biswabandhu21 / customerapp

A simple customer database for a fictitious company. Kubernetes + Java backed by MongoDB. Makes heavy use of Microsoft managed services to keep things easy.

Summary

A simple customer database for a fictitious company. Kubernetes + Java backed by MongoDB. Makes heavy use of Microsoft managed services to keep things easy. Traffic to/from the application is secured using TLS.

This is a demonstration application that optimizes for simplicity and learning. Not intended for production use.

Prerequisites

• A Microsoft Azure account, for running Kubernetes (AKS) and MongoDB (CosmosDB)
• A Docker Hub account, for storing our application image.
• A Lets Encrypt account
• A domain name you control, for making the application available to the world

Setup

Provisioning the initial resources can take a little time so I did these steps upfront.

1. Download and setup the command-line tools you'll need on your computer. The examples below assume Mac but should work on other platforms.

• Docker for Mac. Choose the Edge version if you want experimental Kubernetes support (not required)
• Azure CLI
• Kubectl
• Helm

2. Create an Azure group and an empty Kubernetes cluster in that group

az group create --name bayazure --location eastus
az aks create --name k8s --resource-group bayazure
az aks get-credentials --name k8s --resource-group bayazure

3. Add some needed components to Kubernetes

$ helm init
$ helm install stable/nginx-ingress
$ helm install --name kube-lego stable/kube-lego --set [email protected] --set config.LEGO_URL=https://acme-v01.api.letsencrypt.org/directory

We use nginx-ingress to route external traffic within our cluster. kube-lego is used to automatically obtain a TLS certificate from Let's Encrypt. Adjust the example values above for your environment and domain.

4. Next we'll create a CosmosDB MongoDB database to store our application data in.

$ az cosmosdb create --kind MongoDB --name customerdatabase --resource-group bayazure

Building and deploying the application

5. First create a Kubernetes secret so that the application can connect to MongoDB:

kubectl create secret generic customerdatabasesecret \
    --from-literal="MONGODB_URI=$(\
    az cosmosdb list-connection-strings -n customerdatabase -g bayazure --query "connectionStrings[0].connectionString" \
      --out tsv | tr -d '\n')"

6. Next we'll build our Spring Boot application code:

mvn clean package

This creates an file target/customerapp-0.1.2.war that contains our application.

7. Then package the application in a Container image and push it to the Docker Hub:

docker build -t nomisbeme/customerapp:0.1.2 .
docker push nomisbeme/customerapp:0.1.2

8. Use the Kubernetes package manager, helm, to deploy the resulting application to Kubernetes.

helm install helm/customerapp/ -n capp

Adjust the ingress.host to point to the correct domain name if needed.

9. Wait for the application to deploy then access it at your domain name.

open http://azure.baleenlabs.com

Updating the application

Kubernetes and Helm make it easy to deploy new versions of an application, so we'll modify the application and deploy the result.

10. Modify the application. Hint: Uncomment list.jsp

11. Rebuild the application and push a new version to the Docker Hub:

mvn clean package
docker build -t nomisbeme/customerapp:fixed .
docker push nomisbeme/customerapp:fixed

12. Now update the existing deployment to reference the new code.

helm upgrade --set image.tag=fixed capp helm/customerapp

Improvements

• Use Open Service Catalog for Azure to expose Cosmos within the Kubernetes cluster
• Use the Spotify maven plugins to simplify container image creation
• Use a private registry e.g. Azure Container Registry to avoid making application code publicly available.
• Replace kube-lego with the more modern replacement cert-manager