What is Declarative Pipelines?

In Jenkins, a declarative pipeline is a way to define your continuous integration and continuous delivery (CI/CD) pipelines using a structured and human-readable syntax.

Declarative Pipelines VS Freestyle Projects:

Declarative Pipelines

• Structured Syntax: Organized, predefined structure for pipelines.

• Ease of Use: Simple and easy to understand, even for non-scripters.

• Best Practices: Encourages separation of concerns and code reusability.

• Stage Visualization: Offers graphical view of pipeline stages.

• Limited Customization: May lack flexibility for very complex workflows.

• Version Control: Pipeline configurations can be versioned alongside code.

Freestyle Projects:

• Flexible Configuration: More free-form configuration of build steps and actions.

• No Scripting Required: Configuration through Jenkins UI, no scripting needed.

• Simplicity for Basic Tasks: Suitable for straightforward build and deploy tasks.

• Reproducibility Challenges: Reproducing consistent configurations can be harder.

• Less Version Control: Configurations are stored within Jenkins, less version control.

Setting Up Job: Declarative pipeline

With Jenkins all set up, it's time to create another job. Let's take a look at how you can do that:

1. Create a New Job:

   • From the Jenkins dashboard, click "New Item."

   • Name your job, e.g. "simple-declarative"

   • Select "pipeline" and click "OK."

     

2. Job Configuration:

• In the job configuration page under "general", enter a description for the job, e.g. "This is a simple builds"

• 

1. Pipeline:

   In this section, we have to write pipeline syntax (also called groovy syntax) with the following stages

   • Code

   • Build

   • Test

   • Deploy

1. Building Stages:

   In one single click using the above command we have now built the pipeline with stages in it.

1. A successful Jenkins pipeline:

   If every stage is built correctly without any errors then this means that the whole pipeline is built successfully.

1. A failed Jenkins pipeline:

   It is also equally important to see how does a failed pipeline looks like and if any of the stages fails then all the next stages will fail.

Conclusion:

Declarative pipelines offer a balance between simplicity and flexibility, and they are recommended for most use cases. However, for more complex or custom workflows, you might need to use a Scripted Pipeline, which provides a more extensive scripting capability using Groovy.

Hope you like my post. Don't forget to like, comment, and share.