Docs for creation lab K8s

docs/lab-k8s-install.md

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+This document describes k8s installation on our virtual nodes:
+`alio2-bld4-mx-k8s[01..05].cern.ch`. Node `k8s01` was chosen as a control-plane and the rest as worker nodes. These VMs have RHEL 10 installed.
+
+Author first created his own user so the commands used won't be in history of `root`
+`alio2-bld4-mx-k8s01.cern.ch` was chosen as a control plane node and the rest as workers
+
+## kubeadm/kubelet/kubectl installation
+
+[kubeadm/kubelet/kubectl rhel guide](https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/#installing-kubeadm-kubelet-and-kubectl)
+
+- Disable SElinux
+
+One important thing is that SE linux needs to be disabled until SElinux is better supported in kubelet
+It is possible to install kubeadm/cluster with SE enabled, but for now I chose to follow guide to the t.
+
+```
+sudo setenforce 0
+sudo sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config
+```
+
+- Verify all required kernel modules are loaded
+
+RHEL 10 can have problems with having all required kernel modules, you can check:
+```
+lsmod | grep -E 'overlay|br_netfilter|nf_conntrack'
+```
+if there is module not loaded you can try to load it with 
+```
+sudo modprobe br_netfliter
+```
+if you get error that the module is missing:
+```
+sudo dnf install -y kernel-modules-extra
+```
+load all modules now that they are there:
+```
+sudo modprobe overlay
+sudo modprobe br_netfilter
+sudo modprobe nf_conntrack
+lsmod | grep -E 'overlay|br_netfilter|nf_conntrack'
+```
+make the loading persistent:
+```
+cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
+overlay
+br_netfilter
+nf_conntrack
+EOF
+```
+
+- Add Kubernetes yum repo
+
+```
+cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo
+[kubernetes]
+name=Kubernetes
+baseurl=https://pkgs.k8s.io/core:/stable:/v1.36/rpm/
+enabled=1
+gpgcheck=1
+gpgkey=https://pkgs.k8s.io/core:/stable:/v1.36/rpm/repodata/repomd.xml.key
+exclude=kubelet kubeadm kubectl cri-tools kubernetes-cni
+EOF
+```
+
+- Install `kubeadm`, `kubectl` and `kubelet`
+
+Our lab VMware setup uses `dnf4`:
+```
+sudo yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes
+```
+
+Enable kubelet service:
+```
+sudo systemctl enable kubelet.service
+```
+
+- Enable ipv4 forwarding for all nodes and contorl-plane machines
+If 
+```
+sysctl net.ipv4.ip_forward
+```
+returns 0, this sysctl param needs to be added as it is required by setup, param persist across reboots:
+```
+cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
+net.ipv4.ip_forward = 1
+EOF
+```
+
+Apply sysctl params without reboot
+```
+sudo sysctl --system
+```
+
+- Container runtime
+
+[`containerd`](https://github.com/containerd/containerd/blob/main/docs/getting-started.md) was chosen for it's popularity.
+```
+sudo dnf install -y containerd runc
+```
+enable the systemd service
+```
+systemctl daemon-reload
+systemctl enable --now containerd
+```
+RHEL 10 is running cgroups v2 as a default, so we need containerd to use systemd as cgroups driver so add following to the
+`/etc/containerd/config.toml` together with some other changes (like bin dir and other), contents of the config.toml are:
+```
+cat /etc/containerd/config.toml
+version = 2
+
+[plugins]
+  [plugins."io.containerd.grpc.v1.cri"]
+    [plugins."io.containerd.grpc.v1.cri".cni]
+      bin_dir = "/opt/cni/bin"
+      conf_dir = "/etc/cni/net.d"
+    [plugins.'io.containerd.cri.v1.runtime'.containerd.runtimes.runc]
+      [plugins.'io.containerd.cri.v1.runtime'.containerd.runtimes.runc.options]
+        SystemdCgroup = true
+  [plugins."io.containerd.internal.v1.opt"]
+    path = "/var/lib/containerd/opt"
+```
+
+
+and restart the service
+```
+sudo systemctl restart containerd
+sudo systemctl status containerd
+```
+
+# To init Worker node
+
+You need to have Control-plane node ready to proceed!!
+
+- Open following ports: [k8s](https://kubernetes.io/docs/reference/networking/ports-and-protocols/), [calico](https://docs.tigera.io/calico-enterprise/latest/operations/troubleshoot/troubleshooting)
+
+```
+sudo firewall-cmd --permanent --add-port=10250/tcp
+sudo firewall-cmd --permanent --add-port=10256/tcp
+sudo firewall-cmd --permanent --add-port=30000-32767/tcp
+sudo firewall-cmd --permanent --add-port=179/tcp
+sudo firewall-cmd --permanent --add-port=4789/udp
+sudo firewall-cmd --permanent --add-masquerade
+sudo firewall-cmd --permanent --zone=trusted --add-source=192.168.0.0/16
+sudo firewall-cmd --permanent --zone=trusted --add-source=10.96.0.0/12
+sudo firewall-cmd --reload
+```
+
+On control-plane node run
+```
+kubeadm token create --print-join-command
+```
+this command will give you the exact command you are supposed to run on on worker node and it whould look like
+```
+(only demonstrative example) kubeadm join ip.addr:port ...
+```
+
+
+# To init Control plane node
+- Open following ports: [k8s](https://kubernetes.io/docs/reference/networking/ports-and-protocols/), [calico](https://docs.tigera.io/calico-enterprise/latest/operations/troubleshoot/troubleshooting)
+```
+sudo firewall-cmd --permanent --add-port=6443/tcp
+sudo firewall-cmd --permanent --add-port=2379-2380/tcp
+sudo firewall-cmd --permanent --add-port=10250/tcp
+sudo firewall-cmd --permanent --add-port=10259/tcp
+sudo firewall-cmd --permanent --add-port=10257/tcp
+sudo firewall-cmd --permanent --add-port=5473/tcp
+sudo firewall-cmd --permanent --add-port=179/tcp
+sudo firewall-cmd --permanent --add-port=4789/udp
+sudo firewall-cmd --permanent --add-masquerade
+sudo firewall-cmd --permanent --zone=trusted --add-source=192.168.0.0/16
+sudo firewall-cmd --permanent --zone=trusted --add-source=10.96.0.0/12
+sudo firewall-cmd --reload
+```
+
+- run `kubeadm init`
+
+pre run checks on control-plane node:
+```
+swapon --show          # should be empty
+systemctl status containerd   # should be active/running
+which runc              # should resolve
+sysctl net.ipv4.ip_forward    # should be = 1
+
+```
+
+It is advised to use following config file to be used with kubeadm:
+```
+apiVersion: kubeadm.k8s.io/v1beta4
+kind: InitConfiguration
+localAPIEndpoint:
+  advertiseAddress: "10.163.42.208"
+---
+apiVersion: kubeadm.k8s.io/v1beta4
+kind: ClusterConfiguration
+networking:
+  podSubnet: "192.168.0.0/16"
+---
+apiVersion: kubelet.config.k8s.io/v1beta1
+kind: KubeletConfiguration
+cgroupDriver: systemd
+```
+
+Explanation of the settings:
+`localAPIEndpoint`: VMware network has two NICs, one connected to gpn and other for internal communication. this IP is the internal one, which is not a default so it is better to specifically list it 
+`networking`: this defines the pod IP range, and it has to satisfy two things — (1) it must not overlap your existing networks (10.163.0.0/16 internal net or 128.141.175.0/24 gpn), and (2) it must exactly match the CIDR configured in Calico's own custom-resources.yaml (spec.calicoNetwork.ipPools[].cidr),
+`cgroupDriver`: kubelet will use systemd as it needs to match with containerd and systemd is recommended as cgroup driver for cgroups v2
+
+kubeadm invocation
+```
+sudo kubeadm init --config kubeadm-config.yaml
+```
+
+IMPORTANT!! read the output of kubeadm as there might be other requirements which are not fulfilled. 
+
+At this moment we can start "using" the cluster:
+```
+To start using your cluster, you need to run the following as a regular user:
+
+  mkdir -p $HOME/.kube
+  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
+  sudo chown $(id -u):$(id -g) $HOME/.kube/config
+
+Alternatively, if you are the root user, you can run:
+
+  export KUBECONFIG=/etc/kubernetes/admin.conf
+```
+
+after copying cluster config you can check that control-plane is responding (eg.):
+```
+kubectl get nodes
+NAME                          STATUS     ROLES           AGE   VERSION
+alio2-bld4-mx-k8s01.cern.ch   NotReady   control-plane   17m   v1.36.3
+```
+
+The reason why cluster is responding NotReady is that we have no network plugin.
+
+- Calico
+
+documentation for quickstart is [here](https://docs.tigera.io/calico/latest/getting-started/kubernetes/quickstart)
+Right now we are using default settings as the author has no experience with tuning Calico.
+
+Install Calico CRDs:
+```
+kubectl create -f https://raw.githubusercontent.com/projectcalico/calico/v3.32.1/manifests/v1_crd_projectcalico_org.yaml
+```
+Install Tigera operator:
+```
+kubectl create -f https://raw.githubusercontent.com/projectcalico/calico/v3.32.1/manifests/tigera-operator.yaml
+```
+Install Calico by creating the necessary custom resources.
+```
+kubectl create -f https://raw.githubusercontent.com/projectcalico/calico/v3.32.1/manifests/custom-resources.yaml
+```