AWS CodeBuild
Fully managed continuous integration service that compiles and tests code
CodeBuild is like having a build server that appears when you need it and disappears when you're done. When you commit code, you need to compile it, run tests, and create artifacts (Docker images, JAR files, etc.). Instead of maintaining build servers 24/7, CodeBuild spins up a build environment, executes your build, and shuts down. You only pay for build minutes. It scales automatically: if 10 developers push code simultaneously, CodeBuild runs 10 builds in parallel. It's like having an infinite pool of build servers that appear on demand.
CodeBuild executes builds defined in buildspec.yml (build commands, test commands, artifact locations). You choose a build environment (Docker image with tools like Maven, npm, Python), compute type (CPU/memory), and environment variables. CodeBuild pulls source from CodeCommit, GitHub, S3, or Bitbucket, executes build phases (install, pre_build, build, post_build), and uploads artifacts to S3.
Key Capabilities
Key features: build caching (speed up builds), VPC support (access private resources), and CloudWatch Logs (build logs).
Gotchas & Constraints
Gotcha #1: CodeBuild charges per build minute; optimize builds to minimize time (use caching, parallel tests). Gotcha #2: Build environments are ephemeral; don't rely on state between builds. Constraints: Maximum 8 hours per build, maximum 255 environment variables, and maximum 50 concurrent builds per account (request increase).
A development team builds a Java application: compile code, run unit tests, run integration tests, create Docker image, and push to ECR. Running builds on developer laptops is slow (20 minutes) and inconsistent. They use CodeBuild: create a buildspec.yml defining build steps, choose a build environment with Java 17 and Docker, and integrate with CodePipeline. When code is pushed, CodeBuild pulls code, compiles it (5 minutes), runs unit tests (3 minutes), runs integration tests (5 minutes), builds Docker image (2 minutes), and pushes to ECR. Total build time: 15 minutes. They enable build caching to cache Maven dependencies, reducing build time to 8 minutes. They run builds in VPC to access private RDS database for integration tests. They configure CloudWatch alarms: if build failure rate exceeds 20%, send SNS alert.
The Result
consistent builds, 60% faster than local builds, and parallel builds for multiple developers.