CI/CD Pipelines for Containerized Applications: Automating Builds, Tests, and Deployments
Published: 2024-05-21 11:45:05

Containerization has become a popular approach for deploying applications due to its flexibility, portability, and scalability. However, manually building, testing, and deploying containerized applications can be time-consuming and error-prone. Continuous Integration/Continuous Deployment (CI/CD) pipelines can help automate these processes, improving efficiency and reliability. This article discusses the technical aspects of CI/CD pipelines for containerized applications using popular tools such as Jenkins, GitLab CI/CD, and CircleCI.

**CI/CD Pipeline Stages**

A typical CI/CD pipeline for containerized applications consists of the following stages:

1. Build: The build stage involves building the container image and pushing it to a container registry.
2. Test: The test stage involves running automated tests against the container image to ensure that it meets quality standards.
3. Deploy: The deploy stage involves deploying the container image to a production environment.

**CI/CD Pipeline Tools**

There are several tools available for building CI/CD pipelines for containerized applications. Here are some popular options:

1.**Jenkins:** Jenkins is an open-source automation server that can be used to build CI/CD pipelines for containerized applications. Jenkins supports plugins for building Docker images, running tests, and deploying to Kubernetes.

2. **GitLab CI/CD:** GitLab CI/CD is a built-in CI/CD tool in GitLab that can be used to build, test, and deploy containerized applications. GitLab CI/CD supports Docker integration and provides a simple YAML configuration file for defining pipeline stages.

3. **CircleCI:** CircleCI is a cloud-based CI/CD tool that can be used to build, test, and deploy containerized applications. CircleCI supports Docker integration and provides a simple configuration file for defining pipeline stages.

Example CI/CD Pipeline for Containerized Applications using Jenkins

Here is an example of a CI/CD pipeline for a containerized application using Jenkins:

**1. Build Stage:**
```groovy
stage('Build') {
  steps {
    script {
      docker.withRegistry('https://gcr.io', 'gcloud-credentials') {
        def image = docker.build("my-app:${env.BUILD_NUMBER}")
        image.push()
      }
    }
  }
}
```
**2. Test Stage:**
```groovy
stage('Test') {
  steps {
    script {
      docker.image('my-app:${env.BUILD_NUMBER}').inside('-e "DB_HOST=my-db"') {
        sh 'make test'
      }
    }
  }
}
```
**3. Deploy Stage:**
```groovy
stage('Deploy') {
  steps {
    script {
      withKubeConfig([credentialsId: 'kubeconfig']) {
        kubectl delete deployment my-app
        kubectl create deployment my-app --image=gcr.io/my-project/my-app:${env.BUILD_NUMBER}
      }
    }
  }
}
```
Example CI/CD Pipeline for Containerized Applications using GitLab CI/CD

Here is an example of a CI/CD pipeline for a containerized application using GitLab CI/CD:

**1. Build Stage:**
```yaml
build:
  stage: build
  image: docker:latest
  services:
    - docker:dind
  script:
    - docker build -t my-app:${CI_COMMIT_SHA} .
    - docker push my-app:${CI_COMMIT_SHA}
```
**2. Test Stage:**
```yaml
test:
  stage: test
  image: my-app:${CI_COMMIT_SHA}
  services:
    - my-db:latest
  script:
    - make test
```
**3. Deploy Stage:**
```yaml
deploy:
  stage: deploy
  image: gcr.io/cloud-builders/kubectl
  script:
    - kubectl delete deployment my-app
    - kubectl create deployment my-app --image=my-app:${CI_COMMIT_SHA}
```
Example CI/CD Pipeline for Containerized Applications using CircleCI

Here is an example of a CI/CD pipeline for a containerized application using CircleCI:

**1. Build Stage:**
```yaml
build:
  docker:
    - image: circleci/docker:latest
  steps:
    - checkout
    - run:
        name: Build Docker image
        command: |
          docker build -t my-app:${CIRCLE_SHA1} .
          docker push my-app:${CIRCLE_SHA1}
```
**2. Test Stage:**
```yaml
test:
  docker:
    - image: my-app:${CIRCLE_SHA1}
  steps:
    - run:
        name: Run tests
        command: make test
```
**3. Deploy Stage:**
```yaml
deploy:
  docker:
    - image: circleci/kubectl:latest
  steps:
    - run:
        name: Deploy to Kubernetes
        command: |
          kubectl delete deployment my-app
          kubectl create deployment my-app --image=my-app:${CIRCLE_SHA1}
```

## Conclusion

[CI/CD pipelines](https://platformengineers.io/services/ci-cd-implementation/) for containerized applications can help automate builds, tests, and deployments, improving efficiency and reliability. Popular tools such as Jenkins, GitLab CI/CD, and CircleCI provide features for building CI/CD pipelines for containerized applications. By following best practices for CI/CD pipelines, [platform engineers](www.platformengineers.io) can ensure that containerized applications are built, tested, and deployed consistently and reliably.