Quickstart: Docker in Visual Studio

Applies to: Visual Studio Visual Studio for Mac Visual Studio Code

With Visual Studio, you can easily build, debug, and run containerized .NET, ASP.NET, and ASP.NET Core apps and publish them to Azure Container Registry, Docker Hub, Azure App Service, or your own container registry. In this article, we'll publish an ASP.NET Core app to Azure Container Registry.

Prerequisites

• Docker Desktop
• Visual Studio 2022 with the Web Development, Azure Tools workload, and/or .NET Core cross-platform development workload installed
• .NET Core Development Tools for development with .NET Core
• To publish to Azure Container Registry, an Azure subscription. Sign up for a free trial.

Installation and setup

For Docker installation, first review the information at Docker Desktop for Windows: What to know before you install. Next, install Docker Desktop.

Add a project to a Docker container

1. Create a new project using the ASP.NET Core Web App template or if you want to use the .NET Framework instead of .NET Core, choose ASP.NET Web Application (.NET Framework).

2. On the Create new web application screen, make sure the Enable Docker Support checkbox is selected.

   

   The screenshot shows .NET 6.0; if you're using .NET Framework, it looks a bit different.

3. Select the type of container you want (Windows or Linux) and click Create.

Dockerfile overview

A Dockerfile, the recipe for creating a final Docker image, is created in the project. Refer to Dockerfile reference for an understanding of the commands within it:

#See https://aka.ms/containerfastmode to understand how Visual Studio uses this Dockerfile to build your images for faster debugging.

FROM mcr.microsoft.com/dotnet/aspnet:6.0 AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

FROM mcr.microsoft.com/dotnet/sdk:6.0 AS build
WORKDIR /src
COPY ["WebApplication3/WebApplication3.csproj", "WebApplication3/"]
RUN dotnet restore "WebApplication3/WebApplication3.csproj"
COPY . .
WORKDIR "/src/WebApplication3"
RUN dotnet build "WebApplication3.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "WebApplication3.csproj" -c Release -o /app/publish

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "WebApplication3.dll"]

The preceding Dockerfile is based on the Microsoft Container Registry (MCR) .NET 6 image image, and includes instructions for modifying the base image by building your project and adding it to the container. If you're using the .NET Framework, the base image will be different.

When the new project dialog's Configure for HTTPS check box is checked, the Dockerfile exposes two ports. One port is used for HTTP traffic; the other port is used for HTTPS. If the check box isn't checked, a single port (80) is exposed for HTTP traffic.

Debug

Select Docker from the debug drop-down in the toolbar, and start debugging the app. You might see a message with a prompt about trusting a certificate; choose to trust the certificate to continue.

The Container Tools option in the Output window shows what actions are taking place. The first time, it might take a while to download the base image, but it's much faster on subsequent runs.

After building, the browser comes up and your app's home page is shown. In the browser's address bar, you can see the localhost URL and port number for debugging.

Note

If you need to change ports for debugging, you can do that in the launchSettings.json file. See Container Launch Settings.

Containers window

You can use the Containers window to view running containers on your machine, as well as images that you have available.

Open the Containers window by using the search box in the IDE (press Ctrl+Q to use it), type in container, and choose the Containers window from the list.

You can mount the Containers window in a convenient place, such as below the editor, by moving it around and following the window placement guides.

In the window, find your container and step through each tab to view the environment variables, port mappings, logs, and the filesystem.

For more information, see Use the Containers window.

Publish Docker images

Once the develop and debug cycle of the app is completed, you can create a production image of the app.

1. Change the configuration drop-down to Release and build the app.

2. Right-click your project in Solution Explorer and choose Publish.

3. On the Publish dialog, select the Docker Container Registry tab.

   

4. Choose Create New Azure Container Registry.

   

5. Fill in your desired values in the Create a new Azure Container Registry.

   Setting	Suggested value	Description
   DNS Prefix	Globally unique name	Name that uniquely identifies your container registry.
   Subscription	Choose your subscription	The Azure subscription to use.
   Resource Group	myResourceGroup	Name of the resource group in which to create your container registry. Choose New to create a new resource group.
   SKU	Standard	Service tier of the container registry
   Registry Location	A location close to you	Choose a Location in a region near you or near other services that will use your container registry.

   

6. Click Create. The Publish dialog now shows the created registry.

   

7. Choose Finish to complete the process of publishing your container image to the newly created registry in Azure.

   

Next steps

You can now pull the container from the registry to any host capable of running Docker images, for example Azure Container Instances.

Additional resources

• Container development with Visual Studio
• Troubleshoot Visual Studio development with Docker
• Visual Studio Container Tools GitHub repository