init k8s guide
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@ -36,7 +36,7 @@ This guide is mainly intended for any developers or some SRE who want to build a
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* Test above CI tools with a sample **.NET app**, with automatic CD using Flux
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* Integrate the app to our monitoring stack with [OpenTelemetry](https://opentelemetry.io/), and use [Tempo](https://grafana.com/oss/tempo/) for distributed tracing
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* Do some load testing scenarios with [k6](https://k6.io/)
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* Go further with [SonarQube](https://www.sonarsource.com/products/sonarqube/) for advanced code quality analysis and automatic code coverage reports
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* Go further with [SonarQube](https://www.sonarsource.com/products/sonarqube/) for Continuous Inspection on code quality, including automatic code coverage reports
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### You probably don't need Kubernetes 🪧
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@ -61,11 +61,45 @@ For more enterprise grade solution check [Teleport](https://goteleport.com/), wh
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## K3s cluster initialization with Terraform
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Let's begin with basic cluster setup 1 master associate to 3 workers nodes. In order to minimize terraform code boilerplate and K3s initial setup, we'll use [my dedicated terraform module](https://registry.terraform.io/modules/okami101/k3s).
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Let's initialize basic cluster setup with 1 master associate to 3 workers nodes. For that we'll using the official [Hetzner Cloud provider](https://registry.terraform.io/providers/hetznercloud/hcloud) for Terraform.
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{{< alert >}}
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Note as this module wants to be very lightweight and simplistic, easy customization and maximum flexibility by allowing direct usage of underline [hcloud provider](https://registry.terraform.io/providers/hetznercloud/hcloud).
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{{</ alert >}}
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However, write all terraform logic from scratch is a bit tedious, even more if including K3s initial setup, so a better approach is to use a dedicated module that will considerably reduce code boilerplate.
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For that we have mainly 2 options :
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* Using the strongest community driven module for Hetzner : [Kube Hetzner](https://registry.terraform.io/modules/kube-hetzner/kube-hetzner/hcloud/latest)
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* Write our own reusable module or using my [existing start-kit module](https://registry.terraform.io/modules/okami101/k3s)
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Here are the pros and cons of each module :
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| | [Kube Hetzner](https://registry.terraform.io/modules/kube-hetzner/kube-hetzner/hcloud/latest) | [Okami101 K3s](https://registry.terraform.io/modules/okami101/k3s) |
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| ----------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
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| **Support** | Strong community | Just intended as a reusable starter-kit |
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| **Included helms** | Traefik, Longhorn, Cert Manager, Kured | None, just the K3s initial setup, which is preferable when manage helms dependencies on separated terraform project |
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| **Hetzner integration** | Complete, use [Hcloud Controller](https://github.com/hetznercloud/hcloud-cloud-controller-manager) internally, allowing dynamic Load Balancing, autoscaling, cleaner node deletion | Basic, public Load Balancer is statically managed by the nodepool configuration, no autoscaling support |
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| **OS** | openSUSE MicroOS, optimized for container worloads | Debian 12 or Ubuntu 22.04 |
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| **Initial setup** | Require packer for initial Snapshot creation, and slower on node creation because Hetnzer don't support it natively | Just about ~2 minutes for all cluster setup |
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| **Client support** | POSIX-based OS only, require WSL on Windows | All including Powershell |
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| **Internal complexity** | Huge, you can't really put your head inside | Very accessible, easy to extend and fork, better for learning |
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| **Upgrade** | You may need to follow new versions regularly | As a simple starter-kit, no need to support all community problems, so very few updates |
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| **Quality** | Use many hacks to satisfy all community needs, plenty of remote-exec and file provisioner which is not recommended by HashiCorp themselves | Use standard **cloud-config** for initial provisioning, then **Salt** for cluster OS management |
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| **Security** | Needs an SSH private key because of local provisioners, and SSH port opened to every node | Require only public SSH key, SSH port only opened for controllers, required SSH jump from a controller to access any internal worker node |
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| **Reusability** | Vendor locked to Hetzner Cloud | Easy to adapt for a different cloud provider as long as it supports **cloud-config** (as 99% of them) |
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So for resume, choose Kube Hetzner module if :
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* You want to use an OS optimized for containers, but note as it takes more RAM usage than Debian-like distro (230 Mo VS 120Mo).
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* Strong community support is important for you
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* Need of [Hcloud Controller](https://github.com/hetznercloud/hcloud-cloud-controller-manager) functionalities from the ground up, giving support for **autoscaling** and **dynamic load balancing**
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Choose the starter-kit module if :
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* You want to use a more standard OS, as Debian or Ubuntu, which consume less RAM, managed by preinstalled Salt
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* You prefer to start with a simplistic module, without internal hacks, giving you a better understanding of the cluster setup step-by-step and more moveable to another cloud provider
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* Very quick to set up, as it doesn't require any packer image creation, and use cloud-config for initial setup
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* Preferring manage additional helm dependencies on a separated terraform project
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So for this guide, I'll use my own module, feel free to use the other one if you prefer.
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## K3s configuration and usage
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