GitHub Actions vs Jenkins: CI/CD Compared

Two Approaches to CI/CD

GitHub Actions and Jenkins are the two most widely used CI/CD tools, but they take fundamentally different approaches. Jenkins is a self-hosted, open-source automation server that has been around since 2011. GitHub Actions is a cloud-native CI/CD platform built into GitHub, launched in 2019.

Jenkins gives you full control over infrastructure and unlimited customization. GitHub Actions gives you zero infrastructure to manage and tight integration with GitHub. Your choice depends on your team’s needs, existing infrastructure, and how much operational overhead you want to accept.

Architecture Overview

Jenkins

Jenkins runs on a server you manage. It uses a controller-agent architecture:

• Controller (formerly master): Manages the web UI, schedules jobs, and dispatches work.
• Agents (formerly slaves): Execute the actual build steps. Can be VMs, containers, or bare-metal machines.

┌─────────────┐     ┌──────────────┐
│  Controller  │────▶│   Agent 1    │
│  (scheduler) │     │  (Linux x64) │
│              │     └──────────────┘
│              │     ┌──────────────┐
│              │────▶│   Agent 2    │
│              │     │  (Windows)   │
│              │     └──────────────┘
│              │     ┌──────────────┐
│              │────▶│   Agent 3    │
│              │     │  (macOS ARM) │
└─────────────┘     └──────────────┘

You are responsible for provisioning, patching, scaling, and securing all of this infrastructure.

GitHub Actions

GitHub Actions runs on GitHub-hosted runners (managed VMs) or your own self-hosted runners. There is no controller to manage. GitHub handles scheduling, orchestration, and the UI.

┌──────────────┐     ┌───────────────────┐
│   GitHub      │────▶│  GitHub-hosted    │
│   (scheduler) │     │  runner (Ubuntu)  │
│               │     └───────────────────┘
│               │     ┌───────────────────┐
│               │────▶│  GitHub-hosted    │
│               │     │  runner (Windows) │
│               │     └───────────────────┘
│               │     ┌───────────────────┐
│               │────▶│  Self-hosted      │
│               │     │  runner (GPU)     │
└──────────────┘     └───────────────────┘

Each workflow run gets a fresh VM. You do not manage any infrastructure unless you choose self-hosted runners for special requirements.

Pipeline Configuration

GitHub Actions: YAML Workflows

Workflows are defined in .github/workflows/ as YAML files and version-controlled alongside your code:

# .github/workflows/ci.yml
name: CI Pipeline

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  test:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        node-version: [18, 20, 22]
    steps:
      - uses: actions/checkout@v4

      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: ${{ matrix.node-version }}
          cache: 'npm'

      - name: Install dependencies
        run: npm ci

      - name: Run tests
        run: npm test

      - name: Upload coverage
        if: matrix.node-version == 22
        uses: actions/upload-artifact@v4
        with:
          name: coverage
          path: coverage/

  build:
    needs: test
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Build Docker image
        run: docker build -t myapp:${{ github.sha }} .

      - name: Push to registry
        run: |
          echo "${{ secrets.DOCKER_PASSWORD }}" | docker login -u "${{ secrets.DOCKER_USERNAME }}" --password-stdin
          docker push myapp:${{ github.sha }}

Key features visible here:

• Matrix builds run the same job across multiple configurations.
• Reusable actions (actions/checkout, actions/setup-node) handle common tasks.
• Job dependencies (needs: test) control execution order.
• Secrets are managed through the GitHub UI.
• Conditional steps (if:) provide flexibility.

Jenkins: Declarative Pipeline

Jenkins pipelines are defined in a Jenkinsfile using Groovy-based DSL:

// Jenkinsfile
pipeline {
    agent none

    stages {
        stage('Test') {
            matrix {
                axes {
                    axis {
                        name 'NODE_VERSION'
                        values '18', '20', '22'
                    }
                }
                agent {
                    docker {
                        image "node:${NODE_VERSION}"
                    }
                }
                stages {
                    stage('Install & Test') {
                        steps {
                            sh 'npm ci'
                            sh 'npm test'
                        }
                        post {
                            always {
                                junit 'test-results/**/*.xml'
                            }
                        }
                    }
                }
            }
        }

        stage('Build') {
            agent any
            steps {
                script {
                    def image = docker.build("myapp:${env.GIT_COMMIT}")
                    docker.withRegistry('https://registry.example.com', 'docker-credentials') {
                        image.push()
                    }
                }
            }
        }

        stage('Deploy') {
            agent any
            when {
                branch 'main'
            }
            steps {
                sh './deploy.sh'
            }
        }
    }

    post {
        failure {
            slackSend channel: '#builds', message: "Build failed: ${env.JOB_NAME}"
        }
    }
}

Jenkins pipelines are powerful but the Groovy syntax has a steeper learning curve than YAML. The scripted pipeline variant gives you even more flexibility but at the cost of complexity.

Plugin and Action Ecosystem

Jenkins Plugins

Jenkins has over 1,800 plugins covering every tool and service imaginable. Plugins are installed through the Jenkins UI or CLI:

# Install plugins via CLI
java -jar jenkins-cli.jar -s http://localhost:8080/ install-plugin \
    docker-workflow \
    kubernetes \
    slack \
    sonarqube

The plugin ecosystem is Jenkins’ greatest strength and its greatest weakness. Plugins can conflict with each other, fall out of maintenance, or introduce security vulnerabilities. Managing plugin updates and compatibility is a real operational burden.

GitHub Actions Marketplace

GitHub Actions has a marketplace with over 20,000 community-created actions. Using an action is as simple as referencing it in your workflow:

steps:
  # Official action
  - uses: actions/checkout@v4

  # Community action
  - uses: docker/build-push-action@v5
    with:
      push: true
      tags: myapp:latest

  # Action from a specific repository
  - uses: myorg/custom-action@main

Actions are just GitHub repositories, so you can read their source code, fork them, and pin to specific versions. The @v4 suffix pins to a major version tag.

Creating a custom action is also simpler than writing a Jenkins plugin:

# action.yml in your repository
name: 'My Custom Action'
description: 'Does something useful'
inputs:
  api-key:
    description: 'API key for the service'
    required: true
runs:
  using: 'composite'
  steps:
    - run: echo "Running with key ${{ inputs.api-key }}"
      shell: bash

Secrets Management

GitHub Actions stores secrets in the repository or organization settings. They are encrypted at rest and masked in logs:

steps:
  - name: Deploy
    env:
      API_KEY: ${{ secrets.API_KEY }}
      DB_PASSWORD: ${{ secrets.DB_PASSWORD }}
    run: ./deploy.sh

GitHub also supports OpenID Connect (OIDC) for cloud provider authentication without storing long-lived credentials:

permissions:
  id-token: write
  contents: read

steps:
  - uses: aws-actions/configure-aws-credentials@v4
    with:
      role-to-assume: arn:aws:iam::123456789012:role/github-actions
      aws-region: us-east-1

Jenkins offers multiple approaches: the Credentials plugin stores secrets in Jenkins, but many teams integrate with external secret managers:

pipeline {
    environment {
        AWS_CREDS = credentials('aws-credentials-id')
    }
    stages {
        stage('Deploy') {
            steps {
                withCredentials([string(credentialsId: 'api-key', variable: 'API_KEY')]) {
                    sh './deploy.sh'
                }
            }
        }
    }
}

Jenkins credentials are stored on the controller’s filesystem by default, making the controller a high-value target. Integrating with HashiCorp Vault or AWS Secrets Manager adds security but also complexity.

Pricing and Cost

GitHub Actions

• Public repositories: Free and unlimited.
• Private repositories: 2,000 minutes/month free (Free plan), 3,000 minutes (Team), 50,000 minutes (Enterprise).
• Beyond free tier: $0.008/min (Linux), $0.016/min (Windows), $0.08/min (macOS).
• Self-hosted runners: Free (you pay for your own infrastructure).
• Larger runners: 2-64 vCPU options at higher per-minute rates.

Jenkins

• Software: Free and open source.
• Infrastructure: You pay for the servers running Jenkins controller and agents.
• Operational cost: Someone on your team maintains Jenkins. This is often the largest hidden cost.

For a small team with a few pipelines, GitHub Actions is cheaper because there is no infrastructure to manage. For a large organization running thousands of builds per day, Jenkins on your own infrastructure can be more cost-effective, but you must account for the engineering time spent maintaining it.

Scaling

GitHub Actions scales automatically. If you submit 100 matrix jobs, GitHub spins up 100 runners (subject to concurrency limits). You do not provision or manage capacity.

Jenkins requires you to plan capacity. Options include:

• Static agents that are always running (wasteful during off-hours).
• Cloud-based auto-scaling plugins (EC2, Kubernetes) that spin up agents on demand.
• The Kubernetes plugin runs each build in a pod, providing good scaling but requiring a Kubernetes cluster.

// Jenkins: Kubernetes plugin for dynamic agents
pipeline {
    agent {
        kubernetes {
            yaml """
            apiVersion: v1
            kind: Pod
            spec:
              containers:
              - name: node
                image: node:20
                command: ['sleep']
                args: ['infinity']
              - name: docker
                image: docker:dind
                securityContext:
                  privileged: true
            """
        }
    }
    stages {
        stage('Build') {
            steps {
                container('node') {
                    sh 'npm ci && npm test'
                }
                container('docker') {
                    sh 'docker build -t myapp .'
                }
            }
        }
    }
}

Reusability

GitHub Actions: Reusable Workflows and Composite Actions

# .github/workflows/reusable-deploy.yml
on:
  workflow_call:
    inputs:
      environment:
        required: true
        type: string
    secrets:
      deploy_key:
        required: true

jobs:
  deploy:
    runs-on: ubuntu-latest
    environment: ${{ inputs.environment }}
    steps:
      - uses: actions/checkout@v4
      - run: ./deploy.sh ${{ inputs.environment }}
        env:
          DEPLOY_KEY: ${{ secrets.deploy_key }}

# Calling the reusable workflow
jobs:
  deploy-staging:
    uses: ./.github/workflows/reusable-deploy.yml
    with:
      environment: staging
    secrets:
      deploy_key: ${{ secrets.STAGING_DEPLOY_KEY }}

Jenkins: Shared Libraries

// vars/standardPipeline.groovy in a shared library repo
def call(Map config) {
    pipeline {
        agent any
        stages {
            stage('Test') {
                steps {
                    sh "${config.testCommand}"
                }
            }
            stage('Deploy') {
                when { branch 'main' }
                steps {
                    sh "${config.deployCommand}"
                }
            }
        }
    }
}

// Jenkinsfile using the shared library
@Library('my-shared-lib') _
standardPipeline(
    testCommand: 'npm test',
    deployCommand: './deploy.sh'
)

Both approaches work, but GitHub Actions’ reusable workflows are simpler to set up since they are just more YAML files in your repository.

When to Choose GitHub Actions

• Your code is on GitHub and you want zero CI/CD infrastructure.
• Your team is small to medium and does not want to maintain a build server.
• You need fast setup with minimal configuration.
• You want native GitHub integration (PR checks, deployments, environments).
• Your build matrix and concurrency needs are moderate.

When to Choose Jenkins

• You need full control over the build environment and infrastructure.
• You have complex, long-running pipelines that exceed GitHub Actions’ time limits.
• Your organization has strict compliance requirements about where code is built.
• You already have Jenkins expertise and infrastructure in place.
• You need to integrate with on-premises systems that cannot reach GitHub.
• Your build volume makes self-hosted infrastructure more cost-effective.

Wrapping Up

GitHub Actions is the better choice for most teams starting new projects on GitHub. It requires no infrastructure, has a growing marketplace of actions, and integrates seamlessly with pull requests and deployments. Jenkins remains the better choice for large enterprises with complex requirements, on-premises constraints, or existing Jenkins investment. Some organizations use both, with GitHub Actions for standard application CI/CD and Jenkins for specialized build pipelines that need custom infrastructure.