Let's sketch an architecture diagram of a solution, and describe a CI/CD pipeline, including build, test, pre-deployment and post-deployment actions, and tools that could be used to deploy this application to AWS.
Solution
One approach is to add GitHub Actions to a blog-starter repository that contains the Node.js application source code, to define a CI/CD pipeline. We could re-deploy the blog-starter application onto an AWS EC2 Linux instance when source code changes are pushed to the GitHub repository. In this approach, AWS CodeDeploy services are integrated with GitHub and leveraged for this purpose.
High Level Flow
- Developer pushes a commit to a branch in the blog-starter GitHub repo.
- The push triggers GitHub actions that run AWS CodeDeploy
- The AWS CodeDeploy commands deploy the new commit to the EC2 instance that hosts the Node.js app
- Hook scripts are invoked to run pre-installation, post-installation, and application start tasks.
Architecture Sketch
Pipeline Stages
A. Test
Code quality tests can be implemented as GitHub pre-merge checks to run against the application source code. A GitHub pull request catches when a specific line in a commit causes a check to fail. This will display failure, warning, or notice next to the relevant code in the Files tab of the pull request.
The idea here is to prevent a merge to the master branch until all code quality issues have been resolved.
B. Pre-Deployment
Any dependencies that need to be installed on the Linux EC2 instance can be installed by a hook script that is defined in the CodeDeploy AppSpec file's hooks section.
The CodeDeploy AppSpec file is placed in the blog-starter repository where the AWS CodeDeploy Agent can read it, for example under blog-starter/appspec.yml.
C. Build
The blog-starter node application is built by running npm. This step is accomplished by another hook script that is defined in the CodeDeploy AppSpec file hooks section under ApplicationStart.
D. Post-Deployment
Tasks that run after the application is installed, such as changing permissions on directories or log files, can also be defined in a hook script in the CodeDeploy AppSpec file under AfterInstall.
AWS EC2 Instance
To host the application in AWS, an EC2 Linux instance can be defined and launched. Initial installation of node, npm, as well as the app by cloning the GitHub repository, can be done manually from the EC2 command-line to have these features up and running in the cloud.
AWS CodeDeploy Agent
The installer for CodeDeploy agent can be downloaded onto the EC2 Linux instance from the command line to install, and then the agent can be started as a service.
AWS CodeDeploy
Additional configuration is needed, for example, to create an AWS IAM Role and User that is authorized to run deployment commands through the CodeDeploy agent.
GitHub Actions
A deploy.yml file can be added under .github/workflows that defines the CI/CD pipeline steps, or what do to after a push. For example, 1) checkout a branch and then 2) run a CodeDeploy deployment command.
Further Reading
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