Ampernetacle

This is a Terraform configuration to deploy a Kubernetes cluster on Oracle Cloud Infrastructure. It creates a few virtual machines and uses kubeadm to install a Kubernetes control plane on the first machine, and join the other machines as worker nodes.

By default, it deploys a 4-node cluster using ARM machines. Each machine has 1 OCPU and 6 GB of RAM, which means that the cluster fits within Oracle's (pretty generous if you ask me) free tier.

It is not meant to run production workloads, but it's great if you want to learn Kubernetes with a "real" cluster (i.e. a cluster with multiple nodes) without breaking the bank, and if you want to develop or test applications on ARM.

Getting started

Create an Oracle Cloud Infrastructure account (just follow this link).
Have installed or install kubernetes.
Have installed or install terraform.
Have installed or install OCI CLI .
Configure OCI credentials.
terraform init
terraform apply

That's it!

At the end of the terraform apply, a kubeconfig file is generated in this directory. To use your new cluster, you can do:

export KUBECONFIG=$PWD/kubeconfig
kubectl get nodes

The command above should show you 4 nodes, named node1 to node4.

You can also log into the VMs. At the end of the Terraform output you should see a command that you can use to SSH into the first VM (just copy-paste the command).

Windows

The kubeconfig.tf file currently uses UNIX-specific commands which don't work on Windows. (See #2.) I'm going to try and find a better way to get the kubeconfig file; but meanwhile, you could try to run it in WSL2. (Sorry!)

Availability Domain

If you get a message like the following:

Error: 500-InternalError
│ ...
│ Service: Core Instance
│ Error Message: Out of host capacity.

...then you can try to switch to a different availability domain. This can be done by changing the availability_domain input variable. (Thanks @uknbr for the contribution!)

Customization

Check variables.tf to see tweakable parameters. You can change the number of nodes, the size of the nodes, or switch to Intel/AMD instances if you'd like. Keep in mind that if you switch to Intel/AMD instances, you won't get advantage of the free tier.

Stopping the cluster

terraform destroy

Implementation details

This Terraform configuration:

generates an OpenSSH keypair and a kubeadm token
deploys 4 VMs using Ubuntu 20.04
uses cloud-init to install and configure everything
installs Docker and Kubernetes packages
runs kubeadm init on the first VM
runs kubeadm join on the other VMs
installs the Weave CNI plugin
transfers the kubeconfig file generated by kubeadm
patches that file to use the public IP address of the machine

Caveats

There is no cloud controller manager, which means that you cannot create services with type: LoadBalancer; or rather, if you create such services, their EXTERNAL-IP will remain <pending>.

To expose services, use NodePort.

Likewise, there is no ingress controller and no storage class.

(These might be added in a later iteration of this project.)

Remarks

Oracle Cloud also has a managed Kubernetes service called Container Engine for Kubernetes (or OKE). That service doesn't have the caveats mentioned above; however, it's not part of the free tier.

What does "Ampernetacle" mean?

It's a porte-manteau between Ampere, Kubernetes, and Oracle. It's probably not the best name in the world but it's the one we have! If you have an idea for a better name let us know. 😊

g014x/ampernetacle