Adhering to the principles of immutable infrastructure ensures that no changes can occur to the infrastructure once it is deployed in production. Any modifications, including system patching, configuration changes, adding or removing components, as well as application updates, necessitate the deployment of a new infrastructure version. This version is a copy of the existing one with the applied changes. The new copy is deployed alongside the old one and undergoes thorough, automated testing. If the tests are successful, traffic can be gradually shifted to the new version.
What are benefits of Immutable Infrastructure
Reliability and No Surprises
Immutable infrastructure eliminates surprises post-deployment changes to the infrastructure or applications, ensuring maximum reliability. By avoiding alterations to the deployed infrastructure, it prevents unexpected state changes that could lead to bugs or vulnerabilities, thereby enhancing security and maintaining a consistent, known state.
Atomic and Consistent Changes
Changes are atomic, mirroring the ACID transaction model used in databases. This all-or-nothing approach ensures that changes are fully applied or not at all, preventing partial updates and ensuring that deployments across different environments—development, testing, and production—are consistent and reproducible. The infrastructure's deployment process and configuration are codified, using tools like AWS CloudFormation, enabling identical setups across these environments.
Simplified Management and Enhanced Security
Immutable infrastructure facilitates easy rollback to a previously working version by keeping the old infrastructure as a trusted baseline. This model reduces the attack surface as it eliminates the need for direct access methods such as SSH or RDP for making changes to the operating systems
Risk Minimization and Automation Compatibility
Creating new copies for updates minimizes the risk of service interruptions from unsuccessful changes, simplifying the rollback process to a known-good configuration. This approach is particularly suited to automation and continuous deployment/delivery practices, as it focuses on generating new, identical resource copies rather than complex, in-place changes.
What practices and services can be used for Immutable Infrastructure on AWS
To implement immutable infrastructure on AWS effectively, adhere to the following streamlined practices:
Infrastructure as Code (IaC)
Utilize AWS CloudFormation or Terraform to define your infrastructure and application configurations in code. This approach enables automated, repeatable deployments and version control of your infrastructure, facilitating easy updates and rollbacks.
Continuous Deployment (CI/CD)
Employ AWS CodePipeline and CodeBuild for setting up automated pipelines. These tools automate the deployment of new infrastructure and application versions, ensuring a consistent and error-free rollout process.
Leverage Amazon ECS (Elastic Container Service) or Amazon EKS (Elastic Kubernetes Service) for managing containerized deployments within an immutable infrastructure framework. These services facilitate the orchestration of container deployments, where each container image is immutable. Updates are seamlessly introduced by rolling out new container versions, ensuring a stable and consistent deployment process
Craft pre-configured Amazon Machine Images (AMIs) to encapsulate EC2 and Docker images for containers, effectively creating immutable snapshots that capture the exact state of your application and its environment. For updates, instead of altering existing instances, you generate a fresh AMI and launch new instances derived from this updated AMI.
External State Storage
Keep mutable states such as application data and configurations in external services like Amazon S3 or DynamoDB. This decouples the state from the servers, allowing for
seamless instance replacement without impacting application continuity.
Implement blue/green or red/black deployment methods to safely introduce changes. By creating a parallel environment for the new version and switching traffic after verification, you can ensure minimal disruption and easy rollback if necessary.
Ensure all aspects of your system, including infrastructure code, application code, and configurations, are version-controlled. This enables tracking and managing changes effectively over time.
Leverage AWS Systems Manager Parameter Store and AWS Secrets Manager for runtime configuration and secret management. This avoids hard-coding sensitive information and facilitates flexible application configuration.