Kubernetes Basics Tutorial

My introduction to managing kubernetes. Trying to grow my knowledge of k8s outside of my usual GKE infrastructure configuration and troubleshooting role.

Prerequisites

• minikube
• kubectl
• hyperkit
• docker CLI

Usage

Start Minikube Cluster

Start Minikube using kyperkid VM driver

minikube start --driver=hyperkit

Create the standard namespace To-do: I'm creating everything under the same namespace. It's a tiny app so who cares.. just for demonstration purposes.

kubectl apply -f namespace.yaml

Setup Mongo

Create secrets for MongoDB username and password

echo -n 'username' | base64
echo -n 'password' | base64

Apply secrets

kubectl apply -f mongo-secret.yaml

Apply Mongo DB Deployment and Service

kubectl apply -f mongo.yaml

Apply Mongo Express Config Map

kubectl apply -f mongo-configmap.yaml

Apply Mongo Express Deployment and Service

kubectl apply -f mongo-express.yaml

Assign External IP to Mongo Express LB Service

minikube service mongo-express-service

Setup Flask App

I'm using Docker Hub...

Build the docker file

docker build -t <USERNAME>/flask-kubernetes .

Login to Docker Hub

docker login

Push the image to Docker Hub

docker push <USERNAME>/flask-kubernetes

Run the image locally to test

docker run -p 5000:5000 <USERNAME>/flask-kubernetes:latest

Apply Flask App Deployment and Service

kubectl apply -f flask-app.yaml

Apply Flask App Ingress

kubectl apply -f flask-ingress.yaml

The domain name flaskapp.com doesnt belong to me. To make this work in the local environment, add flaskapp.com to your /etc/hosts file

Get the Address from the ingress service

kubectl describe ingress -n flask-app-ns

Edit your hosts file

vim /etc/hosts

Add the hosts entry

<INGRESS ADDRESS>    flaskapp.com

Basic Commands for Checking on the Cluster

Check on your cluster

kubectl get all
kubectl get deployment
kubectl get service
kubectl get pod -o wide # helps get the IPs to compare to service endpoints
kubectl describe service <SERVICE_NAME>

Docker Hub Image Links

• MongoDB Official Image
• Mongo Express Official Image

Migrating to Helm Chart

My next step is converting this configuration to a Helm chart. I'm interested in seeing the value of the CLI tool, Helmify, to make conversion easier.

I ran Helmify against the entire k8s directory and it seems to have succeeded.

awk 'FNR==1 && NR!=1  {print "---"}{print}' ./k8s/*.yaml | helmify flask-mongo-example-helm

To-do: run the helm chart and confirm functionality.

Deploying to Google Kubernetes Engine

The "terraform" directory contains HCL for building out a GCP project and a basic GKE-standard cluster.

Steps for Terraform

Initialize Terraform

terraform init

Run Terraform Plan

terraform plan -var-file=dev.tfvars

Run Terraform Plan

terraform apply -var-file=dev.tfvars

Deploy to the GKE cluster

Get the cluster credentials

gcloud container clusters get-credentials flask-app-cluster --region=us-central1-b

Deploy our config - still havent made this into a Helm chart

kubectl apply -f namespace.yaml
kubectl apply -f mongo-secret.yaml
kubectl apply -f mongo-configmap.yaml
kubectl apply -f mongo.yaml
kubectl apply -f flask-app.yaml
kubectl apply -f flask-ingress.yaml

Wait for an IP on ingress, and visit in a browser

kubectl get flask-ingress -n flask-app-ns