Configuring Fresh Jobs in Jenkins

Hello, Dear DevOps Automation enthusiast! This post is intended targeted to those who have just started the journey in the Continuous Integration and Continuous Deployment on the Cloud Platforms or On-premises environments.

Pre-requisites

• Latest Stable version of Jenkins installed 
• Jenkins Master is in running state on your machine/VM/Cloud instance
• Able to login to the Jenkins Console

In the left pane, you can click on 'New Item' or Click on the 'Start Using Jenkins' link. The welcome screen shows a link to create a new job!

Jenkins First Job Project creation

You need to enter the value for 

Name for the build project

Type of project

1. Freestyle Project
2. Pipeline
3. Multi-configuration Project
4. Folder
5. GitHub Organization
6. Multibranch Pipeline

Enter the name of the project, Select the 'Freestyle project' for the first time and click on the 'OK' button. New page loads with 6 sections/tabs for build project inputs.

Job Configuration Sections

In Jenkins console we have various Job Configuration types

1. General - Description of the project, Enable project based security, change date pattern for BUILD_TIMESTAMP, Discard old builds enable will help you for easy migration of Jenkins master.
2. Job Notification -  End points, You can enable notification mail when someone changed configuration. Rebuild without asking parameters or we can disable the rebuild for a particular job. You can choose the build requires lockable resources, which means other jobs not allowed when this job is in progress. This project is parameterized enabled then you can add different type Parameters such as String Parameter, Choice Parameter, Password Parameter, Node
4. Jenkins job configuration allows us to use 5 different choices of 'Source code management' as:

a. None

b. CVS

c. CVS Projectset

d. Git

e. Subversion

        Default it is selected as - None

Build Trigger

1. Jenkin's job will be triggered by a 'Build Triggers' section. Here we have Trigger build remotely from scripts, 
2. Build after other projects are built when there is dependency are in the projects
3. Build periodically - This choice asks you on what period you want to execute this job
4. Enable Artifactory trigger - when docker image is pushed you want to run a job 
5. GitHub hook trigger for GITscm polling - requires authentication for webhook accessing GitHub repository
6. Poll SCM - for all types of source code repository updates can trigger the job.

Build Environment

Usually, when we run a build, Jenkins uses /tmp/somerandomnumber.sh in Linux machines as the automatically generated script will create workspace in the slave machine. 

1. Delete workspace before build starts
2. Use secret text(s) or file(s)
3. Provide configuration files
4. send files or execute commands over SSH before the build starts 
5. send files or execute commands over SSH after the build runs
7. Abort the build if it's stuck
8. Add timestamps to the Console Output
9. Ant/Ivy-Artifactory Integration
10. Create a formatted version number
11. Farm Repository
12. Generic-Artifactory Integration
13. Gradle-Artifactory Integration
14. Inject environment variables to the build process
15. Inject passwords to the build as environment variables
16. Inspect build log for published Gradle build scans
17. Maven3-Artifactory Integration
18. Run Xvnc during build
19. Setup Kubernetes CLI (kubectl)
20. With Ant

Build

The build section will have an Execute shell with command text box. where you can enter the shell commands. which will become a shell script.

2. Pipeline Project

If you choose the Pipeline Project then it will have the following sections

1. General

2. Job Notifications

3. Build Triggers

4. Advanced Project options

5. Pipeline 

General 

In the General section, you can see

Enable project-based security

Discard old builds when you check this -> Strategy where you have LogRotation based on - Days to keep builds or Max # of builds to keep 

Advance option - 

Days to keep artifacts - if not empty default 14, artifacts from builds older than this number of days will be deleted, but the logs, history, reports, etc for the build will be kept

Max # of builds to keep with artifacts - if not empty, only up to this number of builds have their artifacts retained

Do not allow concurrent builds

Do not allow the pipeline to resume if the master restarts

GitHub project

Job Notifications

Notify when Job configuration changes

Pipeline speed/durability override

Preserve stashes from completed builds

  Rebuild options: Rebuild Without Asking For Parameters

  Disable Rebuilding for this job

Sidebar Links

This project is parameterized selected then you are allowed to use following parameters:

1. Node
2. String
3. Active Choices parameter -> 
1. Name 
2. Script option will have choice to enter the Groovy script
3. Choice type:  Single select, Multi select, Radio button, Checkbox 
4. Enable Filters
5. The filter starts at 1

Build Triggers

1. Build after other projects are built
2. Build periodically
3. Build whenever a SNAPSHOT dependency is built
4. Enable Artifactory trigger
5. GitHub hook trigger for GITScm polling
6. Poll SCM
7. Disable this project
8. Quiet period
9. Trigger builds remotely (e.g., from scripts)

Advanced Project Options

Click on the 'Advanced' button

Pipeline

Definition - Pipeline script

    the script, Use Groovy sandbox.

After you configured the Job, you have to Apply to save the configuration until now. 

If you are working on the Visual Studio code as editor then you can install the Extention. 

Groovy extension

Jenkinsfile Extension

Continuous Integration Automation: Webhook on GitHub notify Jenkins

Hello Guys, Jenkins CI/CD enthusiast,

In this post, I would like to discuss the implementation of Jenkins Continuous Integration automatic build triggers. Where Jenkins master will be stay connected with the GitHub server with an API token based authentication. To connect with GitHub server we need a personal access token.

Webhook for GitHub and Jenkins integration

1. Create token credentials
2. GitHub server configuration

Webhook is a wonderful solution that will keep track of changes that made to the GitHub repo and notify the Jenkins Master. If we create the item or freestyle project will be triggered automatically.

Create token credentials 

Login into the Jenkins console, Click on the left pane - "Manage jenkins" link. Select the "System Configure" navigates to the new page where you need scroll down till you found the GitHub section.
First we will create the token, look for the "Advanced" button on the rightside. Additional actions: 'Convert login and password to token'.
Select the radio button: "From login and password" which prompt for entering the values for the Login, password that used for GitHub where you have repo. Then use the 'Create token creentials' button at the right end.

Create Token for GitHub on Jenkins

Now the tokens are generated we are ready to connect with the GitHub server. move upwards and enter the following values:

• Your GitHub profile used for connecting
• API URL don't change this 
• Credentials select from the dropdown, where you can find the recently created Token for GitHub - Selected
• Click on the Test connection button will produce the result of connectivity 
• Tick mark the 'manage hooks'

GitHub Server configuration on Jenkins

GitHub Configuration for Webhook

The following simple steps will be enables you to get the webhook on the GitHub that connected to Jenkins Master

1. Log in to your GitHub
2. The top right corner you can find your profile link from that menu select 'Settings'.
3. In the left pane at the bottom, Select the 'Developer Settings'
4. The new page for 'Developer Settings' will have three options, Select 'Personal access tokens' from the menu.

Personal access tokens on GitHub

Now we all set to go for testing the Webhook connectivity with Jenkins

Create a freestyle project for Webhook

On the Jenkins console create new freestyle project
Name it as GitHub-webhook
Project type: Freestyle project
Click on Ok button

Jenkins Project for GitHub Webhook

Source Code Management

Select the Git

Jenkins Source Code management

Build Triggers

Select GitHub hook trigger for GITScm polling

Jenkins Build Trigger

In the Build tab
Select the Execute shell

enter the stuff to know that build triggered in my example used the cat the README.md file which is targeted to modify.

Jenkins build section for CI automation

Save the Jenkins Project.

Go to the GitHub page

Modify the code in the Git repository,

added a line in the README.md file

Automatic Build Triggers

In the Jenkins now the job will be triggered automatically

Jenkins Build automatic triggered and the console output 

Here is the conclusion that Webhook is simple mechanism that will helps Jenkins get notified with code changed in the GitHub.