How do serverless applications handle version control?

Serverless applications handle version control through a combination of cloud provider features, Infrastructure as Code (IaC) practices, and CI/CD pipelines. Cloud services like AWS Lambda allow developers to publish specific versions of functions, which are immutable snapshots that can be managed independently. For example, when deploying a Lambda function, you can assign a version number (e.g., v1, v2), and use aliases (e.g., prod, staging) to route traffic between versions. This enables safe rollbacks by pointing an alias back to a previous version if issues arise. Similarly, API Gateway stages let you deploy different versions of API configurations, ensuring endpoints can evolve without breaking existing clients.

Version control is also managed through IaC tools like AWS CloudFormation, the Serverless Framework, or Terraform. These tools define serverless resources (functions, databases, APIs) in configuration files (e.g., serverless.yml), which are stored in Git repositories. Changes to these files are tracked, allowing teams to review and deploy updates systematically. For instance, modifying a Lambda function’s memory setting in a serverless.yml file and merging the change via a Git pull request ensures transparency. Environments like development or production are often managed using separate branches or deployment stages (e.g., serverless deploy --stage prod), with each stage referencing its own set of versions and configurations.

CI/CD pipelines automate versioning and deployments. Services like AWS CodePipeline or GitHub Actions can trigger deployments when code is pushed to a specific branch, ensuring consistent versioning across environments. For example, a pipeline might run tests, package code, and deploy a new Lambda version using a tool like the Serverless Framework, then update an alias to direct traffic to the new version. This approach minimizes downtime and allows canary testing by gradually shifting traffic between versions. By combining cloud-native versioning, IaC, and automation, serverless applications maintain clear, auditable change histories while simplifying rollback and environment management.