Embracing Best Practices for Writing Terraform Infrastructure as Code (IaC) for AWS
Harnessing the power of Infrastructure as Code (IaC) can be transformative for any organisation, especially with the use of Terraform, a widely adopted multi-cloud tool. When used to manage AWS infrastructure, it provides consistency, scalability, and transparency. In this blog post, we’ll delve into the best practices for writing Terraform IaC for AWS.
1. Modularize Your Code:
Breaking your code down into reusable modules promotes code reusability and maintainability. A module encapsulates a set of infrastructure resources that logically belong together and provides a clear and easy way to manage and organize your infrastructure.
2. Consistent Formatting:
Consistent formatting of your Terraform scripts enhances readability and ease of maintenance. Terraform provides a built-in formatter tool, terraform fmt, which automatically updates your scripts to align with the official Terraform coding standards.
3. Leverage .tfvars for Sensitive Data:
To handle sensitive data, use input variable files (.tfvars). This approach is beneficial when managing AWS credentials, database credentials, or other sensitive data. Remember never to commit sensitive data to your version control system. Instead, use AWS Secrets Manager or AWS Systems Manager Parameter Store.
4. Plan before Apply:
Always run terraform plan before terraform apply to preview the changes that will be made to your infrastructure. This practice helps prevent unexpected changes from being deployed.
5. Use Terraform Workspaces:
Terraform workspaces allow you to manage multiple environment states like development, staging, and production within the same configuration. This practice minimizes the chances of accidentally making changes in the wrong environment.
6. Incorporate Remote State Management:
The Terraform state file keeps track of the resources Terraform creates. To manage state files effectively, especially in a team, use remote state management. AWS S3, combined with DynamoDB for state locking, can provide robust remote state management for Terraform.
7. Automate with CI/CD:
Integrating your Terraform code with a Continuous Integration/Continuous Deployment (CI/CD) pipeline allows automatic testing and deployment of your infrastructure. AWS CodePipeline or Jenkins are excellent choices for automating your IaC deployments.
8. Use IAM Roles and Policies:
Assign IAM roles to your AWS resources and use policies to define what actions these resources can perform. This ensures that your resources only have the minimum permissions necessary to function, enhancing your AWS infrastructure’s security.
9. Tag Your Resources:
Tagging AWS resources provides a way to categorise and manage resources based on criteria such as owner, purpose, or environment. This practice is helpful for cost tracking, ownership identification, and implementing policy conditions.
10. Keep Your Terraform Version Up to Date:
Stay up-to-date with the latest Terraform version. Each new version comes with bug fixes, improvements, and new features that can help you write more efficient and effective IaC.
11. Use Data Sources:
Data sources allow data to be fetched or computed for use elsewhere in Terraform configuration. This enables you to use information defined outside of Terraform, defined by another separate Terraform configuration, or modify and return the results of a resource.
12. Validate Your Code:
Validation is an important step to ensure that the changes you plan to introduce with your Terraform script won’t break anything. Always validate your code using terraform validate before planning and applying your changes.
13. Implement a Backup Strategy:
Despite the use of remote state management, it’s also important to have a backup strategy in place. Regularly backing up your state file to a secure location can prevent loss of data in the event of accidental deletions or changes.
14. Use a Private Terraform Registry:
If your organisation is large and uses a lot of shared modules, it might make sense to set up a private Terraform registry. This allows teams to discover and distribute modules within the organisation more effectively.
15. Consider Resource Dependency:
Terraform creates resources in the order in which they are defined in the code, unless explicit dependencies are set. Use the depends_on argument to handle resource dependencies and ensure correct order of creation, modification, or deletion.
16. Secure Your Remote State File:
While remote state is a good practice, it’s equally important to secure it. If using an S3 bucket for remote state, ensure it is private, enable versioning, and encrypt the bucket contents at rest.
17. Use the terraform-docs Tool:
The terraform-docs tool can automatically generate documentation for your Terraform modules, which can help to keep your project documentation up-to-date and make your modules easier to use and understand.
Absolutely, here are few additional best practices for using Terraform:
18. Lock Terraform State:
Terraform uses state data to remember resources it manages, which are stored by default in a local file named “terraform.tfstate”. If working as part of a team, it’s important to lock your Terraform state file to prevent others from modifying it simultaneously, which can lead to inconsistencies.
19. Design for Destruction and Recreation:
When designing your infrastructure, keep in mind that you should be able to tear down and recreate everything as needed. To achieve this, avoid manually modifying the infrastructure that Terraform is managing, as manual changes can lead to discrepancies between the actual infrastructure and Terraform state.
20. Limit the Blast Radius:
Apply the principle of least privilege. Instead of having one IAM user that can modify all resources, create multiple IAM users or roles with limited scopes of influence. This way, even if one user gets compromised, not all of your infrastructure would be at risk.
21. Use Terraform Cloud:
For teams, consider using Terraform Cloud, which provides cost-effective and scalable remote state management and collaboration features.
22. Use Provider Alias for Multi-environment:
If you have resources in different AWS environments (like different regions or accounts), you can use the ‘alias’ feature in Terraform’s provider block to differentiate between different environments.
23. Follow Semantic Versioning for Modules:
Following semantic versioning for your modules can prevent unnecessary issues in production. This way, you can introduce and test new features without disturbing stable environments and ensure a consistent production environment.
24. Keep Secrets out of Your Terraform Scripts:
Never hard-code sensitive information in your Terraform scripts. Use a secure storage system like AWS Secrets Manager, and pull secrets as needed.
Remember, Terraform is a very powerful tool. With power comes responsibility. Following best practices when writing Infrastructure as Code is essential to keep your infrastructure secure, efficient, and maintainable.
Embracing these best practices when writing Terraform IaC for AWS can significantly enhance your IaC’s efficiency, readability, maintainability, and security. As with any technology, the key is to keep learning and refining your approach as the platform continues to evolve. Happy Terraforming!