Containerizing a .NET Web Application with Docker

This is a step-by-step beginner-friendly guide to containerize a .NET web application using Docker. It includes detailed explanations of Docker commands, Dockerfile, and running the container.

✅ Prerequisites

• .NET SDK (v6.0 or later)
• Docker Desktop
• Code editor (like VS Code)

👣 Step-by-Step Instructions

Step 1: Create a New .NET Web Application

dotnet new webapp -n MyWebApp
cd MyWebApp

Step 2: Run the App Locally

dotnet run

Visit https://localhost:5001 in your browser to verify it's working.

Step 3: Create a Dockerfile

Create a file named Dockerfile in the root directory and paste the following content:

# STEP 1: Build the app
FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
WORKDIR /src
COPY . .
RUN dotnet publish -c Release -o /app/publish

# STEP 2: Run the app
FROM mcr.microsoft.com/dotnet/aspnet:8.0
WORKDIR /app
COPY --from=build /app/publish .
ENTRYPOINT ["dotnet", "MyWebApp.dll"]

Explanation:

• FROM: Specifies the base image.
• WORKDIR: Sets working directory inside the container.
• COPY: Copies files into the container.
• RUN: Executes a command in the container during image build.
• ENTRYPOINT: Command to run when the container starts.

Step 4: Create .dockerignore (Optional)

bin/
obj/
.vscode/
*.md
*.user

Step 5: Build the Docker Image

docker build -t mywebapp .

• build: Tells Docker to build an image.
• -t mywebapp: Tags the image name.
• .: Uses current directory (where Dockerfile is).

Step 6: Run the Docker Container

docker run -d -p 8080:80 --name mywebappcontainer mywebapp

• -d: Runs in detached mode.
• -p 8080:80: Maps local port 8080 to container's port 80.
• --name: Names the container.

Step 7: Manage the Container

Stop the container:

docker stop mywebappcontainer

Remove the container:

docker rm mywebappcontainer

Remove the image:

docker rmi mywebapp

📦 Summary of Docker Commands