166 lines
6 KiB
Markdown
166 lines
6 KiB
Markdown
+++
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title = "Building k3s on a Pi"
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author = ["Elia el Lazkani"]
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date = 2020-08-09
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lastmod = 2020-08-09
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tags = ["arm", "kubernetes"]
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categories = ["k3s"]
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draft = false
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+++
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I have had a **Pi** laying around used for a simple task for a while now.
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A few days ago, I was browsing the web, learning more about privacy, when I stumbled upon [AdGuard Home](https://adguard.com/en/welcome.html).
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I have been using it as my internal DNS on top of the security and privacy layers I add to my machine.
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Its benefits can be argued but it is a DNS after all and I wanted to see what else it can do for me.
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Anyway, I digress. I searched to see if I could find a container for **AdGuard Home** and I did.
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At this point, I started thinking about what I could do to make the [Pi](https://www.raspberrypi.org/) more useful.
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That's when [k3s](https://k3s.io/) came into the picture.
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<!--more-->
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## Pre-requisites {#pre-requisites}
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As this is not a **Pi** tutorial, I am going to be assuming that you have a _Raspberry Pi_ with **Raspberry Pi OS** _Buster_ installed on it.
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The assumption does not mean you cannot install any other OS on the Pi and run this setup.
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It only means that I have tested this on _Buster_ and that your milage will vary.
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## Prepare the Pi {#prepare-the-pi}
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Now that you have _Buster_ already installed, let's go ahead and [fix](https://rancher.com/docs/k3s/latest/en/advanced/#enabling-legacy-iptables-on-raspbian-buster) a small default configuration issue with it.
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**K3s** uses `iptables` to route things around correctly. _Buster_ uses `nftables` by default, let's switch it to `iptables`.
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```text
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$ sudo iptables -F
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$ sudo update-alternatives --set iptables /usr/sbin/iptables-legacy
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$ sudo update-alternatives --set ip6tables /usr/sbin/ip6tables-legacy
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$ sudo reboot
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```
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At this point, your _Pi_ should reboot. Your **OS** is configured for the next step.
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## Pre-install Configuration {#pre-install-configuration}
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After testing **k3s** a few times, I found out that by _default_ it will deploy a few extra services like [Traefik](https://docs.traefik.io/).
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Unfortunately, just like anything the _default_ configuration is just that. It's plain and not very useful from the start. You will need to tweak it.
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This step could be done either _post_ or _pre_ deploy. Figuring out the _pre-deploy_ is a bit more involving but a bit more fun as well.
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The first thing you need to know is that the normal behavior of **k3s** is to deploy anything found in `/var/lib/rancher/k3s/server/manifests/`.
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So a good first step is, of course, to proceed with creating that.
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```text
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$ mkdir -p /var/lib/rancher/k3s/server/manifests/
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```
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The other thing to know is that **k3s** can deploy _Helm Charts_.
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It will create the _manifests_ it will deploy by default, before beginning the setup, in the manifest path I mentioned.
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If you would like to see what it deployed and how, visit that path after **k3s** runs.
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I did, and I took their configuration of **Traefik** which I was unhappy with its _defaults_.
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My next step was securing the _defaults_ as much as possible and I found out that **Traefik** can do [basic authentication](https://docs.traefik.io/v2.0/middlewares/basicauth/).
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As a starting point, that's great. Let's create the credentials.
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```text
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$ htpasswd -c ./auth myUser
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```
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That was easy so far. Let's turn up the notch and create the manifest for **k3s**.
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Create `traefik.yaml` in `/var/lib/rancher/k3s/server/manifests/` with the following content.
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```yaml
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---
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apiVersion: helm.cattle.io/v1
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kind: HelmChart
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metadata:
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name: traefik
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namespace: kube-system
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spec:
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chart: https://%{KUBERNETES_API}%/static/charts/traefik-1.81.0.tgz
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valuesContent: |-
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rbac:
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enabled: true
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ssl:
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enabled: true
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dashboard:
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enabled: true
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domain: traefik-ui.example.com
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auth:
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basic:
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myUser: $ars3$4A5tdstr$trSDDa4467Tsa54sTs.
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metrics:
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prometheus:
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enabled: false
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kubernetes:
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ingressEndpoint:
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useDefaultPublishedService: true
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image: "rancher/library-traefik"
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tolerations:
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- key: "CriticalAddonsOnly"
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operator: "Exists"
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- key: "node-role.kubernetes.io/master"
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operator: "Exists"
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effect: "NoSchedule"
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```
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It's a **Pi**, I don't need prometheus so I disabled it.
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I also enabled the dashboard and added the credentials we created in the previous step.
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Now, the _Helm Chart_ will deploy an ingress and expose the dashboard for you on the value of `domain`.
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<div class="admonition note">
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<p class="admonition-title">Note</p>
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I figured out the values to set in `valuesContent` by reading the _Helm Chart_
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</div>
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## K3s {#k3s}
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If everything is in place, you are ready to proceed.
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You can install **k3s**, now, but before I get to that step, I will say a few things about **k3s**.
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**K3s** has a smaller feature set than **k8s**, hence the smaller footprint.
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Read the documentation to see if you need any of the missing features.
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The second thing to mention is that **k3s** is a one binary deploy that uses **containerd**.
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That's why we will use the script installation method as it adds the necessary **systemd** configuration for us.
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It is a nice gesture.
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Let's do that, shall we ?
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```text
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$ curl -sfL https://get.k3s.io | sh -s - --no-deploy traefik
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```
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<div class="admonition note">
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<p class="admonition-title">Note</p>
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We need to make sure that **k3s** does not deploy its own **traefik** but ours.
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Make sure to add `--no-deploy traefik` to our deployment command.
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</div>
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Point `traefik.example.com` to your **Pi** `IP` in `/etc/hosts` on your machine.
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```text
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traefik.example.com 192.168.0.5
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```
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When the installation command is done, you should be able to visit [http://traefik.example.com/](http://traefik.example.com/)
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You can get the _kubeconfig_ from the _Raspberry Pi_, you can find it in `/etc/rancher/k3s/k3s.yaml`. You will need to change the `server` **IP**.
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## Conclusion {#conclusion}
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If you've made it so far, you should have a **k3s** cluster running on a single _Raspberry Pi_.
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The next steps you might want to look into is disable the _metrics_ server and use the resources for other things.
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