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Kubernetes cluster on a Raspberry Pi
Learn how you can build your own Kubernetes cluster on Raspberry Pi. In this post, I will explains how to install Raspbian Stretch Lite image on an SD card. You will need another computer with an SD card reader to install the image.
- 4 x Raspberry Pi 3 B+
- 5 x MicroSD cards
- 4 x 1ft Micro USB cables
- 4 x 1ft Cat cables
- 1 x Multi-Pi Stackable Case
- 1 x Desktop USB Port Charger
- 1 x 8-Port Network Switch
Official images for Raspbian Stretch Lite is available to download from the Raspberry Pi website Downloads page.
You will need to use an image writing tool to install the image you have downloaded on your SD card.
Etcher is a graphical SD card writing tool that works on Mac OS, Linux and Windows, and is the easiest option for most users. Etcher also supports writing images directly from the zip file, without any unzipping required. To write your image with Etcher:
- Download Etcher and install it.
- Connect an SD card reader with the SD card inside.
- Open Etcher and select from your hard drive the Raspberry Pi .img or .zip file you wish to write to the SD card.
- Select the SD card you wish to write your image to.
- Review your selections and click 'Flash!' to begin writing data to the SD card.
Etcher automatically ejects the drive when the flashing procedure is completed, so you may have to remove and reinsert the microSD card in your computer.
- to enable SSH access, create an empty file called “ssh” (no file extension!) and put it on the microSD card (/boot)
- to enable WiFi, create a file called “wpa_supplicant.conf” with following content, on the microSD card (/boot):
country=US
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
ssid="<your_ssid>"
psk="<your_password>"
key_mgmt=WPA-PSK
}
More information on How to Setup Wi-Fi On Your Raspberry Pi via the Command Line
The security of your Raspberry Pi is important. Gaps in security leave your Raspberry Pi open to hackers who can then use it without your permission.
passwd
To add a new user, enter:
sudo adduser sayem
To add them to the sudo group to give them sudo permissions:
sudo adduser sayem sudo
Force sudo to require a password, enter:
sudo nano /etc/sudoers.d/010_pi-nopasswd
and change the pi entry (or whichever usernames have superuser rights) to:
sayem ALL=(ALL) PASSWD: ALL
More information on Securing your Raspberry Pi
It is possible to configure your Raspberry Pi to allow your computer to access it without providing a password each time you try to connect. To do this you need to generate an SSH key:
ls ~/.ssh
If you don't have an existing SSH key, you can Generate a new SSH key and adding it to the ssh-agent
ssh-copy-id <USERNAME>@<IP-ADDRESS>
Alternatively, if the ssh-copy-id is not available on your system, you can copy the file manually over SSH:
cat ~/.ssh/id_rsa.pub | ssh <USERNAME>@<IP-ADDRESS> 'mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys'
Now try ssh <USER>@<IP-ADDRESS> and you should connect without a password prompt.
More information on Passwordless SSH access
sudo raspi-config
- Select Network Options
- Select
N1 Hostnameto change hostname
Go back to main menu
- Select option
4 Localisation Options - Select
T1 Change Localeto change Locale
Go back to Change Localisation menu
- Select
Change Timezoneto change your Timezone
Go back to Change Localisation menu
- Select
I4 Change Wi-fi Countryto your country
sudo reboot
curl -sSL get.docker.com | sh && \
sudo usermod -aG docker sayem \
newgrp docker
sudo dphys-swapfile swapoff && \
sudo dphys-swapfile uninstall && \
sudo update-rc.d dphys-swapfile remove
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add - && \
echo "deb http://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list && \
sudo apt-get update -q && \
sudo apt-get install -qy kubeadm
Next we need to edit the /boot/cmdline.txt file. Run the following command to add cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory in the end of the file. This needs to be in the same line as all the other text in the file. Do not create a new file.
echo Adding " cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory" to /boot/cmdline.txt
sudo cp /boot/cmdline.txt /boot/cmdline_backup.txt
orig="$(head -n1 /boot/cmdline.txt) cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory"
echo $orig | sudo tee /boot/cmdline.txt
sudo reboot
This bit of setup is just for the master node.
- Pre-pull images
sudo kubeadm config images pull -v3
- We will be using Weave Net as a network overlay.
sudo kubeadm init --token-ttl=0
The - -token-ttl = 0 makes sure our token doesn’t expire. This is not a good practice and should not be done in production.
This will take a long time....
Save your join token to a text-editor. This will be used to add additional nodes (machines) to your cluster. It should look something like this:
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')"
kubectl get pods --namespace=kube-system
NAME READY STATUS RESTARTS AGE
coredns-86c58d9df4-hjdg6 1/1 Running 0 176m
coredns-86c58d9df4-tp4qf 1/1 Running 0 176m
etcd-k8s-master 1/1 Running 0 175m
kube-apiserver-k8s-master 1/1 Running 0 176m
kube-controller-manager-k8s-master 1/1 Running 0 175m
kube-proxy-c5wpj 1/1 Running 0 174m
kube-proxy-gg758 1/1 Running 0 176m
kube-proxy-pdrp9 1/1 Running 0 174m
kube-proxy-txtnm 1/1 Running 0 174m
kube-scheduler-k8s-master 1/1 Running 0 175m
weave-net-8qjtm 2/2 Running 0 174m
weave-net-ncbbh 2/2 Running 0 175m
weave-net-nd44p 2/2 Running 0 174m
weave-net-rj8mk 2/2 Running 0 174m
sudo sysctl net.bridge.bridge-nf-call-iptables=1
You can now join any number of machines by running the following on each node as root:
sudo kubeadm join --token <token> <master-node-ip>:6443 --discovery-token-ca-cert-hash sha256:<sha256>
kubectl get nodes
NAME STATUS ROLES AGE VERSION
k8s-master Ready master 3h25m v1.13.4
k8s-node1 Ready <none> 3h23m v1.13.4
k8s-node2 Ready <none> 3h23m v1.13.4
k8s-node3 Ready <none> 3h22m v1.13.4
And with this the cluster setup is done.