CodeBuild: Project, buildspec.yml, and the First Build
Build the build stage: create a CodeBuild project wired to the CodeCommit repo, write buildspec.yml defining the build phases, run a real build, then read the CloudWatch log to see how each phase runs. Dissect the mechanism — CodeBuild stands up a temporary container, runs buildspec in phase order, pushes the artifact to S3 and logs to CloudWatch.