buildDotnetModule: add documentation

doc/languages-frameworks/dotnet.section.md

@@ -70,6 +70,40 @@ The `dotnetCorePackages.sdk` contains both a runtime and the full sdk of a given
 
 ## Packaging a Dotnet Application {#packaging-a-dotnet-application}
 
-Ideally, we would like to build against the sdk, then only have the dotnet runtime available in the runtime closure.
+To package Dotnet applications, you can use `buildDotnetModule`. This has similar arguments to `stdenv.mkDerivation`, with the following additions:
 
-TODO: Create closure-friendly way to package dotnet applications
+* `projectFile` has to be used for specifying the dotnet project file relative to the source root. These usually have `.sln` or `.csproj` file extensions.
+* `nugetDeps` has to be used to specify the NuGet dependency file. Unfortunately, these cannot be deterministically fetched without a lockfile. This file should be generated using `nuget-to-nix` tool, which is available in nixpkgs.
+* `executables` is used to specify which executables get wrapped to `$out/bin`, relative to `$out/lib/$pname`. If this is unset, all executables generated will get installed. If you do not want to install any, set this to `[]`.
+* `runtimeDeps` is used to wrap libraries into `LD_LIBRARY_PATH`. This is how dotnet usually handles runtime dependencies.
+* `buildType` is used to change the type of build. Possible values are `Release`, `Debug`, etc. By default, this is set to `Release`.
+* `dotnet-sdk` is useful in cases where you need to change what dotnet SDK is being used.
+* `dotnet-runtime` is useful in cases where you need to change what dotnet runtime is being used.
+* `dotnetRestoreFlags` can be used to pass flags to `dotnet restore`.
+* `dotnetBuildFlags` can be used to pass flags to `dotnet build`.
+* `dotnetInstallFlags` can be used to pass flags to `dotnet install`.
+* `dotnetFlags` can be used to pass flags to all of the above phases.
+
+Here is an example `default.nix`, using some of the previously discussed arguments:
+```nix
+{ lib, buildDotnetModule, dotnetCorePackages, ffmpeg }:
+
+buildDotnetModule rec {
+  pname = "someDotnetApplication";
+  version = "0.1";
+
+  src = ./.;
+
+  projectFile = "src/project.sln";
+  nugetDeps = ./deps.nix; # File generated with `nuget-to-nix path/to/src > deps.nix`.
+
+  dotnet-sdk = dotnetCorePackages.sdk_3_1;
+  dotnet-runtime = dotnetCorePackages.net_5_0;
+  dotnetFlags = [ "--runtime linux-x64" ];
+
+  executables = [ "foo" ]; # This wraps "$out/lib/$pname/foo" to `$out/bin/foo`.
+  executables = []; # Don't install any executables.
+
+  runtimeDeps = [ ffmpeg ]; # This will wrap ffmpeg's library path into `LD_LIBRARY_PATH`.
+}
+```

doc/languages-frameworks/index.xml

@@ -12,6 +12,7 @@
  <xi:include href="coq.section.xml" />
  <xi:include href="crystal.section.xml" />
  <xi:include href="dhall.section.xml" />
+ <xi:include href="dotnet.section.xml" />
  <xi:include href="emscripten.section.xml" />
  <xi:include href="gnome.section.xml" />
  <xi:include href="go.section.xml" />