kubernetes: add README

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

recipes-containers/kubernetes/README.md

@@ -0,0 +1,117 @@
+# k8s: Kubernetes
+
+meta-virtualization provides the recipes and packages suitable for a k8s
+cluster instance.
+
+For a kubernetes controller:
+
+  - packagegroup-k8s-host
+
+For a kubernetes worker/node:
+
+  - packagegroup-k8s-node
+
+If kernel issues or missing features are detected, consider adding the
+"kernel-modules" package to your image (Since the configuration and RDEPENDS
+may not be correct for your kernel + k8s version).
+
+## CNI
+
+The CNI base packages provide core support and are installed by default as
+dependencies of the kubernetes packages. Minimal configuration and startup
+are provided, but you will need to apply the CNI configuration of your choice
+after boot (see below fo an example)
+
+## Configure and initialize the host
+
+A convenience script "k8s-init" is provided to do basic setup on the controller
+node. After the contoller boots, run it for kubeadm setup and other basic
+configuration.
+
+Once the node is ready ('kubectl get nodes' to check), follow the instructions
+for copying the token to your home directory, and apply the networking configuration
+of choice (flannel in the example):
+
+```shell
+  % mkdir -p $HOME/.kube
+  % cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
+  % chown $(id -u):$(id -g) $HOME/.kube/config
+
+  % kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
+```
+
+## Configuration and initialize the node/worker
+
+Once the kubernetes node has booted, it is ready to join the cluster. Some
+basica configuration is done via the packages and a systctl.d configuration
+snippet.
+
+Join the cluster (substitute your controller ip and token information):
+
+```shell
+kubeadm join <controller ip>:6443 --token cq8ngi.6m6mgqi9zf08ypc4 --discovery-token-ca-cert-hash sha256:6064ae531c8dad824f9eadff030f83ec84d00796fac75f1adbd343255eb34fd2
+```
+
+## Notes:
+
+Memory:
+
+  if running under qemu, the default of 256M of memory is not enough, k3s will
+  OOM and exit.
+
+  Boot with qemuparams="-m 2048" to boot with 2G of memory (or choose the
+  appropriate amount for your configuration)
+
+CPUs:
+
+  Kubernetes needs at least two cpus, so ensure your qemuboot is smp of at
+  least 2, and/or that your hardware has the required capabilties.
+
+Disk:
+
+  if using qemu and core-image* you'll need to add extra space in your disks
+  to ensure containers can start. The following in your image recipe, or
+  local.conf would add 2G of extra space to the rootfs:
+
+```shell
+IMAGE_ROOTFS_EXTRA_SPACE = "2097152"
+```
+
+## Example qemux86-64 boot line:
+
+```shell
+runqemu qemux86-64 nographic kvm slirp qemuparams="-m 2048"
+```
+k8s logs can be seen via:
+
+```shell
+% journalctl -u kubelet
+```
+
+or
+
+```shell
+% journalctl -xe
+```
+
+## Example output from qemux86-64:
+
+If you've lost the join token, you can create a new one, or list existing
+ones:
+
+```shell
+root@qemux86-64-7b:~# kubeadm token create --print-join-command
+kubeadm join 10.10.10.117:6443 --token dr71zq.y5vi3s2n2antvcej --discovery-token-ca-cert-hash sha256:6064ae531c8dad824f9eadff030f83ec84d00796fac75f1adbd343255eb34fd2
+
+root@qemux86-64-7b:~# kubeadm token list
+TOKEN                     TTL         EXPIRES                USAGES                   DESCRIPTION                                                EXTRA GROUPS
+cq8ngi.6m6mgqi9zf08ypc4   23h         2021-12-16T16:58:02Z   authentication,signing   The default bootstrap token generated by 'kubeadm init'.   system:bootstrappers:kubeadm:default-node-token
+dr71zq.y5vi3s2n2antvcej   23h         2021-12-16T17:46:28Z   authentication,signing   <none>                                                     system:bootstrappers:kubeadm:default-node-token
+```
+
+```shell
+root@qemux86-64:~# kubectl get nodes
+NAME            STATUS   ROLES                  AGE   VERSION
+qemux86-64-7b   Ready    control-plane,master   51m   v1.23.1-rc.0.1+dd1b0a12471310-dirty
+qemux86-64-9d   Ready    <none>                 49m   v1.23.1-rc.0.1+dd1b0a12471310-dirty
+```