Amazon Web Services (AWS) is a highly popular suite of cloud services, and AWS CodeBuild is one of the essential tools in its arsenal. A key component in AWS CodeBuild projects is the buildspec.yml file, which provides a sequence of instructions necessary for building and testing your software. If you are a novice stepping into AWS CodeBuild, this guide will provide a step-by-step process to master the basics of writing your first buildspec.yml file.
Understanding a buildspec.yml File
The buildspec.yml file is a collection of build commands and related settings in YAML format used by AWS CodeBuild to run a build. This file can be included in the root of your source code or an alternative location of your choice.
When a build is run in AWS CodeBuild, the buildspec.yml file provides instructions about how the build environment should behave. It can contain several sections, each of which serves a different purpose in the build process. The major sections include `version`, `phases`, `artifacts`, `cache`, `environment`, and `reports`.
Writing Your First buildspec.yml File
With a basic understanding of the structure, let’s dive into writing a simple buildspec.yml for a Node.js application that will install the necessary dependencies and build the code:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | version: 0.2 phases: install: runtime-versions: nodejs: 18 commands: - echo Installing dependencies... - npm install build: commands: - echo Build started on `date` - echo Compiling the Node.js code... - npm run build artifacts: files: - '**/*' discard-paths: yes |
In this buildspec.yml, we have defined commands to install dependencies with npm and build the Node.js code. The artifacts section specifies that all files in the project should be saved after the build is completed.
Understand Sections of buildspec.yml File
Version
The version section is used to specify the buildspec.yml file version. Currently, two versions are available – 0.1 and 0.2, with 0.2 being the latest and most commonly used.
1 | version: 0.2 |
Phases
The phases section, perhaps the most vital part of the buildspec.yml file, consists of sequences of commands that AWS CodeBuild will execute. The key phases are install, pre_build, build, and post_build.
- install: Used to specify the installation instructions needed for the build. Here, you may define commands to install the necessary dependencies for your project.
- pre_build: This phase is used to set up prerequisites before the actual build starts.
- build: The main phase where the build commands are listed.
- post_build: This phase is used for cleanup operations, sending notifications, or any other steps that need to be performed after the build is completed.
1 2 3 4 5 6 7 8 9 10 11 12 13 | phases: install: runtime-versions: nodejs: 18 commands: - echo Installing dependencies... - npm install build: commands: - echo Build started on `date` - echo Compiling the Node.js code... - npm run build |
Artifacts
The artifacts section is used to specify the files or directories that will be prepared and saved by CodeBuild after each build run.
1 2 3 4 | artifacts: files: - '**/*' discard-paths: yes |
Conclusion
Writing a buildspec.yml file can initially seem daunting, but understanding its structure and components helps demystify the process. This article has provided an introduction to writing your first buildspec.yml file, and with practice, you will be able to construct more complex files to suit any build environment and process. Keep learning, and happy building!
