Implement a Trunk branching strategy for multi-account DevOps environments

Created by Mike Stephens (AWS) and Rayjan Wilson (AWS)

Summary

When managing a source code repository, different branching strategies affect the software development and release processes that development teams use. Examples of common branching strategies include Trunk, GitHub Flow, and Gitflow. These strategies use different branches, and the activities performed in each environment are different. Organizations that are implementing DevOps processes would benefit from a visual guide to help them understand the differences between these branching strategies. Using this visual in your organization helps development teams align their work and follow organizational standards. This pattern provides this visual and describes the process of implementing a Trunk branching strategy in your organization.

This pattern is part of a documentation series about choosing and implementing DevOps branching strategies for organizations with multiple AWS accounts. This series is designed to help you apply the correct strategy and best practices from the outset, to streamline your experience in the cloud. Trunk is just one possible branching strategy that your organization can use. This documentation series also covers GitHub Flow and Gitflow branching models. If you haven't done so already, we recommend that you review Choosing a Git branching strategy for multi-account DevOps environments prior to implementing the guidance in this pattern. Please use due diligence to choose the right branching strategy for your organization.

This guide provides a diagram that shows how an organization might implement the Trunk strategy. It is recommended that you review the official AWS Well-Architected DevOps Guidance to review best practices. This pattern includes recommended tasks, steps, and restrictions for each step in the DevOps process.

Prerequisites and limitations

Prerequisites

• Git, installed. This is used as a  source code repository tool.

• Draw.io, installed. This application is used to view and edit the diagram.

Architecture

Target architecture

The following diagram can be used like a Punnett square (Wikipedia). You line up the branches on the vertical axis with the AWS environments on the horizontal axis to determine what actions to perform in each scenario. The numbers indicate the sequence of the actions in the workflow. This example takes you from a feature branch through deployment in production.

For more information about the AWS accounts, environments, and branches in a Trunk approach, see Choosing a Git branching strategy for multi-account DevOps environments.

Automation and scale

Continuous integration and continuous delivery (CI/CD) is the process of automating the software release lifecycle. It automates much or all of the manual processes traditionally required to get new code from an initial commit into production. A CI/CD pipeline encompasses the sandbox, development, testing, staging, and production environments. In each environment, the CI/CD pipeline provisions any infrastructure that is needed to deploy or test the code. By using CI/CD, development teams can make changes to code that are then automatically tested and deployed. CI/CD pipelines also provide governance and guardrails for development teams by enforcing consistency, standards, best practices, and minimal acceptance levels for feature acceptance and deployment. For more information, see Practicing Continuous Integration and Continuous Delivery on AWS.

AWS offers a suite of developer services that are designed to help you build CI/CD pipelines. For example, AWS CodePipeline is a fully managed continuous delivery service that helps you automate your release pipelines for fast and reliable application and infrastructure updates. AWS CodeBuild compiles source code, runs tests, and produces ready-to-deploy software packages. For more information, see Developer Tools on AWS.

Tools

AWS services and tools

AWS provides a suite of developer services that you can use to implement this pattern:

• AWS CodeArtifact is a highly scalable, managed artifact repository service that helps you store and share software packages for application development.

• AWS CodeBuild is a fully managed build service that helps you compile source code, run unit tests, and produce artifacts that are ready to deploy.

• AWS CodeDeploy automates deployments to Amazon Elastic Compute Cloud (Amazon EC2) or on-premises instances, AWS Lambda functions, or Amazon Elastic Container Service (Amazon ECS) services.

• AWS CodePipeline helps you quickly model and configure the different stages of a software release and automate the steps required to release software changes continuously.

Other tools

• Draw.io Desktop – An application for making flowcharts and diagrams.

• Figma is an online design tool designed for collaboration. The code repository contains templates in .fig format for Figma.

Code repository

This source file for the diagram in this pattern is available in the GitHub Git Branching Strategy for Trunk repository. It includes files in PNG, draw.io, and Figma formats. You can modify these diagrams to support your organization's processes.

Best practices

Follow the best practices and recommendations in AWS Well-Architected DevOps Guidance and Choosing a Git branching strategy for multi-account DevOps environments. These help you effectively implement Trunk-based development, foster collaboration, improve code quality, and streamline the development process.

Epics

Reviewing the Trunk workflow

Task	Description	Skills required
Review the standard Trunk process.	In the sandbox environment, the developer creates a feature branch from the main branch and uses the naming pattern feature/<ticket>_<initials>_<short description>. The developer develops code and deploys the code to the sandbox environment iteratively in order to complete the ticket. Note The developer can optionally create a sandbox branch to run an automated build or deploy pipeline in the sandbox environment. The developer creates a merge request from the feature branch into the main branch by using a squash merge. A continuous integration and continuous delivery (CI/CD) pipeline automatically builds and publishes the artifacts from the main branch to the development environment. An approver manually approves the deployment of the release artifacts to the development environment. An approver manually approves the deployment of the release artifacts to the testing environment. An approver manually approves the deployment of the release artifacts to the staging environment. An approver manually approves the deployment of the release artifacts to the production environment.	DevOps engineer

Troubleshooting

Issue	Solution
Branch conflicts	A common issue that can occur with the Trunk model is where a hotfix needs to occur in production but a corresponding change needs to occur in a feature branch, where the same resources are being modified. We recommend that you frequently merge changes from main into lower branches to avoid significant conflicts on merge to main.

Related resources

This guide doesn't include training for Git; however, there are many high-quality resources available on the internet if you need this training. We recommend that you start with the Git documentation site.

The following resources can help you with your Trunk branching journey in the AWS Cloud.

AWS DevOps guidance

• AWS DevOps Guidance

• AWS Deployment Pipeline Reference Architecture

• What is DevOps?

• DevOps resources

Trunk guidance

• Trunk Based Development

Other resources

• Twelve-factor app methodology (12factor.net)