This repository is a reference GitOps deployment repository containing multiple deploy environments. This example utilizes the technique of "rendered YAML branches" for GitOps deployment.

The technique of using "rendered YAML branches" removes the responsibility of config templating from Argo CD, to the CI/CD pipeline. In this example, a GitHub Action automates the config management templating (e.g. kustomize build) such that fully rendered Kubernetes manifests are outputted to an environment specific branch (e.g. env/stage, env/prod). Argo CD applications are configured to deploy the manifests from the environment branch, as opposed to a directory in the main branch.

The application source repository is located at https://github.com/akuity/guestbook and has a CI/CD Pipeline which builds new container images and automatically commits the new image tags to the kustomize environments contained in this repository.

• Easily understandable change history/diff - change is not obfuscated by config tooling
• Use different policies per environment - e.g. automated commit/deployment to dev/stage, PR approval process and protected branch for prod
• Upgrading Argo CD + baked-in toolchain (kustomize) is no longer a risk - templating done in CI, not by Argo CD
• Better security - No longer at risk from vulnerabilities in tooling (helm, kustomize)
• Safer change management - Change to a kustomize base will not immediately affect all environments
• Improved Argo CD performance - expensive templating process (kustomize build) is no longer performed by Argo CD

• Additional CI automation requirements (e.g. GitHub action)
• Does not support tools which render plain-text secrets (e.g. Kustomize + SOPS)

Environment	Status
Dev
Stage
Prod

This respository utilizes kustomize for configuration management of multiple environments. A common kustomize base is shared between all environments. Environments are organized into individual env directories, structured in the following manner:

.
├── base
│   ├── guestbook-deploy.yaml
│   ├── guestbook-ing.yaml
│   ├── guestbook-svc.yaml
│   └── kustomization.yaml
└── env
    ├── dev
    │   └── kustomization.yaml
    ├── prod
    │   └── kustomization.yaml
    └── stage
        └── kustomization.yaml

Any changes to the kustomize configuration in main branch will result in the following:

• For the env/dev and env/stage branches, the change will be automatically pushed to the environment branch resulting in immediate deployment
• For the env/prod branch, a PR will be created against the branch for manual approval

Details of how this is accomplished can be seen in the GitHub Action.

The source code for this repository is located at https://github.com/akuity/guestbook-deploy.