A Complete Guide to AWS CodeBuild: From Basics to Advanced Use Cases - Part 1

Introduction

Overview of AWS CodeBuild

AWS CodeBuild is a fully managed continuous integration (CI) service that automates the process of building and testing code. It enables you to compile source code, run tests, and produce ready-to-deploy software packages. CodeBuild scales automatically to meet your build volume, and you only pay for the build time you consume.

What is AWS CodeBuild?

AWS CodeBuild is part of the broader AWS DevOps suite, and its purpose is to streamline the process of compiling, testing, and packaging code for deployment. It is fully managed, meaning you don’t need to manage your own build servers or worry about their maintenance.

In simple terms, CodeBuild can be thought of as a “robot” that reads your source code, makes sure there are no issues, and prepares the code for the next step in your software delivery pipeline.

(Q: What exactly does AWS CodeBuild do?)
AWS CodeBuild automates the process of “building” your software. Building, in this context, means turning raw code (written in languages like Java, Python, or Node.js) into an executable program. During this process, it also runs tests to check for errors and prepares everything for deployment to production or staging environments.

Example:
Suppose you have a simple Python application that takes data and generates reports. When you push your changes to GitHub, CodeBuild picks up your code, installs any necessary dependencies (like Python packages), and runs the code to ensure everything works.

Key Features of AWS CodeBuild

1. Fully Managed Service
   AWS CodeBuild is serverless, meaning AWS takes care of the infrastructure, scaling, and maintenance. You only focus on the build process itself.

2. Scalability
   It automatically scales up or down based on the number of builds. If you have multiple developers pushing code simultaneously, AWS CodeBuild can handle it without you needing to configure additional servers.

3. Customizable Build Environments
   You can use predefined build environments provided by AWS or create your own custom Docker images. This flexibility is great when your project has specific dependencies that need to be installed.

4. Integration with Other AWS Services
   AWS CodeBuild integrates seamlessly with other AWS services like CodePipeline, CodeDeploy, CloudWatch, and IAM, enabling you to build, test, and deploy applications with ease.

5. Pay-Per-Use Pricing
   You only pay for the actual build time used. There are no upfront fees or long-term commitments.

(Q: Why should I use AWS CodeBuild instead of managing my own build servers?)
AWS CodeBuild handles the complex tasks of managing build servers, scaling, and maintaining the environment, which saves you time and money. You don’t need to worry about server uptime, scaling, or configuration. You just push your code, and AWS CodeBuild takes care of the rest.

Example:
Let’s say you are building a Node.js application. If you were managing your own servers, you would have to worry about configuring the right version of Node.js, installing dependencies, and maintaining the environment. With AWS CodeBuild, you simply provide your code, and it runs in the cloud without you worrying about the infrastructure.

How AWS CodeBuild Fits into DevOps

AWS CodeBuild is a core component of a DevOps pipeline, helping automate and streamline the process of software development. DevOps involves automating all stages of software delivery, from coding to testing and deployment, and AWS CodeBuild fits right in by automating the build and test phase.

(Q: What is DevOps and why is it important for CodeBuild?)
DevOps is a set of practices that combine software development (Dev) and IT operations (Ops) to shorten the software development lifecycle. AWS CodeBuild plays a crucial role in DevOps by automating the building and testing of your software, ensuring that code changes are properly validated before being deployed to production.

Example:
Imagine you are working on an e-commerce website with a team of developers. Each time a developer pushes code to the Git repository, AWS CodeBuild picks up the changes, runs tests, and notifies the team if something breaks. This ensures that new features are continuously integrated into the project without waiting for manual intervention.

Additional Explanations

(Q: What does “scaling automatically” mean for AWS CodeBuild?)
Scaling automatically means that AWS CodeBuild will adjust the resources it uses based on the number of builds you’re running. If there’s a high volume of builds happening at once, AWS CodeBuild will allocate more resources to handle them. You don’t need to worry about adding servers or configuring resources — it does it automatically.

Example AWS CodeBuild Workflow

Let’s break down an example workflow of how CodeBuild operates when you push your code to a repository:

1. Source Code is Pushed to a Repository
   This could be GitHub, AWS CodeCommit, or any other source that AWS CodeBuild supports.

2. CodeBuild Retrieves the Code
   CodeBuild fetches the latest changes to your repository.

3. CodeBuild Runs the Build Process
   CodeBuild executes a series of build commands as specified in the buildspec.yml file (explained in a later section). These commands include installing dependencies, running tests, and creating artifacts.

4. Build Results are Provided
   After the build is complete, CodeBuild provides logs and status updates. If the build fails, you can see detailed error messages to help troubleshoot.

Prerequisites and Setup

Account Setup

Before you can use AWS CodeBuild, you need to have an AWS account and set up the necessary permissions. Here’s what you need to do:

1. AWS Account Registration
If you don’t already have an AWS account, you need to sign up for one.

• Go to the AWS Registration Page
• Fill out the necessary information such as name, email address, and payment details.
• Create a new AWS account. AWS offers a free tier for new users, which provides limited resources for free.

(Q: Why do I need an AWS account?)
An AWS account allows you to access AWS services like CodeBuild, S3, EC2, and many others. You’ll need this account to set up and use AWS CodeBuild, as it is part of AWS’s suite of cloud services.

2. Setting Up IAM Roles and Permissions for CodeBuild
To interact with AWS CodeBuild, you must set up IAM (Identity and Access Management) roles. These roles define what actions can be performed by users or services, such as CodeBuild, in your AWS account.

• Create an IAM Role: This role will allow CodeBuild to access other AWS services like S3 (for storing build artifacts) and CloudWatch (for logs).
• Grant the Necessary Permissions: You will need to attach the right permissions to the IAM role, ensuring CodeBuild can perform tasks like accessing repositories or storing build output.

Steps to Create an IAM Role for CodeBuild:

1. Open the IAM Console in AWS Management Console.
2. Click on “Roles”, then “Create Role”.
3. Select “CodeBuild” as the trusted entity (this will allow CodeBuild to use the role).
4. Attach Policies such as AWSCodeBuildDeveloperAccess, which provides necessary permissions to CodeBuild.
5. Complete the setup by giving the role a name and saving it.

(Q: Why do I need IAM roles for CodeBuild?)
IAM roles are required to ensure security. They grant the necessary permissions to services like CodeBuild, so it can access your AWS resources securely. For example, without the correct role, CodeBuild wouldn’t be able to access your source code or store the build results.

Example:
Consider IAM roles like keys to a locked door. If you want CodeBuild to access your S3 bucket (like a storage room), you need to give it the correct key (IAM role) that unlocks that door. Without the right permissions, CodeBuild won’t be able to get in and retrieve or store anything.

Setting Up AWS CodeBuild for the First Time

Once your AWS account and IAM roles are set up, you can move on to setting up CodeBuild for the first time. Here’s a step-by-step guide:

1. Step-by-Step Guide to Creating a CodeBuild Project

A “project” in CodeBuild is where you define the settings for your builds — what source code to build, what environment to use, and where to store the build artifacts.

Steps to Create a CodeBuild Project:

1. Go to the AWS CodeBuild Console
   Navigate to the AWS CodeBuild Console.

2. Click “Create Project”
   You’ll be prompted to configure your project with the following settings:

   • Project Name: Enter a name for your project (e.g., MyNodeAppBuild).
   • Source: Choose the repository where your code resides (e.g., AWS CodeCommit, GitHub, or Bitbucket) and the branch you want to build.
   • Environment: Select the build environment (you can use AWS’s managed environments or specify a custom Docker image).

3. Configure Buildspec File
   The buildspec.yml file tells CodeBuild how to build and test your code. You can either include this file in your source code or define the build commands directly in the console.

4. Set Up Artifacts
   Artifacts are the output of the build process (e.g., the compiled software). You can configure where you want the artifacts to be stored — usually in an S3 bucket.

5. Create the Project
   Click “Create Project” to finish the setup. Now, CodeBuild will be ready to build your project.

(Q: What does “buildspec.yml” mean, and why is it important?)
The buildspec.yml file is a YAML file that defines the build commands and phases for your project. It’s like a recipe that tells CodeBuild what steps to follow to compile, test, and package your software.

Example:
If you’re baking a cake, you follow a recipe that tells you what ingredients to use and the order in which to mix them. Similarly, the buildspec.yml file tells CodeBuild the steps to take, like “install dependencies”, “run tests”, and “deploy to S3”.

(Q: How do I monitor my build’s progress in AWS CodeBuild?)
You can monitor the status of your builds directly from the AWS Management Console. Once a build starts, you can view real-time logs, check for errors, and even download build artifacts if needed.

Example:
Imagine you’ve just sent your car for a service. You want to track its progress — whether it’s being repaired or still under inspection. Similarly, with AWS CodeBuild, you can track the progress of your builds through the dashboard and view detailed logs for any errors.

Summary of the Prerequisites and Setup Process:

1. Sign up for an AWS account to access AWS services.
2. Set up IAM roles to securely allow CodeBuild to interact with other AWS services.
3. Create your CodeBuild project, specifying the source, build environment, and build commands.
4. Monitor your builds using the AWS Management Console.

By following these steps, you’ll have AWS CodeBuild ready to automate your build processes securely and efficiently.

How AWS CodeBuild Works

In this section, we’ll walk through the core workings of AWS CodeBuild, covering the entire build process, from source code retrieval to the generation of build artifacts. We’ll also dive into the important buildspec.yml file and break down its components so you can easily grasp how to customize your builds.

Basic Workflow

AWS CodeBuild automates the process of building and testing your code. Let’s break it down into simpler steps.

1. CodeCommit / GitHub Integration
CodeBuild can integrate with various source repositories like AWS CodeCommit, GitHub, Bitbucket, etc. When you create a CodeBuild project, you specify where your source code resides. CodeBuild will automatically fetch the latest version of your code every time a build is triggered.

(Q: What is CodeCommit, and why would I use it instead of GitHub?)
AWS CodeCommit is a fully managed version control service that works like GitHub. It helps you store and manage your source code securely on AWS. You might prefer CodeCommit over GitHub if you’re already using AWS for your infrastructure and want everything in one place. However, GitHub is more popular for open-source projects and has better collaboration tools.

Example:
If you’re building a project with a team, CodeBuild will automatically get the latest version of the code from GitHub or CodeCommit whenever a change is made, ensuring that your build process is always based on the most recent code.

2. Source Code Retrieval
After you set up your repository, CodeBuild fetches the latest code every time a new build is triggered. CodeBuild uses the repository’s connection details (e.g., GitHub authentication tokens) to access the code.

(Q: What happens if the source code repository is private?)
If your repository is private, CodeBuild will need permissions to access it. In this case, you’ll need to set up authentication via OAuth or personal access tokens (for GitHub) or AWS credentials (for CodeCommit).

Example:
Imagine you are at a library and need a specific book. You show your membership card (authentication), and the librarian gives you the book (code) you’re looking for. Similarly, CodeBuild uses authentication credentials to access your code from the source repository.

3. Build Process
Once the code is fetched, CodeBuild starts the build process. During this phase, CodeBuild runs a series of commands that are typically specified in a buildspec.yml file. This can include installing dependencies, running tests, and compiling the source code.

(Q: What does “build” mean in software development?)
In software development, “building” is the process of turning your source code into a working application. This usually includes compiling the code, installing any required libraries, and performing tests to ensure the software works as expected.

Example:
If you’re assembling a piece of furniture, “building” it would involve following the instructions to put together the pieces (source code) into a finished product (working application). Similarly, CodeBuild assembles your code and runs tests to ensure everything is functioning correctly.

4. Artifacts and Output
After the build process is complete, the output is saved as “artifacts.” These are the final files produced by the build (e.g., compiled code, deployment packages, or Docker images). CodeBuild stores these artifacts in a location you specify, like an S3 bucket.

(Q: Why are artifacts important?)
Artifacts are the result of your build process. They are the files you use to deploy your application to servers, or sometimes to run additional tests. Without artifacts, your build wouldn’t produce usable results.

Example:
Think of an artifact like a finished cake after baking. The cake (artifact) is the end product of your effort (build), and it’s what you present to the customer (deploy). Without the cake, you don’t have a final product to serve.

Understanding Build Specifications (buildspec.yml)

Now that you know the basic workflow, it’s time to dive into one of the most crucial parts of AWS CodeBuild: the buildspec.yml file. This file is essential because it defines how the build should happen. It tells CodeBuild what to do step-by-step.

1. What is buildspec.yml?
The buildspec.yml file is a YAML file that provides instructions for the build process. It specifies the phases of the build, what commands to run, where to store build output, and more.

(Q: Why do I need a buildspec.yml file?)
This file is the backbone of your build process. Without it, CodeBuild wouldn’t know what steps to take during the build process. It’s like a recipe for baking a cake — it tells CodeBuild exactly how to assemble your application.

Example:
Imagine you’re a chef, and you want to bake a cake. You would follow a recipe that tells you which ingredients to use, in what order, and at what temperature. Similarly, buildspec.yml provides the “recipe” for your code build process.

2. Key Components of buildspec.yml
The buildspec.yml file is structured in phases, each performing different tasks during the build process. The main components include:

• version: Specifies the version of the buildspec file format (usually 0.2).
• phases: Defines the various build stages like install, build, and post_build.
• artifacts: Specifies the output files of the build and where they should be stored (e.g., in an S3 bucket).
• env: (Optional) Defines environment variables to use during the build process.

3. Example of a Simple buildspec.yml File

Let’s look at a basic example of a buildspec.yml file and break it down:

version: 0.2

phases:
  install:
    runtime-versions:
      java: node:18
    commands:
      - echo Installing dependencies...
      - npm install

  build:
    commands:
      - echo Building the application...
      - npm run build

  post_build:
    commands:
      - echo Build completed. Preparing artifacts...

artifacts:
  files:
    - build/**/* # This specifies which files to store as build artifacts

env:
  variables:
    MY_ENV_VAR: "Production"

(Q: What does each part of this buildspec.yml file do?)

• version: 0.2 specifies the version of the buildspec.yml format.
• install: This phase installs the necessary dependencies (e.g., Node.js dependencies) before starting the build.
• build: In this phase, CodeBuild runs the command npm run build to actually build your application.
• post_build: After the build is completed, any additional steps (like preparing artifacts) are executed.
• artifacts: This section specifies which files should be saved after the build is completed — in this case, everything in the build/ directory.
• env: This is where you can set environment variables to be used during the build process.

Example:
The buildspec.yml file is like a step-by-step instruction manual for assembling furniture. Each step (installing dependencies, building the app, and packaging the output) is clearly defined. If the instructions aren’t followed correctly, the final product (your application) may not work properly.

Summary:

1. CodeBuild Workflow: CodeBuild pulls the latest code from your repository, runs the build process (including installation, building, and testing), and stores the output as artifacts.
2. buildspec.yml: This file tells CodeBuild exactly what commands to run at each step of the process, making your build repeatable and customizable.

By understanding the basic workflow of AWS CodeBuild and the purpose of the buildspec.yml file, you can customize your builds and automate your development lifecycle more efficiently.

Configuring Your First Build Project

Setting up a build project in AWS CodeBuild is essential for automating your development pipeline. In this section, we’ll guide you through the process of creating and configuring your first CodeBuild project, using both the AWS Console and AWS CLI. We’ll also cover how to set up your source repositories, output artifacts, and the build environment.

Creating a Build Project in AWS CodeBuild

First, let’s understand how to create a build project, which is a configuration that tells CodeBuild what code to build and how to build it.

Using AWS Console

The easiest way to get started is by using the AWS Console, which is the graphical user interface (GUI) for managing AWS services.

Steps to create a build project in the AWS Console:

1. Go to the AWS CodeBuild Console.
2. Click on Create build project.
3. Fill in the required details:
   • Project name: Give your project a unique name.
   • Source provider: Select your source repository, e.g., GitHub, AWS CodeCommit, or Amazon S3.
   • Environment: Choose the environment that will run the build (we’ll cover this in more detail later).
   • Buildspec: Specify whether you want to use a buildspec.yml file or provide custom commands.
4. Review your configuration and click Create project.

(Q: What does creating a build project mean?)
Creating a build project is like setting up a blueprint for your code. Just like you need a plan to build a house, you need a project to tell CodeBuild how to run your build.

Example:
In the console, when you select GitHub as the source, you’re essentially telling AWS to connect to your GitHub repository and fetch the latest version of the code every time the build is triggered.

Using AWS CLI / SDK

If you prefer to automate the creation process using scripts, you can also create a build project via the AWS CLI or SDKs. Here’s how you would do it with the AWS CLI:

Command to create a project:

aws codebuild create-project \
    --name MyBuildProject \
    --source type=GITHUB,location=https://github.com/username/repository \
    --artifacts type=S3,location=my-artifact-bucket \
    --environment type=LINUX_CONTAINER, image=aws/codebuild/standard:5.0 \
    --service-role arn:aws:iam::123456789012:role/service-role/my-codebuild-role

(Q: What does this command do?)
This command creates a build project called MyBuildProject that uses a GitHub repository as the source, stores the output in an S3 bucket, uses a pre-built AWS Linux container as the environment, and assigns an IAM role for permissions.

• --name MyBuildProject: Specifies the name of the project.
• --source type=GITHUB: Points to your source repository (GitHub in this case).
• --artifacts type=S3: Specifies where to store the build output (S3 bucket).
• --environment: Defines the build environment (AWS managed container).
• --service-role: Specifies the IAM role CodeBuild should use for permissions.

Setting Source and Artifacts

Now, let’s dive into how you specify where your code comes from and where to store the output.

Specifying Source Repositories (GitHub, S3, CodeCommit)

You need to tell CodeBuild where to pull your source code from. AWS supports several repositories:

1. GitHub: Popular for open-source projects and collaboration.
2. Amazon S3: Useful when your source code is stored as zip files in an S3 bucket.
3. AWS CodeCommit: AWS’s own Git-based repository service.

(Q: What if I want to use a private GitHub repository?)
For private repositories, you need to authenticate AWS CodeBuild with GitHub using a personal access token or OAuth.

Example:
If your source is GitHub, AWS will ask for your repository URL like https://github.com/username/repository. This way, every time a build is triggered, CodeBuild will fetch the latest version of the code from GitHub.

Defining Output Artifacts

Artifacts are the files generated by the build process. For instance, this could be a compiled application or a Docker image.

You can specify where to store these artifacts, typically in an S3 bucket. Here’s how you define the artifacts in the AWS Console or buildspec.yml.

Example in AWS Console:
When setting up the build project, you can choose S3 as the destination for your artifacts and specify the S3 bucket name.

Example in buildspec.yml:

artifacts:
  files:
    - "**/*" # Store all files produced by the build
    - "!**/*.md" # Exclude markdown files
  discard-paths: yes # Do not retain folder structure
  base-directory: build/ # Store only files inside the build directory

(Q: What happens if I don’t specify artifacts?)
If you don’t specify output artifacts, CodeBuild will only run the build but won’t store the results anywhere, which means you can’t use the build output later for deployment or testing.

Build Environment Configuration

Now let’s configure the environment where your build will run. You have two main options: managed images and custom images.

Choosing a Build Image (Managed vs Custom)

1. Managed Images:
   AWS provides pre-configured environments with popular tools like Java, Node.js, Python, etc. These environments are easy to set up and require minimal configuration.

   Example:
   If you’re building a Node.js application, you can select aws/codebuild/standard:5.0, which comes with Node.js pre-installed.

2. Custom Images:
   If you need specific software or configurations that AWS’s managed images don’t support, you can create your own Docker container and use it as the build environment.

(Q: Why should I use a custom image?)
Use a custom image if your project requires specific software versions, libraries, or configurations not available in AWS’s managed images.

Example of using a custom image:
Suppose your build process requires a specific version of Java, not available in the default AWS CodeBuild image. You can create a custom Docker image that has the exact Java version you need, and specify it in the build configuration.

Environment Variables

Environment variables allow you to store values that can be accessed by your build commands. These can be useful for storing configuration values, secrets, or system paths that the build might need.

Example:
You might want to set the environment variable DATABASE_URL to connect your application to a database during the build process.

Command example:
In the AWS Console, you can set environment variables under the Environment section of your build project. You can also define them in your buildspec.yml like this:

env:
  variables:
    DATABASE_URL: "jdbc:mysql://localhost:3306/mydb"

(Q: What if I need to set a secret environment variable?)
For sensitive data (like API keys), you should use AWS Secrets Manager to store these values securely and inject them into the build environment using environment variables.

Summary:

1. Creating a Build Project: You can create a build project either through the AWS Console or AWS CLI. This project specifies your source code repository, build environment, and output artifacts.
2. Source Repositories: CodeBuild supports GitHub, S3, and CodeCommit as sources for your code.
3. Output Artifacts: The output of your build (like compiled code) is stored as artifacts, typically in S3.
4. Build Environment: You can choose between AWS-managed environments or custom Docker images, depending on your project’s requirements.
5. Environment Variables: Use environment variables to store configuration data or secrets that your build process might need.

By following these steps and configurations, you’ll be able to set up your first AWS CodeBuild project efficiently, whether through the Console or CLI.