K8s

2024-05-04T01:00:46Z

Rtyler: update for new versions

= Alpine Linux 🌲 K8s in 10 Minutes =

== Summary ==

This guide will allow you to deploy a fresh Alpine Linux install into a Kubernetes K8 cluster in less than 10 minutes.

== Why ✨ ==

I went to learn Kubernetes recently and I built a k3 cluster using Alpine in an hour or so, it was a great experience. I figured the next step would be K8s, but I found no material on K8s for Alpine. This guide is the result of my first pass and the incorporations of high quality notes from the contributers. Kubernetes 🦄 is awesome.

== Contributers ==

* Matthew Rogers [https://github.com/RamboRogers Github] [https://www.linkedin.com/in/matthewrogerscissp/ LinkedIn]
* Mike Zolla [https://github.com/Zolla-Zolla Github] [https://www.linkedin.com/in/mike-zolla-5903b8/ LinkedIn]
* Matthew Emmett [https://github.com/mattemmett Github] [https://www.linkedin.com/in/mattemmett/ LinkedIn]

-----

= Build K8s on Alpine Linux 🌲 =

=== Prerequisites 🔍 ===

You need an [https://alpinelinux.org/ Alpine Linux] install (this guide is written against version 3.17 standard image) with internet access. I recommend at least 2 CPU with 4GB of ram and 10GB of disk for each node.

<blockquote>For HA control planes you'll need a mininum of three nodes
</blockquote>

=== 1. Setup the Repositories 📗 ===

Update you repositories under {{Path|/etc/apk/repositories}} to include '''community''', '''edge community''' and '''testing'''.

{{Cat|/etc/apk/repositories|#/media/cdrom/apks
http://dl-cdn.alpinelinux.org/alpine/v3.17/main
http://dl-cdn.alpinelinux.org/alpine/v3.17/community
#http://dl-cdn.alpinelinux.org/alpine/edge/main
http://dl-cdn.alpinelinux.org/alpine/edge/community
http://dl-cdn.alpinelinux.org/alpine/edge/testing}}

=== 2. Node Setup 🖥️ ===

This series of commands solves a series is incremental problems and sets up the system (if the first control node) for kubectl/kubeadm to run properly on next login by linking the config.

The result here gives you a functional node that can be joined to an existing cluster or can become the first control plane of a new cluster. 🎶

{{Note|🔔 This build assumes CNI usage of flannel for networking 🔔}}

'''Add kernel module for networking stuff'''

{{Cmd|# echo "br_netfilter" > /etc/modules-load.d/k8s.conf
# modprobe br_netfilter
# sysctl net.ipv4.ip_forward{{=}}1
# echo "net.ipv4.ip_forward{{=}}1" >> /etc/sysctl.conf
# apk add {{Pkg|cni-plugin-flannel}}
# apk add {{Pkg|cni-plugins}}
# apk add {{Pkg|flannel}}
# apk add {{Pkg|flannel-contrib-cni}}
# apk add {{Pkg|kubelet}}
# apk add {{Pkg|kubeadm}}
# apk add {{Pkg|kubectl}}
# apk add {{Pkg|containerd}}
# apk add {{Pkg|uuidgen}}
# apk add {{Pkg|nfs-utils}}}}

'''Get rid of swap'''

{{Cmd|# cat /etc/fstab | grep -v swap > temp.fstab
# cat temp.fstab > /etc/fstab
# rm temp.fstab
# swapoff -a}}

'''Fix prometheus errors'''

{{Cmd|# mount --make-rshared /
# echo "#!/bin/sh" > /etc/local.d/sharemetrics.start
# echo "mount --make-rshared /" >> /etc/local.d/sharemetrics.start
# chmod +x /etc/local.d/sharemetrics.start
# rc-update add local}}

'''Fix id error messages'''

{{Cmd|# uuidgen > /etc/machine-id}}

'''Add services'''

{{Cmd|# rc-update add containerd
# rc-update add kubelet}}

'''Sync time'''

{{Cmd|# rc-update add ntpd
# rc-service ntpd start
# rc-service containerd start}}

'''Fix flannel'''

''NOTE: This may no longer be necessary on newer versions of the flannel package''

{{Cmd|# ln -s /usr/libexec/cni/flannel-amd64 /usr/libexec/cni/flannel}}

'''Kernel stuff'''

{{Cmd|# echo "net.bridge.bridge-nf-call-iptables{{=}}1" >> /etc/sysctl.conf
# sysctl net.bridge.bridge-nf-call-iptables{{=}}1}}

'''Pin your versions!''' If you update and the nodes get out of sync, it implodes.

{{Cmd|# apk add 'kubelet{{=}}~1.27'
# apk add 'kubeadm{{=}}~1.27'
# apk add 'kubectl{{=}}~1.27'}}

{{Note|In the future you will manually have to add a newer version the same way to upgrade.}}

Your blank node is now ready! If it's the first, you'll want to make a control node.

=== 3. Setup the Control Plane (New Cluster!) 🦾 ===

Run this command to start the cluster and then apply a network.

<pre>
#do not change subnet
kubeadm init --pod-network-cidr=10.244.0.0/16 --node-name=$(hostname)
mkdir ~/.kube
ln -s /etc/kubernetes/admin.conf /root/.kube/config
kubectl apply -f https://raw.githubusercontent.com/flannel-io/flannel/master/Documentation/kube-flannel.yml
</pre>
You now have a control plane. This also gives you the command to run on our blank nodes to add them to this cluster as workers.

=== 4. Join the cluster. 🐜 ===

Run this to get the join command from the control plane which you would then run on your new worker.
<pre>
kubeadm token create --print-join-command
</pre>

= Bonus 💰 =

== Setup NFS Mounts on K8s ==

This can be shared NFS storage to allow for auto persistent claim fulfilment. You'll need your IP updated and export information.

<pre>helm repo add nfs-subdir-external-provisioner https://kubernetes-sigs.github.io/nfs-subdir-external-provisioner/
helm install nfs-subdir-external-provisioner nfs-subdir-external-provisioner/nfs-subdir-external-provisioner \
--set nfs.server=192.168.1.31 \
--set nfs.path=/exports/cluster00
</pre>
Now set the default storage class for the cluster.

<pre>kubectl get storageclass
kubectl patch storageclass nfs-client -p '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"true"}}}'
</pre>
== Check on System 👀 ==

Check on your system.

<pre>kubectl get nodes
kubectl get all
kubectl events -A
</pre>
= Cloud Bonus 🌦️ =

A description of the cloud init version is avalable at [[K8s_with_cloud-init]]

[[Category:Virtualization]]

Alpine Linux - User contributions [en]

K8s