Continuous Integration Setup for Clojure Applications

19.6.4 Continuous Integration Setup

Continuous Integration (CI) is a critical practice in modern software development, enabling teams to automate the process of building, testing, and deploying applications. For Clojure developers, setting up a CI pipeline can streamline workflows, reduce errors, and ensure that code changes are integrated smoothly. In this section, we’ll explore how to set up a CI pipeline for Clojure applications using popular tools like GitHub Actions, Travis CI, and Jenkins.

Understanding Continuous Integration

Continuous Integration is a development practice where developers integrate code into a shared repository frequently, ideally several times a day. Each integration is verified by an automated build and test process, allowing teams to detect problems early.

Key Benefits of CI

• Early Detection of Errors: Automated testing helps catch bugs as soon as they are introduced.
• Improved Collaboration: Frequent integrations encourage collaboration and reduce integration conflicts.
• Faster Feedback: Developers receive immediate feedback on the impact of their changes.
• Consistent Builds: Automated builds ensure consistency across different environments.

Setting Up a CI Pipeline

A CI pipeline typically involves the following steps:

1. Code Checkout: The CI server checks out the latest code from the repository.
2. Build: The application is built using a build tool like Leiningen or tools.deps.
3. Test: Automated tests are executed to verify the code’s correctness.
4. Deploy: The application is deployed to a staging or production environment.

Let’s explore how to implement these steps using different CI tools.

GitHub Actions

GitHub Actions is a powerful CI/CD platform that allows you to automate workflows directly from your GitHub repository.

Setting Up GitHub Actions for Clojure

1. Create a Workflow File: In your repository, create a .github/workflows/ci.yml file.

name: Clojure CI

on:
  push:
    branches:
      - main
  pull_request:
    branches:
      - main

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
    - name: Checkout code
      uses: actions/checkout@v2

    - name: Set up JDK 11
      uses: actions/setup-java@v2
      with:
        java-version: '11'

    - name: Install Clojure
      run: |
        curl -O https://download.clojure.org/install/linux-install-1.10.3.967.sh
        chmod +x linux-install-1.10.3.967.sh
        sudo ./linux-install-1.10.3.967.sh        

    - name: Build with Leiningen
      run: lein deps

    - name: Run tests
      run: lein test

Explanation:

• Checkout Code: Uses the actions/checkout action to pull the latest code.
• Set up JDK: Installs Java 11, which is required for running Clojure.
• Install Clojure: Downloads and installs Clojure.
• Build and Test: Uses Leiningen to install dependencies and run tests.

Advantages of GitHub Actions

• Integrated with GitHub: Seamless integration with GitHub repositories.
• Customizable Workflows: Define workflows using YAML files.
• Community Support: Access to a wide range of pre-built actions.

Travis CI

Travis CI is a popular CI service that integrates with GitHub and offers a simple setup for open-source projects.

Setting Up Travis CI for Clojure

1. Create a .travis.yml File: Add the following configuration to your repository.

language: clojure
jdk:
  - openjdk11

script:
  - lein deps
  - lein test

Explanation:

• Language: Specifies Clojure as the programming language.
• JDK: Uses OpenJDK 11.
• Script: Defines the build and test commands.

Advantages of Travis CI

• Easy Setup: Minimal configuration required.
• Free for Open Source: Free for public repositories.
• Extensive Documentation: Comprehensive guides and examples.

Jenkins

Jenkins is a widely-used open-source automation server that provides hundreds of plugins to support building, deploying, and automating any project.

Setting Up Jenkins for Clojure

1. Install Jenkins: Follow the official installation guide to set up Jenkins on your server.

2. Create a New Job: In Jenkins, create a new Freestyle project.

3. Configure Source Code Management: Connect your GitHub repository.

4. Add Build Steps:

   • Execute Shell: Add a shell script to build and test your application.

#!/bin/bash
set -e

# Install dependencies
lein deps

# Run tests
lein test

Advantages of Jenkins

• Highly Customizable: Extensive plugin ecosystem.
• Self-Hosted: Full control over the CI environment.
• Scalable: Suitable for large projects and teams.

Comparing CI Tools

Best Practices for CI in Clojure

• Keep Builds Fast: Optimize build and test times to provide quick feedback.
• Use Caching: Cache dependencies to speed up builds.
• Run Tests in Parallel: Leverage parallel test execution to reduce build times.
• Monitor Build Health: Regularly review build logs and address failures promptly.

Try It Yourself

Experiment with the CI setup by modifying the workflow files:

• Add a Deployment Step: Extend the CI pipeline to deploy the application to a cloud provider.
• Integrate with Slack: Set up notifications to alert your team of build status changes.

Summary and Key Takeaways

Setting up a CI pipeline for Clojure applications can significantly enhance your development workflow. By automating the build, test, and deployment processes, you can ensure that your code is always in a deployable state. Whether you choose GitHub Actions, Travis CI, or Jenkins, each tool offers unique advantages that can be tailored to your project’s needs.

Exercises

1. Set up a CI pipeline for a sample Clojure project using GitHub Actions. Ensure that the pipeline runs tests on every push to the main branch.
2. Extend the Travis CI configuration to include a deployment step that pushes the application to a staging environment.
3. Configure Jenkins to build and test a Clojure project, and set up email notifications for build failures.

By mastering CI tools and practices, you’ll be well-equipped to maintain high-quality Clojure applications and collaborate effectively with your team.

Quiz: Mastering Continuous Integration for Clojure Applications