K8s
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
Build K8s on Alpine Linux 🌲
Prerequisites 🔍
You need an 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.
For HA control planes you'll need a mininum of three nodes
1. Setup the Repositories 📗
Update you repositories under /etc/apk/repositories to include community, edge community and testing.
Contents of /etc/apk/repositories
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. 🎶
Add kernel module for networking stuff
# echo "br_netfilter" > /etc/modules-load.d/k8s.conf # modprobe br_netfilter # echo 1 > /proc/sys/net/ipv4/ip_forward # apk add cni-plugin-flannel # apk add cni-plugins # apk add flannel # apk add flannel-contrib-cni # apk add kubelet # apk add kubeadm # apk add kubectl # apk add containerd # apk add uuidgen # apk add nfs-utils
Get rid of swap
# cat /etc/fstab
Fix prometheus errors
# 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
# uuidgen > /etc/machine-id
Add services
# rc-update add containerd # rc-update add kubelet
Sync time
# rc-update add ntpd # /etc/init.d/ntpd start # /etc/init.d/containerd start
Fix flannel
# ln -s /usr/libexec/cni/flannel-amd64 /usr/libexec/cni/flannel
Kernel stuff
# 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.
# apk add 'kubelet=~1.26' # apk add 'kubeadm=~1.26' # apk add 'kubectl=~1.26'
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.
#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
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.
kubeadm token create --print-join-command
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.
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
Now set the default storage class for the cluster.
kubectl get storageclass
kubectl patch storageclass nfs-client -p '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"true"}}}'
Check on System 👀
Check on your system.
kubectl get nodes kubectl get all