Terraform Atlantis vs GitHub Actions: Complete IaC Automation Comparison 2025

This post is part of our Atlantis collection.

Core Architecture and Setup

Design Philosophy Differences

Atlantis was built to do one thing: run collaborative Terraform workflows through pull requests. Because it only does that, it needs little configuration and keeps a clear record of who planned and applied what. GitHub Actions is a general-purpose CI/CD platform that you configure for Terraform. It's far more flexible, and it handles plenty of work that has nothing to do with infrastructure.

Implementation Complexity

Atlantis setup requires hosting a service but delivers immediate Terraform workflow benefits:

• Deploy on your infrastructure (Docker, Kubernetes, cloud VMs)
• Configure VCS webhooks and access credentials
• Add provider credentials for Terraform operations

GitHub Actions setup eliminates hosting but needs more workflow configuration:

• Create workflow YAML files in .github/workflows/
• Configure secrets and authentication
• Build custom PR comment systems for plan visibility
• Implement proper state locking mechanisms

Key tradeoff: Atlantis offers complete out-of-the-box Terraform experience with operational overhead, while GitHub Actions eliminates hosting concerns but demands more configuration work.

Cost and Maintenance

Atlantis costs:

• No licensing fees (open-source)
• Infrastructure hosting costs
• Staff time for operational maintenance (updates, monitoring, credential rotation)

GitHub Actions costs:

• GitHub plan costs (includes minutes)
• Additional compute minutes beyond allocation
• Storage costs for artifacts/cache
• Ongoing workflow configuration maintenance

For small-medium teams, GitHub Actions is often more cost-effective. For larger teams with significant Terraform usage, self-hosted Atlantis may provide better cost control.

Workflow Management and Customization

Automation Models

Atlantis implements command-driven workflows centered on pull requests:

• Automatically detects PRs and runs terraform plan
• Posts plan output as PR comments
• Waits for atlantis apply comment from approved reviewers
• Associates locks with specific pull requests

GitHub Actions follows event-driven models triggered by various GitHub events:

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

GitHub Actions lets you run different workflows for different events, but you have to spell out each scenario yourself. It gives you visual run tracking that Atlantis doesn't have. Atlantis keeps everything in the pull request, which feels more cohesive day to day.

Customization Approaches

Atlantis provides focused customization through server-side configuration (repos.yaml) and repository-specific settings (atlantis.yaml):

# atlantis.yaml example
version: 3
projects:
- name: production
  dir: environments/production
  workflow: custom
  apply_requirements: ["approved"]
workflows:
  custom:
    plan:
      steps:
      - run: security-scan
      - init
      - plan
    apply:
      steps:
      - apply

GitHub Actions customizes more broadly through marketplace actions, custom containers, and multi-step workflow orchestration. If your workflows reach well beyond Terraform, GitHub Actions bends to fit. If you'd rather stick to a standard plan-and-apply pattern, Atlantis is the simpler choice.

Security and State Management

Security Models

Atlantis keeps credentials on your controlled environment:

• Provider credentials remain on your server
• Webhook secrets ensure request legitimacy
• Repository allowlists restrict processing
• Apply requirements enforce proper approvals

GitHub Actions uses GitHub's native security capabilities:

• GitHub Secrets management
• OIDC for temporary cloud provider credentials
• Environment protection rules
• Branch protection and required reviews

Critical difference: With Atlantis, infrastructure credentials never leave your environment, while GitHub Actions processes them within GitHub's infrastructure. For organizations with strict security requirements around credential isolation, this may be decisive.

State Locking

Atlantis provides built-in Terraform-specific locking:

• Project and workspace-level locks tied to pull requests
• Automatic lock creation during operations
• PR-based lock tracking and visibility
• Manual unlocking for administrators

GitHub Actions requires explicit locking configuration:

• Backend-based locking (DynamoDB, Azure Blob, etc.)
• GitHub Actions concurrency settings
• Custom implementations for queuing
• Specialized actions for lock management

Atlantis handles concurrency with almost no configuration. GitHub Actions is more flexible, but you have to set it up carefully.

User Experience and Scalability

User Interaction Models

Atlantis centers entirely on pull requests:

• Commands as PR comments (atlantis plan, atlantis apply)
• Plan/apply outputs in PR threads
• Lock status through Atlantis UI
• Minimal context switching

GitHub Actions provides visual but dispersed experience:

• Workflow runs in GitHub Actions UI
• Plan outputs in PR comments (custom implementation needed)
• Status checks on PRs
• Manual approvals through environments

If you want everything tied tightly to the pull request, Atlantis fits better. If you care more about broad CI/CD visibility, GitHub Actions might suit you.

Scalability Considerations

Atlantis scalability:

• Single-instance architecture by default
• Handles hundreds of repositories but can become bottleneck
• Parallel plan/apply capabilities available

GitHub Actions scalability:

• Managed runner infrastructure with automatic scaling
• Self-hosted runners for performance-intensive operations
• Matrix strategies for parallel execution
• Integration with GitHub Enterprise features

For large organizations, GitHub Actions typically offers better scaling through integration with GitHub Enterprise and flexible execution models.

When to Choose Each Tool

Choose Atlantis when:

Atlantis fits teams that work primarily in Terraform and want a purpose-built tool. It suits organizations with strict security requirements that need credential isolation, and teams using multiple VCS platforms that want a consistent workflow across them. It's a strong match for teams heavily invested in pull request workflows, provided you have a dedicated operations team that can manage the extra service.

Choose GitHub Actions when:

GitHub Actions makes sense for GitHub-centric organizations already invested in the ecosystem, and for teams managing both application and infrastructure CI/CD that want unified pipelines. It works well when you'd rather use a managed service than maintain infrastructure yourself, when your workflows are complex and reach beyond standard Terraform operations, or when your projects use GitHub Advanced Security features.

Complementary Approaches

Emerging patterns in 2024-2025 include:

1. GitHub Actions for CI, Atlantis for Terraform: Using Actions for linting/security while Atlantis handles plan/apply
2. Hybrid solutions like Digger and Terrateam providing Atlantis-style workflows using GitHub Actions execution
3. Environment-based separation: GitHub Actions for development, Atlantis for production

A hybrid setup like this cuts down the operational load of running Atlantis yourself while keeping the pull-request workflow teams want.

Implementation Examples

Atlantis Configuration (atlantis.yaml)

version: 3
automerge: true
parallel_plan: true
parallel_apply: true
projects:
- name: infrastructure
  dir: terraform
  workspace: default
  terraform_version: 1.6.0
  autoplan:
    when_modified: ["**/*.tf", "**/*.tfvars"]
    enabled: true
  apply_requirements: ["approved"]
 
workflows:
  default:
    plan:
      steps:
      - run: |
          echo "Running security scan..."
          tfsec .
      - init:
          extra_args: ["-upgrade=false"]
      - plan:
          extra_args: ["-var-file=env.tfvars"]
    apply:
      steps:
      - apply

GitHub Actions Configuration (workflow.yml)

name: 'Terraform'
 
on:
  pull_request:
    branches: [ main ]
  push:
    branches: [ main ]
 
permissions:
  id-token: write
  contents: read
  pull-requests: write
 
jobs:
  terraform:
    name: 'Terraform'
    runs-on: ubuntu-latest
    environment: ${{ github.event_name == 'push' && 'production' || 'development' }}
    
    # Prevent concurrent runs on same ref
    concurrency:
      group: ${{ github.workflow }}-${{ github.ref }}
    
    steps:
    - name: Checkout
      uses: actions/checkout@v4
    
    - name: Setup Terraform
      uses: hashicorp/setup-terraform@v3
      with:
        terraform_version: 1.6.0
    
    - name: Configure AWS Credentials
      uses: aws-actions/configure-aws-credentials@v4
      with:
        role-to-assume: ${{ secrets.AWS_ROLE_ARN }}
        aws-region: us-east-1
        
    - name: Security Scan
      uses: aquasecurity/[email protected]
    
    - name: Terraform Init
      run: terraform init -upgrade=false
    
    - name: Terraform Plan
      id: plan
      if: github.event_name == 'pull_request'
      run: terraform plan -var-file=env.tfvars -no-color -out=tfplan
      continue-on-error: true
    
    - name: Update PR
      uses: actions/github-script@v7
      if: github.event_name == 'pull_request'
      with:
        github-token: ${{ secrets.GITHUB_TOKEN }}
        script: |
          const output = `#### Terraform Plan 📖\`${{ steps.plan.outcome }}\`
          
          <details><summary>Show Plan</summary>
          
          \`\`\`terraform
          ${process.env.TERRAFORM_PLAN}
          \`\`\`
          
          </details>
          
          *Pushed by: @${{ github.actor }}, Action: \`${{ github.event_name }}\`*`;
          
          github.rest.issues.createComment({
            issue_number: context.issue.number,
            owner: context.repo.owner,
            repo: context.repo.repo,
            body: output
          })
    
    - name: Terraform Apply
      if: github.event_name == 'push'
      run: terraform apply -auto-approve -var-file=env.tfvars

Which one fits your team

Atlantis gives you a Terraform workflow that works out of the box, but you have to run and maintain the service. GitHub Actions takes that hosting burden away and gives you more flexibility, but you pay for it in configuration.

In 2024-2025, more teams have started combining the two: Atlantis-style pull-request workflows running on GitHub Actions execution. If you're just getting started with Terraform automation, GitHub Actions is usually the easier place to begin because there's less to operate. If your Terraform practice is already mature and you want a standardized workflow, Atlantis has a lot going for it. And plenty of larger organizations end up using both, letting each handle the part it does best.