moved study stuff

Study/CodeBuild/_CodeBuild.md

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+# CodeBuild
+- A fully managed build service in the cloud.
+- Compiles your code, runs unit tests, and produces artifacts that are ready to deploy.
+- Eliminates the need to provision, manage, and scale your own build server
+- Provides prepackaged build environments for popular programming languages and build tools such as Apache, Maven, Gradle, and more.
+- You can also customise environments to use your own build tools
+- Scaled automatically to meet peak build requests.
+
+## Workflow
+1. Trigger a build
+   * You can trigger a build with AWS Console, CLI, SDK or [[_CodePipeline|CodePipeline]] trigger (like pushing to `main`).
+2. Passes the code onto CodeBuild.
+3. You give it a `buildspec.yaml` file, which is generally part of your code base.
+   * You can override it with other build commands.
+4. Push into a bucket, or any other AWS SDK action (I think?)
+
+## Build Environments
+The Docker images that run the CodeBuild, can be managed by [[AWS]] or you. If you need specific software, you need to make an image and upload it to ECR and reference it in the pipeline.
+
+## `buildspec.yml`
+- Provides the build instructions.
+- Needs to be in the root of your project folder (`/buildspec.yml`, relative to the project root) (by default).
+
+### Phases
+1. `install`: only for installing packages in the build environment. (Code gets pulled before this step.)
+2. `pre_build`: commands that run before building. 
+3. `build`: commands that you run during the build.
+4. `post_build`: commands you run after the build.
+
+### Artifacts
+Where we can find the build output
+How it prepares it for uploading to S3 output bucket.
+Basically Zips that go to S3, or ECR images, anything else that SDK can touch.
+
+## Use Cases
+- Generating static pages to host on S3.
+- Run test code & report test coverage. For example, a developer needs to ensure their code passes all tests before being allowed to make/merge a PR.