163 lines
6.3 KiB
Org Mode
163 lines
6.3 KiB
Org Mode
#+BEGIN_COMMENT
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.. title: Building k3s on a Pi
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.. date: 2020-08-09
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.. slug: building-k3s-on-a-pi
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.. updated: 2020-08-09
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.. status: published
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.. tags: kubernetes, k3s, arm
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.. category: k3s
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.. authors: Elia el Lazkani
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.. description: I have decided to make a better use of my pi, k3s came next.
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.. type: text
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#+END_COMMENT
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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 [[https://adguard.com/en/welcome.html][AdGuard Home]].
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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 [[https://www.raspberrypi.org/][Pi]] more useful.
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That's when [[https://k3s.io/][k3s]] came into the picture.
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{{{TEASER_END}}}
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* 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
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Now that you have /Buster/ already installed, let's go ahead and [[https://rancher.com/docs/k3s/latest/en/advanced/#enabling-legacy-iptables-on-raspbian-buster][fix]] 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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#+BEGIN_EXAMPLE
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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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#+END_EXAMPLE
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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
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After testing *k3s* a few times, I found out that by /default/ it will deploy a few extra services like [[https://docs.traefik.io/][Traefik]].
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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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#+BEGIN_EXAMPLE
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$ mkdir -p /var/lib/rancher/k3s/server/manifests/
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#+END_EXAMPLE
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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 [[https://docs.traefik.io/v2.0/middlewares/basicauth/][basic authentication]].
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As a starting point, that's great. Let's create the credentials.
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#+BEGIN_EXAMPLE
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$ htpasswd -c ./auth myUser
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#+END_EXAMPLE
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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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#+BEGIN_SRC 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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#+END_SRC
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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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#+BEGIN_EXPORT html
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<div class="admonition note">
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<p class="admonition-title">Note</p>
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#+END_EXPORT
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I figured out the values to set in =valuesContent= by reading the /Helm Chart/
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#+BEGIN_EXPORT html
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</div>
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#+END_EXPORT
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* 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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#+BEGIN_EXAMPLE
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$ curl -sfL https://get.k3s.io | sh -s - --no-deploy traefik
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#+END_EXAMPLE
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#+BEGIN_EXPORT html
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<div class="admonition note">
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<p class="admonition-title">Note</p>
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#+END_EXPORT
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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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#+BEGIN_EXPORT html
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</div>
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#+END_EXPORT
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Point =traefik.example.com= to your *Pi* =IP= in =/etc/hosts= on your machine.
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#+BEGIN_EXAMPLE
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traefik.example.com 192.168.0.5
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#+END_EXAMPLE
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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
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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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