Building on the prior article of Fedora CoreOS + Ansible => K8s we want complete Infrastructure As Code. The newest way of doing this is GitOps where nearly everything is controlled by SCM. For that, flux is one of my favorites but Argo will also work.
The benefit of GitOps and K8s is that developers can have complete but indirect access to various environments. This makes it really easy for a DevOps team to provision the tooling very easily to either spin up environments effortlessly or let the developers do it themselves. That helps us get close to Platform Engineering.
Flux GitOps Repo
For this article, this is the tagged version of the GitOps repo used. At its core, we manually generated the yaml manifests via scripts commands. Namely upgrade_cluster1.sh and generate_cluster1.sh. Combined these create the yaml manifests needed. Upgrade cluster can be run to refresh the yaml during an upgrade but do not let it trick you. It can also be used to generate the initial component yaml. The generate_cluster1.sh should only need to be run once.
The flux cli has a bootstrap command that can be used but for this, we want disposable K8s clusters that can be torn down and then new ones rebuilt and attached to the same repo. Not only does this allow the workloads running to be treated like cattle but also the infrastructure itself.
To achieve this, we are manually creating the yaml manifests (still using the supported CLI tools) but decoupling that from the initial setup, deploy and running of the environment.
What Did We Get?
From a simple set of changes to pull and deploy flux, we have a sample ingress controller (nginx). In it you can specify any parameter about it and have clear visibility as to what is deployed. In this scenario we are just specifying the version but we could also specify how many instances or whether to deploy via daemonset (one instance per worker node).
Wrapping It All Up – What Is The Big Deal?
It might be a natural question as to what is the big deal about K8s, IaC, GitOps and this entire ecosystem. True IaC combined with GitOps allows complete transparency into what is deployed into production because flux ensures what is in Git is reconciled with the configured cluster. No more, one off configurations that nobody knows about until upgrade to replacement time on the server.
The fact that we have so much automation allows for tearing down and rebuilding as necessary. This allows for easy patching. Instead of applying updates and hoping for the best, just instantiate new instances and tear down the old ones.