Relation between Git and Jenkins

Git and Jenkins are two tools commonly used together in the software development and deployment process. Here’s an overview of each tool:

  1. Git: Git is a distributed version control system (VCS) that enables developers to track changes in their codebase, collaborate with others, and manage different project versions. Created by Linus Torvalds in 2005, Git has become the most widely adopted version control system for software development.

    It provides a robust and efficient way to manage source code, allowing developers to work on multiple branches concurrently, merge changes, and maintain a complete history of their work. Git can be used with hosting services like GitHub, GitLab, and Bitbucket, which offer additional collaboration features and integrations.
  2. Jenkins: Jenkins is an open-source automation server that helps automate various parts of the software development process, including building, testing, and deploying applications. It is a popular choice for implementing continuous integration and continuous delivery (CI/CD) pipelines.

    Jenkins provides a wide range of plugins and integrations, making it highly customizable and adaptable to different workflows and tools. By automating repetitive tasks, Jenkins enables developers to focus on writing code, reduces human errors, and accelerates the development process.

When used together, Git and Jenkins create an efficient and streamlined software development workflow. Developers can push their code changes to a Git repository, triggering Jenkins to automatically build, test, and deploy the application.

This combination allows for faster feedback, quicker bug detection, and more frequent releases, ultimately resulting in more efficient and reliable software development.

Integrating Git with Jenkins

Integrating Git with Jenkins allows you to automate the building, testing, and deploying of your code whenever changes are pushed to the repository. To set up this integration, follow these steps:

  1. Install Git on your Jenkins server: Ensure that Git is installed on the machine where Jenkins is running. If it’s not installed, you can download it from the official Git website (https://git-scm.com/downloads) and follow the installation instructions for your specific operating system.
  2. Install the Git plugin in Jenkins: To integrate Git with Jenkins, you’ll need to install the Git plugin:
    • Log in to your Jenkins dashboard.
    • Navigate to “Manage Jenkins” > “Manage Plugins”.
    • Go to the “Available” tab and search for “Git plugin”.
    • Select the “Git plugin” from the search results and click “Install without restart” or “Download now and install after restart”, as per your preference.
  3. Configure the Git plugin:
    • Go to “Manage Jenkins” > “Global Tool Configuration”.
    • Scroll to the “Git” section and click “Add Git”.
    • Give your Git installation a name (e.g., “Default Git”) and provide the path to the Git executable on your machine (usually Git or /usr/bin/git). If you don’t know the path, you can run “which git” in the terminal to find it.
    • Save the configuration.
  4. Create a new Jenkins job:
    • Go back to the Jenkins dashboard and click “New Item”.
    • Enter a name for the job, choose “Freestyle project” or “Pipeline” (depending on your preference), and click “OK”.
  5. Configure the job to use your Git repository:
    • In the job configuration page, navigate to the “Source Code Management” section.
    • Select “Git” and enter the URL of your Git repository. If it’s a private repository, you must also provide your credentials.
    • In the “Branches to build” section, specify the branch you want to build (e.g., */master or */main).
    • (Optional) If you want Jenkins to poll your repository for changes, go to the “Build Triggers” section and select “Poll SCM”. Then, provide a schedule using the cron-like syntax (e.g., H/5 * * * * to poll every 5 minutes).
  6. Add build steps:
    • In the “Build” section, click “Add build step” and choose the appropriate build step type, such as “Execute shell” or “Execute Windows batch command”.
    • Enter the commands required to build, test, and deploy your project.
  7. Save the job configuration.

Your Jenkins job is now set up to build, test, and deploy your code whenever changes are pushed to the specified Git repository. You can customize the job by adding post-build actions, setting up notifications, or using additional plugins.

What is Jenkins Pipeline?

Jenkins Pipeline is a powerful feature in Jenkins that allows you to define your entire build, test, and deployment process as code. It provides a domain-specific language (DSL), usually written in Groovy, to create and configure pipelines as part of your source code. 

This approach, also known as “Pipeline as Code, ” promotes versioning, collaboration, and consistency across your development workflow.

A Jenkins pipeline comprises a series of stages and steps representing the different phases of your software development process, such as building, testing, and deploying the application. The pipeline can be defined in a file called Jenkinsfile, stored in your project repository’s root directory.

There are two types of Jenkins pipeline syntax:

  1. Declarative Pipeline: This is a more recent and recommended approach, which provides a simpler, more structured syntax for defining pipelines. It enforces a clear hierarchy and structure, making it easier to understand and maintain.
  2. Scripted Pipeline: This is the older, more flexible syntax that allows for greater customization and control over the pipeline. However, it may be more complex and harder to maintain.

By using Jenkins pipelines, you can automate and streamline your software development process, achieve greater consistency and repeatability, and simplify the management of your build, test, and deployment tasks.

Creating and git and Jenkins pipeline

To create a Jenkins pipeline that uses Git as the source control system, you’ll need to set up a Jenkins job that uses a Jenkinsfile stored in your Git repository. The Jenkinsfile will define the pipeline stages and steps for building, testing, and deploying your project. Here’s how to set up a Git and Jenkins pipeline:

Create a Jenkinsfile in your Git repository: In your project’s root directory, create a file named Jenkinsfile. This file will contain the pipeline configuration using either declarative or scripted syntax. Here’s a simple example of a declarative pipeline:

Commit and push the Jenkinsfile to your Git repository:

  • Add the Jenkinsfile to your Git repository.
  • Commit the changes.
  • Push them to the remote repository.

Set up a new Jenkins pipeline job:

  • Log in to your Jenkins dashboard.
  • Click “New Item” on the dashboard.
  • Enter a name for the job, select “Pipeline”, and click “OK”.

Configure the pipeline job to use your Git repository:

  • In the job configuration page, scroll down to the “Pipeline” section. 
  • In the “Definition” dropdown, select “Pipeline script from SCM”.
  • In the “SCM” dropdown, choose “Git”.
  • Enter the URL of your Git repository in the “Repository URL” field. You’ll need to provide your credentials if it’s a private repository.
  • In the “Branch Specifier” field, specify the branch you want to build (e.g., */master or */main). f. In the “Script Path” field, ensure that it has the correct path to your Jenkinsfile (usually just “Jenkinsfile” if it’s in the root directory of your repository).

Save the job configuration.

Now your Jenkins pipeline is set up to build, test, and deploy your code using the Jenkinsfile stored in your Git repository. Whenever changes are pushed to the specified branch, Jenkins will automatically trigger the pipeline job and execute the stages defined in the Jenkinsfile.

Hope you understand what is the connection between Git and Jenkins and how to create a simple pipeline integrating both.