aspnetcore/host-and-deploy/docker/visual-studio-tools-for-docker.md
Visual Studio 2017 or later versions support building, debugging, and running containerized ASP.NET Core apps. Both Windows and Linux containers are supported.
View or download sample code (how to download)
For Docker installation, first review the information at Docker for Windows: What to know before you install. Next, install Docker For Windows.
Shared Drives in Docker for Windows must be configured to support volume mapping and debugging. Right-click the System Tray's Docker icon, select Settings, and select Shared Drives. Select the drive where Docker stores files. Click Apply.
[!TIP] Visual Studio 2017 versions 15.6 or later prompt when Shared Drives aren't configured.
When adding Docker support to a project, choose either a Windows or a Linux container. The Docker host must be running the same container type. To change the container type in the running Docker instance, right-click the System Tray's Docker icon and choose Switch to Windows containers... or Switch to Linux containers....
When creating a new app with the ASP.NET Core Web Application project templates, select the Enable Docker Support checkbox:
The OS drop-down allows for the selection of a container type.
There are two options for adding Docker support to an existing project via the tooling. Open the project in Visual Studio, and choose one of the following options:
The Visual Studio Container Tools don't support adding Docker to an existing ASP.NET Core project targeting .NET Framework.
A Dockerfile, the recipe for creating a final Docker image, is added to the project root. Refer to Dockerfile reference for an understanding of the commands within it. This particular Dockerfile uses a multi-stage build with four distinct, named build stages:
:::moniker range=">= aspnetcore-2.1"
The preceding Dockerfile image includes the ASP.NET Core runtime and NuGet packages. The packages are just-in-time (JIT) compiled to improve startup performance.
When the new project dialog's Configure for HTTPS checkbox is checked, the Dockerfile exposes two ports. One port is used for HTTP traffic; the other port is used for HTTPS. If the checkbox isn't checked, a single port (80) is exposed for HTTP traffic.
:::moniker-end
:::moniker range="<= aspnetcore-2.0"
The preceding Dockerfile image includes the ASP.NET Core NuGet packages, which are just-in-time (JIT) compiled to improve startup performance.
:::moniker-end
Visual Studio 2017 versions 15.7 or earlier support Docker Compose as the sole container orchestration solution. The Docker Compose artifacts are added via Add > Docker Support.
Visual Studio 2017 versions 15.8 or later add an orchestration solution only when instructed. Right-click the project in Solution Explorer and select Add > Container Orchestrator Support. The following choices are available:
The Visual Studio Container Tools add a docker-compose project to the solution with the following files:
<DockerTargetOS> element specifying the OS to be used.docker-compose build and docker-compose run, respectively.docker-compose -f "docker-compose.yml" -f "docker-compose.override.yml" to merge these files.The docker-compose.yml file references the name of the image that's created when the project runs:
In the preceding example, image: hellodockertools generates the image hellodockertools:dev when the app runs in Debug mode. The hellodockertools:latest image is generated when the app runs in Release mode.
Prefix the image name with the Docker Hub username (for example, dockerhubusername/hellodockertools) if the image is pushed to the registry. Alternatively, change the image name to include the private registry URL (for example, privateregistry.domain.com/hellodockertools) depending on the configuration.
If you want different behavior based on the build configuration (for example, Debug or Release), add configuration-specific docker-compose files. The files should be named according to the build configuration (for example, docker-compose.vs.debug.yml and docker-compose.vs.release.yml) and placed in the same location as the docker-compose-override.yml file.
Using the configuration-specific override files, you can specify different configuration settings (such as environment variables or entry points) for Debug and Release build configurations.
For Docker Compose to display an option to run in Visual Studio, the docker project must be the startup project.
In addition to the base Prerequisites, the Service Fabric orchestration solution demands the following prerequisites:
Service Fabric doesn't support running Linux containers in the local development cluster on Windows. If the project is already using a Linux container, Visual Studio prompts to switch to Windows containers.
The Visual Studio Container Tools do the following tasks:
Adds a <project_name>Application Service Fabric Application project to the solution.
Adds a Dockerfile and a .dockerignore file to the ASP.NET Core project. If a Dockerfile already exists in the ASP.NET Core project, it's renamed to Dockerfile.original. A new Dockerfile, similar to the following, is created:
Adds an <IsServiceFabricServiceProject> element to the ASP.NET Core project's .csproj file:
Adds a PackageRoot folder to the ASP.NET Core project. The folder includes the service manifest and settings for the new service.
For more information, see Deploy a .NET app in a Windows container to Azure Service Fabric.
Select Docker from the debug drop-down in the toolbar, and start debugging the app. The Docker view of the Output window shows the following actions taking place:
:::moniker range=">= aspnetcore-2.1"
ASPNETCORE_ENVIRONMENT environment variable is set to Development within the container.docker ps command.The resulting Docker image of the app is tagged as dev. The image is based on the 2.1-aspnetcore-runtime tag of the microsoft/dotnet base image. Run the docker images command in the Package Manager Console (PMC) window. The images on the machine are displayed:
REPOSITORY TAG IMAGE ID CREATED SIZE
hellodockertools dev d72ce0f1dfe7 30 seconds ago 255MB
microsoft/dotnet 2.1-aspnetcore-runtime fcc3887985bb 6 days ago 255MB
:::moniker-end
:::moniker range="<= aspnetcore-2.0"
ASPNETCORE_ENVIRONMENT environment variable is set to Development within the container.docker ps command.The resulting Docker image of the app is tagged as dev. The image is based on the microsoft/aspnetcore base image. Run the docker images command in the Package Manager Console (PMC) window. The images on the machine are displayed:
REPOSITORY TAG IMAGE ID CREATED SIZE
hellodockertools dev 5fafe5d1ad5b 4 minutes ago 347MB
microsoft/aspnetcore 2.0 c69d39472da9 13 days ago 347MB
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[!NOTE] The dev image lacks the app contents, as Debug configurations use volume mounting to provide the iterative experience. To push an image, use the Release configuration.
Run the docker ps command in PMC. Notice the app is running using the container:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
baf9a678c88d hellodockertools:dev "C:\\remote_debugge..." 21 seconds ago Up 19 seconds 0.0.0.0:37630->80/tcp dockercompose4642749010770307127_hellodockertools_1
Changes to static files and Razor views are automatically updated without the need for a compilation step. Make the change, save, and refresh the browser to view the update.
Code file modifications require compilation and a restart of Kestrel within the container. After making the change, use CTRL+F5 to perform the process and start the app within the container. The Docker container isn't rebuilt or stopped. Run the docker ps command in PMC. Notice the original container is still running as of 10 minutes ago:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
baf9a678c88d hellodockertools:dev "C:\\remote_debugge..." 10 minutes ago Up 10 minutes 0.0.0.0:37630->80/tcp dockercompose4642749010770307127_hellodockertools_1
Once the develop and debug cycle of the app is completed, the Visual Studio Container Tools assist in creating the production image of the app. Change the configuration drop-down to Release and build the app. The tooling acquires the compile/publish image from Docker Hub (if not already in the cache). An image is produced with the latest tag, which can be pushed to the private registry or Docker Hub.
Run the docker images command in PMC to see the list of images. Output similar to the following is displayed:
:::moniker range=">= aspnetcore-2.1"
REPOSITORY TAG IMAGE ID CREATED SIZE
hellodockertools latest e3984a64230c About a minute ago 258MB
hellodockertools dev d72ce0f1dfe7 4 minutes ago 255MB
microsoft/dotnet 2.1-sdk 9e243db15f91 6 days ago 1.7GB
microsoft/dotnet 2.1-aspnetcore-runtime fcc3887985bb 6 days ago 255MB
:::moniker-end
:::moniker range="<= aspnetcore-2.0"
REPOSITORY TAG IMAGE ID CREATED SIZE
hellodockertools latest cd28f0d4abbd 12 seconds ago 349MB
hellodockertools dev 5fafe5d1ad5b 23 minutes ago 347MB
microsoft/aspnetcore-build 2.0 7fed40fbb647 13 days ago 2.02GB
microsoft/aspnetcore 2.0 c69d39472da9 13 days ago 347MB
The microsoft/aspnetcore-build and microsoft/aspnetcore images listed in the preceding output are replaced with microsoft/dotnet images as of .NET Core 2.1. For more information, see the Docker repositories migration announcement.
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[!NOTE] The
docker imagescommand returns intermediary images with repository names and tags identified as <none> (not listed above). These unnamed images are produced by the multi-stage build Dockerfile. They improve the efficiency of building the final image—only the necessary layers are rebuilt when changes occur. When the intermediary images are no longer needed, delete them using the docker rmi command.
There may be an expectation for the production or release image to be smaller in size by comparison to the dev image. Because of the volume mapping, the debugger and app were running from the local machine and not within the container. The latest image has packaged the necessary app code to run the app on a host machine. Therefore, the delta is the size of the app code.