Jenkinsfile vs. Jenkins Pipeline: Define Automation Workflows

In the Jenkins ecosystem, “Pipeline” and “Jenkinsfile” are foundational concepts for implementing modern Continuous Integration/Continuous Delivery (CI/CD). While closely related, they serve different purposes. Understanding this distinction is essential for effectively automating your software delivery lifecycle.

What is a Jenkins Pipeline?

A Jenkins Pipeline is the overarching framework that defines your entire build, test, and delivery process. It is a suite of plugins that models your software delivery process as a sequence of stages and steps.

• A Stage represents a distinct part of your workflow, such as “Build,” “Test,” or “Deploy.”
• A Step is a single task executed within a stage, like running a shell script or a build command.

A pipeline can be triggered by events like a code commit and can manage complex workflows involving parallel execution, conditional logic, and error handling. Jenkins provides a real-time visual representation of the pipeline’s execution, showing the status of every stage and step.

What is a Jenkinsfile?

A Jenkinsfile is a text file where you define the structure and logic of a Jenkins Pipeline. It is the primary implementation of the “Pipeline as Code” methodology. By writing the pipeline definition in a file, you can treat your CI/CD process just like your application code.

A Jenkinsfile is written using either Declarative or Scripted Pipeline syntax and is stored in your project’s version control repository (e.g., Git) alongside your source code.

Jenkinsfile: Your Pipeline as Code

Jenkinsfile is a text file that defines the steps of a single Jenkins job. It is typically stored in a version control system like Git alongside the application’s source code. Jenkinsfile allows you to define the job as code, which means you can maintain, version, and review the job configuration and the application code. Jenkinsfile can be written in either declarative or scripted syntax.

On the other hand, Jenkins Pipeline is a plugin suite that allows you to create and manage continuous delivery pipelines in Jenkins. Pipeline provides a way to define a Jenkins job as a sequence of stages, each containing one or more steps. 

• Version Controlled:
  Stored alongside your application’s source code in systems like Git, ensuring changes are tracked and easily reverted.
  
• Maintainable:
  Easier to manage and update as your project evolves.
  
• Reviewable:
  Allows for collaboration and feedback on pipeline changes

Various events, such as a code change, a timer, or a manual trigger, can trigger a Pipeline. The pipeline allows you to define complex workflows, including conditional branching, parallelization, and error handling. The definition of a Pipeline can be stored in a Jenkinsfile or defined directly in the Jenkins web UI.

How to Define Your Jenkins Pipeline

Jenkins Pipeline is a suite of plugins that allows you to define and manage continuous delivery pipelines in Jenkins. A pipeline is a sequence of stages containing one or more steps. Various events, such as a code change, a timer, or a manual trigger, can trigger a Pipeline. You can define complex workflows in a Pipeline, including conditional branching, parallelization, and error handling. Pipeline also provides a visual representation of the pipeline, allowing you to see the status of each stage and step in real-time.

Jenkins offers flexible ways to create your pipeline:

1. Jenkinsfile (Best Practice):
   Write your pipeline in a Jenkinsfile and store it in version control for maximum benefits.
   
2. Blue Ocean:
   A visual editor that simplifies pipeline creation and management, especially for those new to Jenkins.\
   
3. Classic UI:
   The traditional way to define pipelines is suitable for simpler workflows.

Summary: The Core Distinction

Concept	Description
Jenkins Pipeline	The what: A CI/CD workflow model consisting of stages and steps that define a delivery process.
Jenkinsfile	The how: A text file that implements a pipeline as code, stored and versioned with your project.

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In short, the Jenkinsfile is the file used to define a Jenkins Pipeline. For robust, scalable, and maintainable CI/CD, always default to using a Jenkinsfile.

Choosing the Right Approach

For most projects, starting with a Jenkinsfile is highly recommended. It offers the best combination of flexibility, maintainability, and collaboration. However, Blue Ocean can be a great starting point for beginners or for simpler projects. The Classic UI is still an option, but it’s generally less efficient for complex pipelines.