This project aims to demonstrate how one can create minimal and immutable Kubernetes OS images with LinuxKit.
To build images and to rebuild the individual packages you will need the LinuxKit tool
If you already have go installed you can use go get -u github.com/linuxkit/linuxkit/src/cmd/linuxkit to install the tool.
On MacOS there is a brew tap available. Detailed instructions are at linuxkit/homebrew-linuxkit, the short summary is
brew tap linuxkit/linuxkit
brew install --HEAD linuxkit
Build requirements from source:
makeqemuTo build the default OS images:
By default this will build images using Docker Engine for execution. To instead use cri-containerd use:
make all KUBE_RUNTIME=cri-containerd
Boot Kubernetes master OS image using hyperkit on macOS: or qemu on Linux:
or, to automatically initialise the cluster upon boot with no additional options
KUBE_MASTER_AUTOINIT="" ./boot.sh
Get IP address of the master:
Login to the kubelet container:
./ssh_into_kubelet.sh <master-ip>
Manually initialise master with kubeadm if booted without KUBE_MASTER_AUTOINIT:
Once kubeadm exits, make sure to copy the kubeadm join arguments, and try kubectl get nodes from within the master.
If you just want to run a single node cluster with jobs running on the master, you can use:
kubectl taint nodes --all node-role.kubernetes.io/master- --kubeconfig /etc/kubernetes/admin.conf
To boot a node use:
./boot.sh <n> [<join_args> ...]
More specifically, to start 3 nodes use 3 separate shells and run this:
shell1> ./boot.sh 1 --token bb38c6.117e66eabbbce07d 192.168.65.22:6443 --discovery-token-unsafe-skip-ca-verification
shell2> ./boot.sh 2 --token bb38c6.117e66eabbbce07d 192.168.65.22:6443 --discovery-token-unsafe-skip-ca-verification
shell3> ./boot.sh 3 --token bb38c6.117e66eabbbce07d 192.168.65.22:6443 --discovery-token-unsafe-skip-ca-verification
The above instructions should work as is.
By default linuxkit run uses user mode networking which does not support access from the host. To workaround this you can use port forwarding e.g.
KUBE_RUN_ARGS="-publish 2222:22" ./boot.sh
ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -p 2222 root@localhost
However you will not be able to run worker nodes since individual instances cannot see each other.
To enable networking between instance unfortunately requires root privileges to configure a bridge and setup the bridge mode privileged helper.
See http://wiki.qemu.org/Features/HelperNetworking for details in brief you will need:
To setup and configure a bridge (including e.g. DHCP etc) on the host. (You can reuse a bridge created by e.g. virt-mananger)
To set the qemu-bridge-helper setuid root. The location differs by distro, it could be /usr/lib/qemu/qemu-bridge-helper or /usr/local/libexec/qemu-bridge-helper or elsewhere. You need to chmod u+s «PATH».
List the bridge created in the first step in /etc/qemu/bridge.conf with a line like allow br0 (if your bridge is called br0).
Set KUBE_NETWORKING=bridge,«name» e.g.
KUBE_NETWORKING="bridge,br0" ./boot.sh KUBE_NETWORKING="bridge,br0" ./boot.sh 1 «options»
The boot.sh script has various configuration variables at the top which can be overridden via the environment e.g.
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