Hosting service on Kubernetes using `microk8s`

Prerequisites

The basic prerequisite for this lab is to setup a virtual machine (master node) and create two worker nodes with same configuration as master node

Troubleshoot if kubectl get nodes not working

Step 1: Login to your virtual machines

Step 2: To verify the kubectl and microk8s running use the following command

First, check the status of your MicroK8s cluster to ensure it's running:

microk8s status

If it's not running, you can start it with:
```
microk8s start
```
If it is running but some services are disabled, you can enable essential services like DNS, the API server, and the dashboard:
```
microk8s enable dns dashboard
```

Use MicroK8s kubectl Command

To retrieve the node details

microk8s kubectl get nodes

Step 3: Check permissions

Ensure your user is part of the microk8s group so that you don’t need sudo for every command:

Add your user to the microk8s group:
```
sudo usermod -a -G microk8s $USER
```
Then apply the new group membership:
```
newgrp microk8s
```

Step 4: Configure Kubeconfig for kubectl

If you prefer to use the system-wide kubectl rather than microk8s kubectl, you need to configure kubectl to point to the MicroK8s configuration. MicroK8s stores its kubeconfig in a specific location:

Export the MicroK8s kubeconfig for use with kubectl:

sudo microk8s kubectl config view --raw > ~/.kube/config

This will set kubectl to use MicroK8s' configuration.

Step 5: Check Cluster Info

Once the cluster is running and configured correctly, verify that it’s up by checking the cluster information:

microk8s kubectl cluster-info

If the cluster info is correct, you should see information about the API server and other services.

Step 6: Restart MicroK8s (if needed)

If you're still facing issues, you can try restarting MicroK8s:

microk8s stop
microk8s start

Configure the master node

Step 1: Add worker nodes with master node

Run the add command in master node

microk8s add-node

Output:

student@int363:~$ microk8s add-node
From the node you wish to join to this cluster, run the following:
microk8s join 172.31.83.178:25000/a4c5194f8027dbe1df17b63b5753c0e3/1113bd240a17

Use the '--worker' flag to join a node as a worker not running the control plane, eg:
microk8s join 172.31.83.178:25000/a4c5194f8027dbe1df17b63b5753c0e3/1113bd240a17 --worker

If the node you are adding is not reachable through the default interface you can use one of the following:
microk8s join 172.31.83.178:25000/a4c5194f8027dbe1df17b63b5753c0e3/1113bd240a17
microk8s join 172.17.0.1:25000/a4c5194f8027dbe1df17b63b5753c0e3/1113bd240a17

Copy the join command and paste in the wokrre node with --worker flag

microk8s join PRIVATE_IP:25000/TOKEN --worker

Output:

student@int363:~$ microk8s join 172.31.83.178:25000/a4c5194f8027dbe1df17b63b5753c0e3/1113bd240a17 --worker
WARNING: Hostpath storage is enabled and is not suitable for multi node clusters.

Contacting cluster at 172.31.83.178

The node has joined the cluster and will appear in the nodes list in a few seconds.

This worker node gets automatically configured with the API server endpoints.
If the API servers are behind a loadbalancer please set the '--refresh-interval' to '0s' in:
    /var/snap/microk8s/current/args/apiserver-proxy
and replace the API server endpoints with the one provided by the loadbalancer in:
    /var/snap/microk8s/current/args/traefik/provider.yaml

Successfully joined the cluster.

Note: Repeat the step 1 to add a new node. Should not use the same token to connect multiple nodes

Step 2: Create a deployment in the master node

kubectl create deployment microbot --image=dontrebootme/microbot:v1

Here microbot is the deployment name

Step 3: Create replicaset of the deployment for scalability

kubectl scale deployment workshop --replicas=2

Step 4: Expost the port 80 so the application can be accessible

kubectl expose deployment workshop --type=NodePort --port=80 --name=microbot-service

Step 5: Now verify the namespace and look for service/microbot-service and note the port (generated and assigned randomly)

default              service/microbot-service            NodePort       10.152.183.251   <none>        80:32475/TCP                                                                 21m

Open the browser and open the port -

Command	Description
Local machine	http://localhost:PORT
Remote machine	http://PUBLIC_ADDRESS:PORT

Optional

To remove a node from the cluster

Run microk8s leave command on worker node you want to dettach from cluster.
RUn following command on master node

microk8s remove-node

All Verification

Command	Description
`kubectl get all --all-namespaces`	List all namespaces in the cluster
`kubectl get namespace`	List namespaces in the cluster
`kubectl get nodes`	List all nodes in the cluster
`kubectl cluster-info`	Display cluster information
`kubectl get services`	List all services in the current namespace
`kubectl get pods`	List all pods in the current namespace
`kubectl get deployments`	List all deployments in the current namespace
`kubectl get svc`	List all services in the current namespace

You can append microk8s in the command as a prefix before excuting.

For more commands refer to Kubernetes Command Cheatsheet

Lab 04 - Creating a service and deploying using docker Lab 06 - Create pod and launch NGINX server

Hosting service on Kubernetes using microk8s

Prerequisites

Configure the master node

Optional

All Verification

Hosting service on Kubernetes using `microk8s`