Setting Up a Kubernetes Cluster With Containerd

containerd works well for running single containers or small groups of containers on a single host. But what if you have more than a few containers, or want those containers to be spread across multiple servers, or even made highly available?

For these scenarios, you'll need a container orchestrator. Kubernetes is a popular container orchestration framework that easily works with containerd. In this lab, you'll learn to set up a Kubernetes cluster with containerd.

Configure the Kubernetes Cluster

On all three nodes, add the Kubernetes repo to /etc/yum.repos.d:
```
cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo
```

Install the repo:

[kubernetes]
name=Kubernetes
baseurl=https://pkgs.k8s.io/core:/stable:/v1.30/rpm/
enabled=1
gpgcheck=1
gpgkey=https://pkgs.k8s.io/core:/stable:/v1.30/rpm/repodata/repomd.xml.key
exclude=kubelet kubeadm kubectl cri-tools kubernetes-cni
EOF

Disable SELinux:

sudo setenforce 0
sudo sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

Install Kubernetes:

sudo yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes

Enable and start kubelet:

sudo systemctl enable --now kubelet 6. Check your containerd status on all nodes:

sudo ctr -n k8s.io containers list

From Node 1, initialize the controller node, and set the code network CIDR to 10.244.0.0/16:
```
sudo kubeadm init --pod-network-cidr=10.244.0.0/16
```

Run the following commands to start using the cluster:

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

Copy the sudo kubeadm join command, then paste and run it in your Node 2, and Node 3 terminal windows.

sudo kubeadm join <YOUR_IP>:6443 --token <YOUR_TOKEN> \
--discovery-token-ca-cert-hash sha256:<YOUR_HASH>

From the worker nodes, verify that they can see the cluster:
```
sudo ctr -n k8s.io containers list
```
From Node 1, check the status of the nodes:
```
kubectl get nodes
```

Install Flannel:

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

Create a Pod

Create the pod.yml file:
```
vim pod.yml
```

In the file, paste the following:

apiVersion: v1
kind: Pod
metadata:
name: nginx-pod-demo
labels:
    app: nginx-demo
spec:
containers:
- image: nginx:latest
    name: nginx-demo
    ports:
    -  containerPort: 80
    imagePullPolicy: Always

Save the file:

ESC
:wq

Create the pod:

kubectl apply -f pod.yml

Check the status of the pod:

kubectl get pods

Create the Service

Create the service.yml file:
```
vim service.yml
```

In the file, paste the following:

apiVersion: v1
kind: Service
metadata:
name: service-demo
spec:
selector:
    app: nginx-demo
ports:
- protocol: TCP
    port: 80
    targetPort: 80
type: NodePort

Save the file:
```
ESC
:wq
```
Create the service:
```
kubectl apply -f service.yml
```
Run the following command to view the service:
```
kubectl get services
```
Take note of the service-demo port number.
In a web browser, navigate to the public IP address for a server in the cluster, and verify connectivity:
```
<PUBLIC_IP_ADDRESS>:<SERVICE_DEMO_PORT_NUMBER>
```

END