ASP.NET Core in a Container

Here's a simple example for getting an ASP.NET Core project running in a Docker container.

This was created to teach the core concepts of Docker.

Definitions:

• Dockerfile: A manifest file that describes your Docker Image.
• Docker Image: The output of a build of your Dockerfile. Use docker build command to create a Docker Image.
• Docker Container: An runtime instance of your Docker Image. Use docker run to start a new container instance.

Pre-reqs

1. Install .NET Core SDK: https://www.microsoft.com/net/core#windowscmd
2. Install Docker: https://docs.docker.com/engine/installation/

• If you are running Windows, switch to Windows containers.

Just Run the Sample

To just run the sample:

1. Clone this repo
2. Run build.cmd in the root.

The build.cmd file will build the aspnetcore project, copy the output to ./publish folder, build the Docker Image and run the Docker Container.

3. Copy and Paste the outputted IP address into a browser.

You will see "Hello World" - an ASP.NET Core site hosted in a container!

Build the Sample from Scratch

Follow these instructions to create this sample from scratch.

1. Create New Folder

Open a command prompt and execute the following:

mkdir aspnetcorecontainer

2. Create New Core Web Project

dotnet new web

3. Restore Dependencies

dotnet restore

4. Run Site

dotnet run

5. Load Site

http://localhost:5000

6. Create Dockerfile

This will use the aspnetcore image and copy the files from publish to the /app directory and then configure the dotnet entrypoint to the dll.

FROM microsoft/aspnetcore
WORKDIR /app
COPY ./publish .
ENTRYPOINT ["dotnet", "aspnetcorecontainer.dll"]

7. Build and Publish Site

dotnet build
dotnet publish -o ./publish

8. Build Container Image

docker build -t aspnetcore-image .

9. Run Container

docker run -d -p 8000:80 --name aspnetcore-container aspnetcore-image

10. Get Container IP Address

docker inspect -f "{{ .NetworkSettings.Networks.nat.IPAddress }}" aspnetcore-container

11. Load Site

Load the IP address returned in the previous step in a browser

12. Connect to Container's Powershell Prompt

To show that the container is running in an isolated space, we are going to see the process count difference between the container and the host machine.

docker exec -ti aspnetcore-container powershell

13. Get Container Process Count

From the container's PowerShell prompt:

(Get-Process).Count

14. Get Host Machine Process Count

If you are in cmd, run the following:

powershell (Get-Process).Count

If you are in a PS prompt, run the following:

(Get-Process).Count

Clean Up

Execute the following command to remove the container before you re-run these steps.

docker rm /aspnetcore-container -f