Kubernetes

Kubernetes#

Sources

Hello minikube tutorial on official k8s site.
kubernetes crashcourse video on youtube.

Setup#

Here’s everything you need to install to start experimenting with Kubernetes on your local machine.

Minicube#

Minikube is local Kubernetes, focusing on making it easy to learn and develop for Kubernetes. Read more in start with minikube page. This is a tool that we’ll use to play with kubernetes.

You need to install it and use the command to start it:

!minikube start &> /dev/null

Once you’ve completed the previous command, you’ll have a corresponding container called minikube in your docker. The following cell shows it.

!docker ps | grep minikube

a29d82ecba5e   gcr.io/k8s-minikube/kicbase:v0.0.44   "/usr/local/bin/entr…"   29 seconds ago   Up 28 seconds   127.0.0.1:32787->22/tcp, 127.0.0.1:32786->2376/tcp, 127.0.0.1:32785->5000/tcp, 127.0.0.1:32784->8443/tcp, 127.0.0.1:32783->32443/tcp   minikube

To make sure everything is OK, try checking the minikube status.

!minikube status

minikube
type: Control Plane
host: Running
kubelet: Running
apiserver: Running
kubeconfig: Configured

You can refresh everything by stopping and deleting the minikube container.

!minikube delete

🔥  Deleting "minikube" in docker ...
🔥  Deleting container "minikube" ...
🔥  Removing /home/f.kobak@maxbit.local/.minikube/machines/minikube ...
💀  Removed all traces of the "minikube" cluster.

kubectl#

kubectl is a command line interface that allows you to interact with Kubernetes, in particular with Kubernetes started with minikube. Check the installation guide.

For me, using the ubunty option snap install kubectl --classic worked well.

!kubectl version --client

Client Version: v1.29.5
Kustomize Version: v5.0.4-0.20230601165947-6ce0bf390ce3

Core components#

Here we will discuss components of the kubernetes:

Pod is a group of containers.
Deployment is an abstraction that manages pods.
Service is pod that was exposed.

Creating hello-node deployment.

!kubectl create deployment hello-node --image=registry.k8s.io/e2e-test-images/agnhost:2.39 -- /agnhost netexec --http-port=8080

deployment.apps/hello-node created

Now we can access the deployments list:

!kubectl get deployments

NAME         READY   UP-TO-DATE   AVAILABLE   AGE
hello-node   1/1     1            1           51s

It have a pod that can be listed using the appropriate command:

!kubectl get pods

NAME                          READY   STATUS    RESTARTS   AGE
hello-node-55fdcd95bf-v9w97   1/1     Running   0          2m18s

Now we only have a basic service that runs on k8s.

!kubectl get services

NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   5m17s

But after exposing hello-node we’ll have one more service.

%%bash
kubectl expose deployment hello-node --type=LoadBalancer --port=8080
kubectl get services

Error from server (AlreadyExists): services "hello-node" already exists

NAME         TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
hello-node   LoadBalancer   10.97.143.213   <pending>     8080:32657/TCP   90s
kubernetes   ClusterIP      10.96.0.1       <none>        443/TCP          7m57s