Repository for the K8s in 1 hour video (https://www.youtube.com/watch?v=s_o8dwzRlu4)

This is an example Kubernetes project that creates a simple example Node app with MongoDB, and configures the server environment with .env vars for the Node app, and configures the Mongo db with an initial user.

The project will look like this:

The basics of Kubernetes: https://www.doabledanny.com/kubernetes-basics

K8s manifest files

("K8" is shorthand for Kubernetes. It refers to the eight letters between the "K" and "s" in Kubernetes (Kubernetes))

• mongo-config.yaml
• mongo-secret.yaml
• mongo.yaml
• webapp.yaml

K8s commands

start Minikube and check status

minikube start (ensure you've opened up Docker Desktop first)
minikube status

get minikube node's ip address

minikube ip

get basic info about k8s components

kubectl get node
kubectl get pod (see pods)
kubectl get svc
kubectl get all (see all components in the cluster -- but it doesn't show configMap and Secret, so:)
kubectl get configmap
kubectl get secret

Config Kubernetes

Apply command manages applications through files containing K8s resources. -f stands for file. Whatever is defined in the file is created, e.g. ConfigMap, Service, Deployment etc.:

kubectl apply -f mongo-congig.yaml
kubectl apply -f mongo-secret.yaml
kubectl apply -f mongo.yaml
kubectl apply -f webapp.yaml

Notice that we created mongo config and secret first, because the mongo db depends on it, and we create the mongo db before the webapp, because the webapp depends on it.

get extended info about components

kubectl get pod -o wide
kubectl get node -o wide (can also get the cluster ip with this as well as `minkube ip`)

get detailed info about a specific component

kubectl describe svc {svc-name}
kubectl describe pod {pod-name}

get application logs

kubectl logs {pod-name}

e.g. kubectl logs webapp-deployment-7f479b7c79-v828v => "app listening on port 3000!"

You can also stream the logs with -f option: kubectl logs webapp-deployment-7f479b7c79-v828v -f

Access app in browser

1. Find what public ip the cluster is available on with kubectl get node -o wide => INTERNAL-IP or minikube up.
2. Find the NodePort number: look inside your webapp's service config for nodePort, or kubectl get svc
3. Access MinikubeIP:NodePort in the browser, e.g. http://192.168.49.2:30100/

Or, if that doesn't work:

stop your Minikube cluster

minikube stop

⚠️ Known issue - Minikube IP not accessible

If you can't access the NodePort service webapp with MinikubeIP:NodePort, execute the following command:

minikube service webapp-service

Deleting components

Delete all: kubectl delete all --all

Delete configmap: kubectl delete configmap configmap-name

Delete secret: kubectl delete secret secret-name

Delete service: kubectl delete svc service-name

Links

• mongodb image on Docker Hub: https://hub.docker.com/_/mongo
• webapp image on Docker Hub: https://hub.docker.com/repository/docker/nanajanashia/k8s-demo-app
• k8s official documentation: https://kubernetes.io/docs/home/
• webapp code repo: https://gitlab.com/nanuchi/developing-with-docker/-/tree/feature/k8s-in-hour