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https://github.com/axgkl/hk3sf

Hetzner k3s functions
https://github.com/axgkl/hk3sf

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Hetzner k3s functions

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[![Tests](https://github.com/axgkl/hk3sf/actions/workflows/tests.yml/badge.svg)](https://github.com/axgkl/hk3sf/actions/workflows/tests.yml)



# Hetzner K3s Functions



> A collection of functions to setup K3s clusters on [Hetzner Cloud][hcloud], based on vitobotta's [hetzner-k3s][hk3s]



## About



[Hetzner-k3s][hk3s] is nicely engineered general k3s installation tool on Hetzner, with a large degree of declarative possibilities for customization. As terraform, it is a single static binary and idempotent, with a single source of truth. In contrast to terraform it is straightforward to use, with far less abstractions but a lot of built in best practices, incl CNI and autoscaling, plus faster.



This repo here provides a set of **bash functions**, incl. possibly useful support tools to organize them, in order to further automate _around_ the pure k3s installation, which hetzner-k3s provides.



## Not a Wrapper



❗ This repo is **not** meant to be a convenience wrapper, to get you to **your** k3s setup. Unmodified it works for me - but it won't for you. It is _neither_ meant to relief you off the effort to learn the underlying machinery, nor from adding/adjusting code, to customize!



> As nearly always, [Prime nails it](https://youtu.be/EvzB_Q1gSds?t=54).



So: **Only** if you _anyway_ would automate your cluster setup using bash scripts, you might find this useful, as a starting point.



_You **will** have to modify the functions to your needs, e.g. provide dns provisioning for **your** provider, since you won't use the [built in one](../pkg/dns.sh) (DO) and/or supply [ingress setup](../pkg/ingress.sh) functions, when **not** using nginx and so on._  

What I _did_ aim for, is to make the places _where_ to customize as canonical as possible, plus provide blueprints, for _how_ to do it.



## Features



### Pre K3s Installation



Focus is on creating the cluster with private IPs only, and a _proxy_ server in front of them:



```mermaid

flowchart LR

    A[World] --> B[Bastion Proxy
IP pub
Opt.LoadBalancer]

    B --priv net--> M1[Master 1
...
Master 3]

    B --priv net--> w1[Worker 1
...
Worker n]

    B --priv net--> a1[Autoscaled 1
...
Autoscaled n]

```



That bastion server is the only one with a public IP, and [can be equipped with a l4 loadbalancer](./docs/l4lb.md), forwarding the traffic into the cluster, like a hetzner loadbalancer would do.



💡 Using the bastion node as loadbalancer is optional. [hetzner-k3s][hk3s] does by default create hetzner loadbalancers for you, using the hetzner cloud controller manager (ccm).



[Here](./docs/l4lb.md) is a detailed description of the loadbalancer setup, incl. some reasons for it.



---



We provide the functions necessary to



- create the private network

- bastion node itself, with ssh key

- tools (hetzner-k3s, kubectl, helm) and [optional load balancer service](./docs/l4lb.md) on it

- cloud init config for hetzner-k3s, so that the priv ip nodes can reach the internet



Then hetzner-k3s can be run from there, to create the cluster.



### K3s Installation



From the proxy server, we then kick off hetzner-k3s, using a config we synthesized from the environ.



[Here](./docs/privip.md) are the details regarding a private IP only cluster setup.



### Post K3s Installation



We provide functions to



- transfer kubeconfig from the bastion to the local machine

- configure local ssh

- install cert-manager into the cluster

- install ingress-nginx into the cluster

- install services using that ingress into the cluster, in a way so that https traffic from the world can reach the application pods with

  - working certificates

  - optional pod affinity via cookie ("sticky sessions")

  - source ip preservation (using [proxy protocol](https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt))

  - autoscaling support



## Usage



In general the script provides its functions after being sourced from a bash script _you_ provide and make executable.



See the ci [../tests/setup.sh](../tests/setup.sh) script for an example, which installs the full cluster from scratch.



💡 When you pass _arguments_ to that script, this results in an execution of the given function and exit of the script, w/o running the subsequent functions after sourcing.



General layout of your script is therefore:



```bash

CONFIGVAR1=CONFIGVAL1

...

source /main.sh "$@" # exits after execution of any given arguments in $@ (e.g. funcname, params). 

#Otherwise continues with the functions below:

setup_function1

setup_function2

...

```



`yourscript -h` lists all available functions.



## CI Automation



See [here](./docs/ci.md)



## Customization



See [here](./docs/customization.md)



## Dev Details



[here](./docs/customization.md)



---



## Refs



- [notes](./docs/knowledge.md)



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---



K3s with: HA + AutoScaling + GitOps from scratch. 💗 For < 20€/month if wanted.



[hk3s]: https://github.com/vitobotta/hetzner-k3s

[hcloud]: https://docs.hetzner.cloud/