Webhooks are configured between supported Git providers such as GitHub/Bitbucket and AWS CodeBuild. The Git provider sends events whenever a PR is created or updated. In the case of AWS CodeCommit, it’s set up to trigger a Lambda function on those events, which in turn kicks off the build within AWS CodeBuild. AWS CodeBuild accepts Git PR events and compresses the PR codebase in an archive. This archive is stored in the Git Artifacts Amazon S3 bucket; AWS CodeBuild posts a message on an Amazon Simple Queue Service (Amazon SQS) queue about a fresh codebase ready to be processed. An AWS Lambda function polling the Amazon SQS queue consumes the message. The Lambda function starts the CI process and moves the new codebase to the Pipeline Source Amazon S3 bucket location. This S3 bucket acts as the source of AWS CodePipeline. The Lambda function also checks any automation prerequisite, like status of third-party resources or environments consumed by CI, and removes obsolete codebase from the backlog if updates are submitted against a PR. AWS CodePipeline orchestrates CI workflow for the specific project under development by statically validating the codebase, running unit tests, building artifacts, creating a preview environment where the application is deployed, and executing integration and endto-end (E2E) tests. Amazon EventBridge monitors the changes in pipeline stages; a Lambda function updates the PR based on status of events generate
