Terraform Hetzner Cloud K3S

🎯 About

Get a cheap HA-ready Kubernetes cluster in less than 5 minutes, with easy configuration setup through simple Terraform variables, 💯 GitOps way !

This opinionated Terraform template will generate a ready-to-go cloud infrastructure through Hetzner Cloud provider, optimized for MicroOS, with preinstalled K3S, the most popular lightweight Kubernetes distribution.

Heavily inspired by Kube-Hetzner, but largely simplified by excluding all custom helm installs that I prefer to manage externally. It doesn't use any local/remote exec provisioners, only cloud-init, so quicker to set up, and Powershell compatible.

For people that need a lightweight container orchestrator, the Swarm provider should be a better fit.

🚀 Quick start

A valid MicroOS snapshot, identified by the selector microos-snapshot=yes must be available in your Hetzner Cloud account. The latest snapshot will be automatically selected by default.

✅ Requirements

Before starting, you need to have :

1. A Hetzner cloud account.
2. A terraform client.
3. A hcloud client.
4. A kubectl client.

On Windows :

scoop install terraform hcloud

🏁 Starting

Prepare

The first thing to do is to prepare a new hcloud project :

1. Create a new EMPTY hcloud empty project.
2. Generate a Read/Write API token key to this new project according to this official doc.

Setup

Now it's time for initial cluster setup.

1. Copy this kube config example into a new empty directory and rename it kube.tf.
2. Execute terraform init in order to install the required module
3. Replace all variables according your own needs.
4. Finally, use terraform apply to check the plan and initiate the cluster setup.

Topologies

Contrary to Docker Swarm which is very flexible at low prices, with many topologies possible as explained here, K8S is really thought out for HA and high horizontal scalability, with complex workloads.

For administrators

flowchart TB
ssh((SSH))
kubectl((Kubectl))
kubectl -- Port 6443 --> lb{LB}
ssh -- Port 2222 --> controller-01
lb{LB}
subgraph controller-01
  direction TB
  kube-apiserver-01([Kube API Server])
  etcd-01[(ETCD)]
  kube-apiserver-01 --> etcd-01
end
subgraph controller-02
  direction TB
  kube-apiserver-02([Kube API Server])
  etcd-02[(ETCD)]
  kube-apiserver-02 --> etcd-02
end
subgraph controller-03
  direction TB
  kube-apiserver-03([Kube API Server])
  etcd-03[(ETCD)]
  kube-apiserver-03 --> etcd-03
end
lb -- Port 6443 --> controller-01
lb -- Port 6443 --> controller-02
lb -- Port 6443 --> controller-03

Loading

For clients

flowchart TB
client((Client))
client -- Port 80 + 443 --> lb{LB}
lb{LB}
lb -- Port 80 --> worker-01
lb -- Port 80 --> worker-02
lb -- Port 80 --> worker-03
subgraph worker-01
  direction TB
  traefik-01{Traefik}
  app-01([My App replica 1])
  traefik-01 --> app-01
end
subgraph worker-02
  direction TB
  traefik-02{Traefik}
  app-02([My App replica 2])
  traefik-02 --> app-02
end
subgraph worker-03
  direction TB
  traefik-03{Traefik}
  app-03([My App replica 3])
  traefik-03 --> app-03
end
overlay(Overlay network)
worker-01 --> overlay
worker-02 --> overlay
worker-03 --> overlay
overlay --> db-rw
overlay --> db-ro
db-rw((RW SVC))
db-rw -- Port 5432 --> storage-01
db-ro((RO SVC))
db-ro -- Port 5432 --> storage-01
db-ro -- Port 5432 --> storage-02
subgraph storage-01
  pg-primary([PostgreSQL primary])
  longhorn-01[(Longhorn<br>volume)]
  pg-primary --> longhorn-01
end
subgraph storage-02
  pg-replica([PostgreSQL replica])
  longhorn-02[(Longhorn<br>volume)]
  pg-replica --> longhorn-02
end
db-streaming(Streaming replication)
storage-01 --> db-streaming
storage-02 --> db-streaming

Loading

📝 License

This project is under license from MIT. For more details, see the LICENSE file.

Made with ❤️ by Adrien Beaudouin