Dockerize .NET Core apps - (ASP.NET Core Docker)

In this tutorial, we will learn how to containerize an ASP.NET Core application using Docker. Docker is an open-source containerization technology that enables you to package your applications into containers, making them easy to deploy and run consistently in different environments.

Prerequisites

To follow along with this tutorial, you will need:

• An ASP.NET Core application (we will be using a sample application)
• Docker (Install from here)
• A basic understanding of how to work with Docker

Step-by-Step Guide

Step 1: Create an ASP.NET Core application

If you already have an ASP.NET Core application, you can skip to the next step. If not, then create a new project using the following command:

dotnet new webapp -o aspnetcore-docker-sample

Step 2: Add Docker support to your application

The next step is to add Docker support to your application. You can do this by using Visual Studio or by manually adding the Dockerfile to your application.

Method 1: Adding Docker support using Visual Studio

1. Open your solution in Visual Studio.
2. Right-click on the project, and select Add > Container Orchestrator Support.
3. In the Add Container Orchestrator Support dialog box, select Docker Compose, and click Add.

Visual Studio will automatically add a Dockerfile and a docker-compose.yml file to your project.

Method 2: Adding Docker support manually

1. Create a new file in the root of your project called Dockerfile.
2. Open the Dockerfile in a text editor, and add the following code:

FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS build-env
WORKDIR /app

COPY *.csproj .
RUN dotnet restore "aspnetcore-docker-sample.csproj"
COPY . .

RUN dotnet publish "aspnetcore-docker-sample.csproj" -c Release -o out

FROM mcr.microsoft.com/dotnet/core/aspnet:3.1
WORKDIR /app
COPY --from=build-env /app/out .
ENTRYPOINT ["dotnet", "aspnetcore-docker-sample.dll"]

Step 3: Build and run the Docker container

To build and run the Docker container, follow these steps:

1. Open a terminal window, and navigate to the root of your application.

2. Run the following command to build the Docker container:

   docker build -t myapp .
   

   This will build a Docker image with the tag myapp.

3. Once the build is complete, run the following command to start the container:

   docker run -p 8080:80 myapp
   

   This will start the container and map port 8080 on your local machine to port 80 in the container.

4. Open your web browser, and navigate to http://localhost:8080. You should see your ASP.NET Core application running inside a Docker container.

Step 4: Stop and remove the container

To stop and remove the container, follow these steps:

1. In the terminal window, press Ctrl-C to stop the container.

2. Run the following command to remove the container:

   docker ps -a
   

   This will list all the containers running on your local machine.

3. Find the ID of the container you want to remove, and run the following command:

   docker rm <container-id>
   

   This will remove the container from your local machine.

Explanation

In this tutorial, we learned how to containerize an ASP.NET Core application using Docker. We created a Dockerfile for our application, built a Docker image, and ran a container based on that image. We also saw how to map ports between the host machine and the container.

Using Docker, we can package our applications into containers, making them easy to deploy and run consistently in different environments. This makes it easier to move our applications between development, testing, and production environments, without having to worry about dependencies or compatibility issues.

Important Points

• To containerize an ASP.NET Core application using Docker, you need to create a Dockerfile.
• You can build a Docker image using the docker build command.
• You can run a Docker container using the docker run command.
• You can map ports between the host machine and the container using the -p option.

Summary

In this tutorial, we learned how to containerize an ASP.NET Core application using Docker. We started by creating a new ASP.NET Core application, added Docker support to it, built a Docker image, and ran a container based on that image. We also saw how to stop and remove the container. By packaging our applications into containers, we can make them easier to deploy and run consistently in different environments.