Tutorial: AWS Certified Developer - Associate (DVA-C02)

Branches and actions in the continuous integration and continuous delivery (CI/CD) workflow

Concepts

Before diving into branches and actions, let’s have a quick overview of CI/CD:

Continuous Integration is a development practice where developers regularly merge their code changes into a central repository, after which automated builds and tests are run.
Continuous Delivery is an extension of CI in which the software release process is automated, enabling easy and confident deployments into production at any time.

Branching Strategy

The branching strategy forms the backbone of the CI/CD workflow. It dictates how code changes flow through the version control system to the production environment. A typical strategy involves the following branches:

Main/Master: This branch contains the production-ready code. It is the source of truth for the state of the application in production.
Development: Coders merge their feature branches into the development branch. This branch contains the state of the application for the next release.
Feature Branches: These branches are created from development for working on new features or bugfixes.
Release Branches: Sometimes a separate branch is created for preparing a release. This may contain bug fixes and final polishing for a release.
Hotfix Branches: For critical issues in production, hotfix branches are created from the master branch to ensure a fast turnaround for fixes.

Here is a table comparing the roles of different branches:

Branch Type	Purpose	Merged Into
Main/Master	Serves as the code base for production.	–
Development	Collects completed features for the next release.	Main/Master
Feature	Used by developers to work on new features or fixes.	Development
Release	Prepares for a new version deployment (release candidate).	Main/Master
Hotfix	Addresses urgent production issues.	Main/Master, Development

CI/CD Actions

Actions are the tasks that run at various stages of the CI/CD pipeline. A typical pipeline might include the following actions:

Source: Triggered when a developer pushes code to a repository or when a pull request is merged.
Build: Compiles the source code into a runnable artifact, like an executable or a Docker container.
Test: Runs automated tests to verify the behavior of the code.
Deploy: Handles the pushing of the build artifact to the appropriate environment, such as staging or production.
Release: Finalizes the deployment by making the new version available to end-users.

For AWS environments, developers use AWS CodePipeline to orchestrate these actions in a CI/CD workflow. Here’s an example of how an AWS CodePipeline might be set up:

Source: AWS CodeCommit or GitHub (detects changes to the repo).
Build: AWS CodeBuild (builds the source code).
Test: AWS CodeBuild or third-party tools integrated with AWS CodePipeline (runs automated tests).
Deploy: AWS CodeDeploy (deploys the application to EC2 instances, ECS containers, or Lambda functions).
Release: Manual approval step before the changes are pushed to production.

For CI/CD workflows, version control systems play a significant role. AWS CodeCommit is an example where developers can store and version their code. Here’s a simple YAML snippet that defines a build specification for AWS CodeBuild:

version: 0.2

phases:
install:
commands:
– echo Installing dependencies…
– npm install
build:
commands:
– echo Build started on `date`
– npm run build
post_build:
commands:
– echo Build completed on `date`
artifacts:
files:
– app/build/output.jar

This YAML file tells CodeBuild how to install dependencies, build the project, and specify which files to package as build artifacts.

Summary

Understanding CI/CD branching patterns and actions ensures a developer can efficiently manage code integrations and deployments within the AWS cloud. Whether it’s for the AWS Certified Developer – Associate exam or real-world applications, mastering these workflows is essential for building and maintaining robust, scalable applications on AWS.

Answer the Questions in Comment Section

True or False: In a CI/CD workflow, it is recommended to have a separate branch for each environment such as development, testing, and production.

True
False

Answer: False

Explanation: The best practice in CI/CD is to have a common branch (like main or master) that represents the source of truth and from which all deployment activities are made. Separate branches for each environment are not typically recommended, as it can lead to complexities and integration challenges.

Which AWS service provides fully managed continuous delivery service?

AWS Lambda
AWS Batch
AWS CodeDeploy
AWS CodePipeline

Answer: AWS CodePipeline

Explanation: AWS CodePipeline is a fully managed continuous delivery service that helps you automate your release pipelines for fast and reliable application and infrastructure updates.

True or False: AWS CodeBuild can execute unit tests and generate artifacts as part of a CI/CD pipeline.

True
False

Answer: True

Explanation: AWS CodeBuild is a fully managed build service that compiles source code, runs tests, and produces software packages that are ready to deploy.

In a CI/CD pipeline, what is the purpose of the “build” stage?

To run automated tests on the produced build
To compile source code into executable programs or other runtimes
To deploy the application onto production servers
To manually review the code changes

Answer: To compile source code into executable programs or other runtimes

Explanation: The build stage in a CI/CD pipeline is where source code is compiled into executable programs or runtime packages that can be deployed to various environments.

True or False: Merge conflicts are typically resolved during the continuous deployment phase of the CI/CD pipeline.

True
False

Answer: False

Explanation: Merge conflicts are generally resolved before the deployment phase, typically during the development or integration stages when code is being merged into a shared repository or branch.

In which AWS service is the Blue/Green deployment technique supported?

AWS CodeCommit
AWS CodeBuild
AWS CodeDeploy
AWS Elastic Beanstalk

Answer: AWS CodeDeploy

Explanation: AWS CodeDeploy supports the Blue/Green deployment technique, which allows you to switch traffic between two environments with minimal downtime.

Multiple Select: Which of the following AWS services are part of the AWS suite for CI/CD?

AWS CodeCommit
AWS Glue
AWS CodePipeline
AWS CodeBuild
Amazon S3

Answers: AWS CodeCommit, AWS CodePipeline, AWS CodeBuild

Explanation: AWS CodeCommit, AWS CodePipeline, and AWS CodeBuild are part of the AWS suite designed specifically for CI/CD. AWS Glue is an ETL service and Amazon S3 is a storage service.

True or False: Rolling updates are not suitable for stateful applications that require preserving the state across deployments.

True
False

Answer: True

Explanation: Rolling updates might cause issues with stateful applications that require a consistent state because they replace the old versions with new ones incrementally. Techniques such as Blue/Green deployments may be more suitable for such applications.

Which phase in the CI/CD pipeline involves executing automated tests to validate the quality of the code?

Source phase
Build phase
Deploy phase
Test phase

Answer: Test phase

Explanation: The Test phase in a CI/CD pipeline involves running automated tests to ensure the code meets quality standards and does not introduce any known issues to the existing codebase.

True or False: In a CI/CD pipeline, only the development team is responsible for managing and executing the pipeline.

True
False

Answer: False

Explanation: In a CI/CD pipeline, multiple stakeholders, including development, operations, and sometimes QA teams, collaborate to manage and execute the pipeline. DevOps culture promotes shared responsibilities.

True or False: Amazon Elastic Container Service (Amazon ECS) supports continuous delivery through the integration with AWS CodePipeline.

True
False

Answer: True

Explanation: Amazon Elastic Container Service (Amazon ECS) can be integrated with AWS CodePipeline to allow for continuous delivery of containerized applications.

During which stage of the CI/CD pipeline would you typically configure environment variables that are specific to the deployment stage, such as API keys or database URLs?

Source stage
Build stage
Pre-deployment stage
Deployment stage

Answer: Pre-deployment stage

Explanation: Environment variables that are specific to each stage of deployment are typically configured during the Pre-deployment stage, where you set up the necessary environment and configurations before the actual deployment happens.