# Dotnet {#dotnet}

## Local Development Workflow {#local-development-workflow}

For local development, it's recommended to use nix-shell to create a dotnet environment:

```nix
# shell.nix
with import <nixpkgs> { };

mkShell {
  name = "dotnet-env";
  packages = [
    dotnet-sdk
  ];
}
```

### Using many sdks in a workflow {#using-many-sdks-in-a-workflow}

It's very likely that more than one sdk will be needed on a given project. Dotnet provides several different frameworks (E.g dotnetcore, aspnetcore, etc.) as well as many versions for a given framework. Normally, dotnet is able to fetch a framework and install it relative to the executable. However, this would mean writing to the nix store in nixpkgs, which is read-only. To support the many-sdk use case, one can compose an environment using `dotnetCorePackages.combinePackages`:

```nix
with import <nixpkgs> { };

mkShell {
  name = "dotnet-env";
  packages = [
    (
      with dotnetCorePackages;
      combinePackages [
        sdk_8_0
        sdk_9_0
      ]
    )
  ];
}
```

This will produce a dotnet installation that has the dotnet 8.0 9.0 sdk. The first sdk listed will have it's cli utility present in the resulting environment. Example info output:

```ShellSession
$ dotnet --info
.NET SDK:
 Version:           9.0.100
 Commit:            59db016f11
 Workload version:  9.0.100-manifests.3068a692
 MSBuild version:   17.12.7+5b8665660

Runtime Environment:
 OS Name:     nixos
 OS Version:  25.05
 OS Platform: Linux
 RID:         linux-x64
 Base Path:   /nix/store/a03c70i7x6rjdr6vikczsp5ck3v6rixh-dotnet-sdk-9.0.100/share/dotnet/sdk/9.0.100/

.NET workloads installed:
There are no installed workloads to display.
Configured to use loose manifests when installing new manifests.

Host:
  Version:      9.0.0
  Architecture: x64
  Commit:       9d5a6a9aa4

.NET SDKs installed:
  8.0.404 [/nix/store/6wlrjiy10wg766490dcmp6x64zb1vc8j-dotnet-core-combined/share/dotnet/sdk]
  9.0.100 [/nix/store/6wlrjiy10wg766490dcmp6x64zb1vc8j-dotnet-core-combined/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 8.0.11 [/nix/store/6wlrjiy10wg766490dcmp6x64zb1vc8j-dotnet-core-combined/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 9.0.0 [/nix/store/6wlrjiy10wg766490dcmp6x64zb1vc8j-dotnet-core-combined/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 8.0.11 [/nix/store/6wlrjiy10wg766490dcmp6x64zb1vc8j-dotnet-core-combined/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 9.0.0 [/nix/store/6wlrjiy10wg766490dcmp6x64zb1vc8j-dotnet-core-combined/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
  None

Environment variables:
  Not set

global.json file:
  Not found

Learn more:
  https://aka.ms/dotnet/info

Download .NET:
  https://aka.ms/dotnet/download
```

## dotnet-sdk vs dotnetCorePackages.sdk {#dotnet-sdk-vs-dotnetcorepackages.sdk}

The `dotnetCorePackages.sdk_X_Y` is preferred over the old dotnet-sdk as both major and minor version are very important for a dotnet environment. If a given minor version isn't present (or was changed), then this will likely break your ability to build a project.

## dotnetCorePackages.sdk vs dotnetCorePackages.runtime vs dotnetCorePackages.aspnetcore {#dotnetcorepackages.sdk-vs-dotnetcorepackages.runtime-vs-dotnetcorepackages.aspnetcore}

The `dotnetCorePackages.sdk` contains both a runtime and the full sdk of a given version. The `runtime` and `aspnetcore` packages are meant to serve as minimal runtimes to deploy alongside already built applications.

## Packaging a Dotnet Application {#packaging-a-dotnet-application}

To package Dotnet applications, you can use `buildDotnetModule`. This has similar arguments to `stdenv.mkDerivation`, with the following additions:

* `projectFile` is used for specifying the dotnet project file, relative to the source root. These have `.sln` (entire solution) or `.csproj` (single project) file extensions. This can be a list of multiple projects as well. When omitted, will attempt to find and build the solution (`.sln`). If running into problems, make sure to set it to a file (or a list of files) with the `.csproj` extension - building applications as entire solutions is not fully supported by the .NET CLI.