ProductsStore on Kubernetes

This is a sample application used to demonstrate how to create dockerized apps and deploy them to Kubernetes cluster.

It takes a sample ASP.NET Core MVC app, creates its Dockerfile, then the Kubernetes deployment objects.

The Dockerfile is used to build the app from source code. Then runs the app inside a docker container.
The k8s objects defined in YAML files are used to deploy the app into a Kubernetes cluster. These files are:

1. mvc-deployment.yaml: used to create a Deployment and a Service to run the app.
2. mssql-deployment.yaml: used to create a Deployment and a Service to run the SQL Server container.
3. mssql-config-map.yaml: creates a ConfigMap object to store the database connection string as key-value pair. It is accessed by the app to retrieve the connection string as apass it as environment variable.
4. mssql-secret.yaml: creates a Secret to securely save database connection string as key-value pair.
5. mssql-pv.azure.yaml: creates PersistentVolume and PersistentVolumeClaim objects in order to provision a storage space to save the database files.

1) Introduction: Kubernetes and microservices

1.1) The vision: Microservices on Docker containers on Kubernetes hosted on the Cloud and powered by DevOps.

Source: https://blog.nebrass.fr/playing-with-spring-boot-on-kubernetes/

1.2) Learn more about Kubernetes architecture:

1.3) Learn more about Kubernetes objects: Deployment, Service, ConfigMap, Secret, PersistentVolume...

2) Create docker container

Inside the MvcApp folder, we have a sample ASP.NET Core MVC application that displays web pages and connects to a Database. The goal here is to run this application in a Docker container. For that, we need the Dockerfile which describes the instructions to build/compile app from source code and deploy it into a base image that have .NET Core SDK and Runtime.

2.0) Install Docker into your machine Make sure you have Docker installed and running in your machine: Docker Desktop

2.1) Start Docker in your machine and check if it runs successfully by deploying a sample image called hello-world:

$ docker run hello-world  
  Hello from Docker!  
  This message shows that your installation appears to be working correctly.    
2.2) Create Docker image  
$ cd MvcApp  
$ docker build .     # don't forget the dot at the end to configure thecontext!  
$ docker build --rm -f "Dockerfile" -t mvc-app:1.0 .   
2.3) List the created image  
$ docker images  
2.4) Run the created image  
$ docker run --rm -d -p 5555:80/tcp mvc-app:1.0   
2.5) List the running image  
$ docker ps  
2.6) Open browser on localhost:5555 and note how the app doesn't connect to database despite it is configured to!!  
2.7) Configure and start SQL Server on container  
$ docker run -e 'ACCEPT_EULA=Y' -e 'SA_PASSWORD=@Aa123456' -p 1433:1433 -d mcr.microsoft.com/mssql/server:2019-CU4-ubuntu-16.04  

3) Run the App using docker-compose

When dealing with multiple containers, Docker Compose becomes really useful. It allows to define the configuration in a single file. This file then will be used to build, deploy and stop all the images using docker-compose CLI. Open the docker-compose.yaml file. Note how we are defining 2 services: one to run the web app and a second one to deploy the database.

3.1) Build the Docker Compose file to create the images  
$ docker-compose build  
3.2) Run the Docker Compose file to run the created images  
$ docker-compose up  
  Starting sqldb-k8s     ... done  
  Starting mvcapp-k8s    ... done  

4) Push containers to Docker Hub

Now that we have created the docker image in our machine, we want to deploy it into Kubernetes. But, Kubernetes should get that image through a Container Registry. Container Registry is a like a database for all our containers. We can use Azure ACR or Docker Hub... We'll continue with Docker Hub. Make sure you create a an account here hub.docker.com and take note of your Docker Hub ID (Registry name).

4.1) Create a variable to hold our Registry name  
$ $registry="REPLACE_WITH_YOUR_DOCKER_HUB_ID"  
4.2) Tag the image by appending the registry name  
$ docker tag mvc-app:1.0 $registry/mvc-app:1.0  
4.3) Login to Docker Hub and enter your login and password    
$ docker login  
4.4) Push the image into the registry  
$ docker push $registry/mvc-app:1.0  
4.5) Check your hub.docker.io, you should see the image uploaded into a repository

5) Deploy to Minikube/Kubernetes using the Dashboard

5.1) Start the Dashboard  
5.2) $ minikube start  
5.3) $ minikube dashboard  

6) Deploy to Kubernetes using Kubectl CLI

6.1) $ Kubectl run …  
6.2) $ kubectl get deployments  
6.3) $ kubectl get secrets  
6.4) $ kubectl get services  

7) Deploy to Kubernetes using configuration YAML files

7.1) $ kubectl apply -f mssql-secret.yaml  
     $ kubectl get secrets   
7.2) $ kubectl apply -f mssql-pv.azure.yaml  
     $ kubectl get pv  
7.3) $ kubectl apply -f mssql-deployment.yaml  
     $ kubectl get deployments  
7.4  $ kubectl apply -f mvc-deployment.azure.yaml  
     $ kubectl get deployments  
7.5) $ minikube config set memory 4096  # if we need to resize minikube  
7.6) $ kubectl delete services,deployments,pvc,secrets --all -n default

8) Create managed Kubernetes cluster in Azure using AKS

8.1) $ az group create \  
		  --location westeurope \  
		  --subscription "Microsoft Azure Sponsorship" \  
		  --name aks-k8s-rg  
8.2) $ az aks create \  
		  --generate-ssh-keys \  
		  --subscription "Microsoft Azure Sponsorship" \  
		  --node-count 1 \  
		  --resource-group aks-k8s-rg \  
		  --name aks-k8s   
8.3) $ az aks get-credentials \  
		  --resource-group aks-k8s-rg \  
		  --name aks-k8s \  
		  --subscription "Microsoft Azure Sponsorship" 
	 Merged "aks-k8s" as current context in /Users/houssem/.kube/config  
8.4) $ kubectl create clusterrolebinding kubernetes-dashboard \  
               --clusterrole=cluster-admin \  
               --serviceaccount=kube-system:kubernetes-dashboard  
8.5) $ az aks browse \
		  --resource-group aks-k8s-rg \
		  --name aks-k8s \
		  --subscription "Microsoft Azure Sponsorship"  

9) Create the CI/CD pipelines for using Azure DevOps

9.1) CI pipeline: builds the container and pushes it to docker hub.  

9.2) CD pipeline: deploys the YAML manifest files into Kubernetes cluster.  

10) Discussion points

scalability, health check, mounting volume, resource limits, service discovery, deploy with Helm...

11) More resources

eShopOnContainers: https://github.com/dotnet-architecture/eShopOnContainers

https://www.udemy.com/kubernetes-for-developers/ Please email me if you want a free coupon :)