The purpose of this repository is to represent current state of apps (versions, configs, etc.) in all environments.
The main concept is to store the state in a single place (for all environments) and perform releases and promotions using git. This methodology is often referred to as GitOps.
In our PoC we used GoCD as a CD platform that continously monitors this repository and updates all environments to always reflect the state stored in this repository for all registered applications. This also includes adding apps to and removing apps from any environment.
Our proof of concept uses one central installation of GoCD that manages all environments.
GoCD uses this repository in "Config Repository" setting to continously monitor changes and sync pipelines definitions using **/*.gocd.yaml filter pattern. By doing so we can quickly make changes to the pipelines, add new ones (for testing) or revert changes when needed. We can also restore GoCD state in case of failures quickly using this repo.
Pipelines are also grouped by app name and environment so one can quickly find in GoCD's UI what versions of a given app is deployed in all environments and also find all apps that reached production environment stage.
Environments are defined in environments.gocd.yaml. One can define environment variables specific for a given environment that will be made available to all pipelines bound to a given environment (i.e. for making helm releases one could specify kube context ID).
These variables can be overriden inside pipeline definitions if needed.
Adding new environments requires adding an entry in environments.gocd.yaml file and creating pipeline definition files for all apps targeted for that environment.
Also pipelines are configured to monitor (by polling) this repository for changes at paths specific for a given environment and app.
I.e. when changing, adding or removing a file under app1/ folder only a single pipeline for a specific environment of the application app1 will be triggered. Which environment pipeline will be triggered is determined by one of the following file name patterns:
app1/<environment>.*app1/<environment>-*app1/<environment>_*app1/<environment>/*
- Automate adding new apps by using a templates from
_templates/subdirectory. - Change pipelines so they do something useful (helm release) instead of echo.
- Declare other materials for apps (ECR repo, docker image tag, git repo with the apps source code).
- Add notifications mechanism so dev teams get notified when GoCD pipeline is completed (with success or failure).