This repository contains `Dockerfile` definitions for Docker images that include last-known-good (LKG) builds for the next release of [.NET Core](https://github.com/dotnet/core).
See [dotnet/dotnet-docker](https://github.com/dotnet/dotnet-docker) for images with official releases of [.NET Core](https://github.com/dotnet/core).
>**Note:** The Docker images in this repo are supported by Microsoft. The `arm32v7` images are in preview and have "best effort" support only by the community and .NET Core Team. Please see the [arm32 announcement](https://github.com/dotnet/announcements/issues/29) for more details.
For more information about these images and their history, please see [the relevant Dockerfile (`dotnet/dotnet-docker-nightly`)](https://github.com/dotnet/dotnet-docker-nightly/search?utf8=%E2%9C%93&q=FROM&type=Code). These images are updated via [pull requests to the `dotnet/dotnet-docker-nightly` GitHub repo](https://github.com/dotnet/dotnet-docker-nightly/pulls?utf8=%E2%9C%93&q=).
.NET Core is a general purpose development platform maintained by Microsoft and the .NET community on [GitHub](https://github.com/dotnet/core). It is cross-platform, supporting Windows, macOS and Linux, and can be used in device, cloud, and embedded/IoT scenarios.
.NET has several capabilities that make development easier, including automatic memory management, (runtime) generic types, reflection, asynchrony, concurrency, and native interop. Millions of developers take advantage of these capabilities to efficiently build high-quality applications.
You can use C# to write .NET Core apps. C# is simple, powerful, type-safe, and object-oriented while retaining the expressiveness and elegance of C-style languages. Anyone familiar with C and similar languages will find it straightforward to write in C#.
[.NET Core](https://github.com/dotnet/core) is open source (MIT and Apache 2 licenses) and was contributed to the [.NET Foundation](http://dotnetfoundation.org) by Microsoft in 2014. It can be freely adopted by individuals and companies, including for personal, academic or commercial purposes. Multiple companies use .NET Core as part of apps, tools, new platforms and hosting services.
You can run a [sample application](https://hub.docker.com/r/microsoft/dotnet-samples/) (Linux image) that depends on these images in a container by running the following command.
.NET Core Docker images can use [multi-stage build](https://docs.docker.com/engine/userguide/eng-image/multistage-build/). This feature allows multiple FROM instructions to be used in one Dockerfile. Using this feature, you can build a .NET Core app using an SDK image (AKA 'build image') and then copy the published app into a lighter weight runtime image within a single Dockerfile.
You can check out our [multi-stage build samples](https://github.com/dotnet/dotnet-docker-samples) on GitHub for ASP.NET apps, production scenarios, and self-contained scenarios.
Add a `Dockerfile` to your .NET project with the following:
The `Dockerfile` and the Docker commands assumes that your application is called `dotnetapp`. You can change the `Dockerfile` and the commands, as needed.
You can use the .NET Core SDK Docker image as a build and runtime environment. It's a useful image for iterative development and the easiest way to get started using .NET Core with Docker. It isn't recommended for production since it's a bigger image than necessary, although it can work for that, too. You can try the instructions below or use the [dotnetapp-dev sample](https://github.com/dotnet/dotnet-docker-samples/tree/master/dotnetapp-dev) if you want to try a pre-made version that's ready go.
Create a Dockerfile with following lines, which will both build and run your application in the container. This Dockerfile has been optimized (note the two `COPY` commands) to take advantage of Docker layering, resulting in faster image building for iterative development.
# copy project.json and restore as distinct layers
COPY project.json .
RUN dotnet restore
# copy and build everything else
COPY . .
RUN dotnet publish -c Release -o out
ENTRYPOINT ["dotnet", "out/dotnetapp.dll"]
```
You can then build and run the Docker image:
```console
docker build -t dotnetapp .
docker run -it --rm dotnetapp
```
The `Dockerfile` and the Docker commands assumes that your application is called `dotnetapp`. You can change the `Dockerfile` and the commands, as needed.
You can interactively try out .NET Core by taking advantage of the convenience of a container. Try the following set of commands to create and run a .NET Core application in a minute (depending on your internet speed).
The experience is very similar using [Windows Containers][win-containers]. The commands should be the same, with the exception `ls` and the directory separators.
The steps above are intended to show the basic functions of .NET Core tools. Try running `dotnet run` twice. You'll see that the second invocation skips compilation. The subsequent command after `dotnet run` demonstrates that you can run an application directly out of the bin folder, without the additional build logic that `dotnet run` adds. The last two commands demonstrate the publishing scenario, which prepares an app to be deployed on the same or other machine, with a requirement on only the .NET Core Runtime, not the larger SDK. Naturally, you don't have to exit immediately, but can continue to try out the product as long as you want.
You can extend your interactive exploration of .NET Core by git cloning the [dotnet/dotnet-docker-samples](https://github.com/dotnet/dotnet-docker-samples) repo. Try the following commands (only works on Linux containers), assuming you are running interactively in the container:
## Interactively build and run an ASP.NET Core application
You can interactively try out ASP.NET Core by taking advantage of the convenience of a container. Try the following set of commands to create and run an ASP.NET Core application in a minute (depending on your internet speed).
The experience is very similar using [Windows Containers][win-containers]. The commands should be the same, with the exception of the `docker run`. Replace the `docker run` command above with the following two commands:
Copy the IP address from the output of `ipconfig`. After running `dotnet run` in the container, browse to that IP address in your browser on your host machine.
You should see a default ASP.NET Core site and logging activity in the container.
Please use the images at [microsoft/aspnetcore](https://hub.docker.com/r/microsoft/aspnetcore/). They are recommended and optimized for ASP.NET core development and production and are built on the images in this repo.
See [Building Docker Images for .NET Core Applications](https://docs.microsoft.com/dotnet/core/docker/building-net-docker-images) to learn more about the various Docker images and when to use each for them.
This is the defacto image. If you are unsure about what your needs are, you probably want to use this one. It is designed to be used both as a throw away container (mount your source code and start the container to start your app), as well as the base to build other images off of.
It contains the .NET Core SDK which is comprised of two parts:
This image contains the operating system with all of the native dependencies needed by .NET Core. This is for [self-contained](https://docs.microsoft.com/dotnet/articles/core/deploying/index) applications.
## More Examples using these Images
You can learn more about using .NET Core with Docker with [.NET Docker samples](https://github.com/dotnet/dotnet-docker-samples):
- [.NET Core Development Sample](https://github.com/dotnet/dotnet-docker-samples/tree/master/dotnetapp-dev) - This sample is good for development and building since it relies on the .NET Core SDK image. It performs `dotnet` commands on your behalf, reducing the time it takes to create Docker images (assuming you make changes and then test them in a container, iteratively).
- [.NET Core Docker Production Sample](https://github.com/dotnet/dotnet-docker-samples/tree/master/dotnetapp-prod) - This sample is good for production since it relies on the .NET Core Runtime image, not the larger .NET Core SDK image. Most apps only need the runtime, reducing the size of your application image.
- [.NET Core self-contained application Docker Production Samp](https://github.com/dotnet/dotnet-docker-samples/tree/master/dotnetapp-selfcontained) - This sample is also good for production scenarios since it relies on an operating system image (without .NET Core). [Self-contained .NET Core apps](https://docs.microsoft.com/dotnet/articles/core/deploying/) include .NET Core as part of the app and not as a centrally installed component in a base image.
- [ASP.NET Core Docker Production Sample](https://github.com/dotnet/dotnet-docker-samples/tree/master/aspnetapp) - This samples demonstrates a Dockerized ASP.NET Core Web App.
- [microsoft/aspnetcore](https://hub.docker.com/r/microsoft/aspnetcore/) for ASP.NET Core images.
- [microsoft/aspnet](https://hub.docker.com/r/microsoft/aspnet/) for ASP.NET Web Forms and MVC images.
- [microsoft/dotnet-framework](https://hub.docker.com/r/microsoft/dotnet-framework/) for .NET Framework images (for web applications, see microsoft/aspnet).
The .NET Core Windows container images use the same license as the [Windows Server 2016 Nano Server base image](https://hub.docker.com/r/microsoft/nanoserver/), as follows:
MICROSOFT SOFTWARE SUPPLEMENTAL LICENSE TERMS
CONTAINER OS IMAGE
Microsoft Corporation (or based on where you live, one of its affiliates) (referenced as “us,” “we,” or “Microsoft”) licenses this Container OS Image supplement to you (“Supplement”). You are licensed to use this Supplement in conjunction with the underlying host operating system software (“Host Software”) solely to assist running the containers feature in the Host Software. The Host Software license terms apply to your use of the Supplement. You may not use it if you do not have a license for the Host Software. You may use this Supplement with each validly licensed copy of the Host Software.
If you have any problems with or questions about this image, please contact us through a [GitHub issue](https://github.com/dotnet/dotnet-docker-nightly/issues).
You are invited to contribute new features, fixes, or updates, large or small; we are always thrilled to receive pull requests, and do our best to process them as fast as we can.
Before you start to code, please read the [.NET Core contribution guidelines](https://github.com/dotnet/coreclr/blob/master/CONTRIBUTING.md).
You can read documentation for .NET Core, including Docker usage in the [.NET Core docs](https://docs.microsoft.com/dotnet/core/). The docs are [open source on GitHub](https://github.com/dotnet/core-docs). Contributions are welcome!
