# Day 27 Task: Jenkins Declarative Pipeline with Docker

Certainly! Let's delve into the theoretical aspects of integrating Docker into Jenkins declarative pipelines.

### Task 01: Using `sh` Inside the Stage Block

#### Jenkins Declarative Pipeline Overview:

Jenkins declarative pipelines offer a structured and concise way to define the entire build, test, and deployment process. The pipeline script is written in Groovy and allows developers to express the build pipeline as code.

#### Docker Integration:

Integrating Docker into Jenkins pipelines enhances the portability and reproducibility of builds by encapsulating applications and dependencies within containers.

##### Pipeline Configuration:

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1701974177211/11cd5638-115d-4a04-9f01-1d7b25487271.png align="center")

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1701974262938/de076e4f-cb7c-4194-8493-6fdb36ac1ff7.png align="center")

##### Explanation:

* **Agent:** `any` implies the pipeline can run on any available agent.
    
* **Stages:** Stages represent distinct phases in the pipeline. In this case, we have a 'Build' stage.
    
* **Steps:** The 'Build' stage contains a script block, executing the `docker build` command to create an image.
    

##### Clean-Up Stage:

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1701974389390/de4545d4-7b76-4ced-a3c2-5404127f42e7.png align="center")

The 'Clean Up' stage ensures that any existing container with the specified name is removed before the build, preventing errors on repeated job runs.

##### Notes:

* **Reusability:** This pipeline structure is reusable across projects. Simply adjust the Docker build command and image tag based on project requirements.
    

### Task 02: Using Docker Groovy Syntax Inside the Stage Block

#### Docker Groovy Syntax Overview:

The `docker` block in Jenkins allows a more streamlined and expressive way of interacting with Docker within pipeline scripts.

##### Pipeline Configuration:

```bash
pipeline {
    agent any
    
    stages {
        stage('Build') {
            steps {
                script {
                    docker.image('AtometaLokesh/node-todo-cicd:latest').build()
                }
            }
        }
        // Add more stages as needed
    }
}
```

##### Explanation:

* The `docker.image` method sets the Docker image to build.
    
* The `build()` method initiates the Docker image build process.
    

##### Publishing the Docker Image:

This stage demonstrates pushing the built Docker image to a container registry for broader distribution.

##### Notes:

* **Enhanced Readability:** The Docker Groovy syntax enhances readability, making it easier to understand and maintain.
    

### Conclusion:

The integration of Docker into Jenkins declarative pipelines empowers DevOps teams to automate and streamline the containerized application delivery process. These pipelines provide a foundation for building, testing, and deploying Docker images consistently across different projects.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1701974655812/e1ff603a-118c-4f47-811d-6db32f5d1cbc.png align="center")

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1701974722992/c6cdd74c-52fe-4fc3-be1d-b5120c095e5d.png align="center")

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1701974792329/7fa97fab-b257-476f-ab3d-d7938dda5708.png align="center")