Purpose

Demonstrate use of ConfigMap feature in a sample ASP.Net WebAPI is hosted into Kubernetes running using DockerDesktop.

• Shows how environment variables can be injected from yml file.
• Shows how appsettings.json file can be injected from yml file.

Environment

• ASP.Net WebAPI on .Net 5
• Docker Desktop
• Windows 10
• Visual Studio 2019

How to run

• Clone.
• Compile the project and make sure its running using Docker.
• Build the docker image
  • Use the below command from the solution folder
  • docker build -t simplek8sconfigmap -f .\host\Dockerfile .
• Tag the image with our user name and repository
• Push the newly created image to your docker image registry.
  • The sample uses Docker Hub for images
• Change the yml files with your docker user id and registry.

Scenario 1 - Injecting env variable

• Apply the file k8s-docker-desktop-env-var-deploy.yml using kubectl
• Get the list of services in the deployment and get the NodePort number
• Navigate to http://localhost:/Echo

It will show the EnvVars object in the response

Scenario 2 - Injecting app.settings file as mount

• Apply the file k8s-docker-desktop-app-settings-deploy.yml using kubectl
• Get the list of services in the deployment and get the NodePort number
• Navigate to http://localhost:/Configurations/MyKey

It will show the injected value MyKey: My value from appsettings.json available in source code in the response

Points to note

• The K8s yml files are targeted to deploy into local dev environments that run using Docker Desktop
• If it needs to be deployed to cloud such as Azure the service needs to use LoadBalancer instead of NodePort
• The container expose 443 and 80 ports. But the K8s yaml file uses only port 80. This is on the assumption that with in K8s cluster pods/containers can communicate without http(s)
  • Enabling http(s) requires certificate and that is not in the scope of this PoC