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