and categorize similar jobs in one folder or sub folder.

• GitHub Organization

This project scans your entire GitHub organization and creates Pipeline jobs for each repository containing a Jenkinsfile

• Multibranch pipeline

This project type lets you implement different Jenkinsfiles for different branches of the same project.

Jenkins Dashboard -> Manage Jenkins -> Manage Plugins -> Available  

In the filter text field enter the name of the plugin you want to install.

Step 1: Create 3 freestyle Jobs (Job1, Job2, Job3)

Step 2: Chain the 3 Jobs together
Job1 -> configure -> Post Build -> Build other projects -> Job2
Job2 -> configure -> Post Build -> Build other projects -> Job3

Step 3: Create a build pipeline view
Jenkins Dashboard -> Add view -> Enter a name -> Build pipeline view -> ok ->
configure -> Pipeline flow -> Select Initial job -> Job1 -> ok

Step 4: Run the Build Pipeline

node {
      scripted pipeline code
}

• Declarative pipeline

Code is written locally in a file and is checked into a SCM and is enclosed within the pipeline block

pipeline {
      declarative pipeline code
}

The below fundamentals are common to both, scripted and declarative pipeline:

1. Pipeline: A user defined block which contains all the stages. It is a key part of declarative pipeline syntax.
2. Node: A node is a machine that executes an entire workflow. It is a key part of the scripted pipeline syntax.
3. Agent: instructs Jenkins to allocate an executor for the builds. It is defined for an entire pipeline or a specific stage.

        It has the following parameters:

• Any: Runs pipeline/ stage on any available agent
• None: applied at the root of the pipeline, it indicates that there is no global agent for the entire pipeline & each stage must specify its own agent
• Label: Executes the pipeline/stage on the labelled agent.
• Docker: Uses docker container as an execution environment for the pipeline or a specific stage.

4. Stages: It contains all the work; each stage performs a specific task.
5. Steps: steps are carried out in sequence to execute a stage