C# Rules for Bazel

• Buildkite:

  

• Azure pipelines

  

Contents

• Documentation
• Overview
• Caveats
• Setup
• Examples

Documentation

• Core API
  • dotnet_library
  • dotnet_binary
  • dotnet_nunit_test
  • dotnet_resx
  • dotnet_import_library
• Workspace rules
• Toolchains
• Tests

Overview

This is a minimal viable set of C# bindings for building C# code with Mono. It's still pretty rough but it works as a proof of concept that could grow into something more.

Caveats

These rules are not compatible with sandboxing. Particularly, running dotnet rules on linux o macos requires passing --spawn_strategy=standalone.

Bazel creates long paths. Therefore it is recommended to increase the length limit using newer version of Windows. Please see here.

However, some Windows programs do not handle long path names. Most notably - Microsoft cl compiler. Therefore TMP env variable should be set to something short (like X:\ or c:\TEMP).

Bazel and dotnet rules rely on symbolic linking. On Windows it, typically, requires elevated permissions. However, newer versions of Windows hava a workaround.

NUnit v2 runner used in some tests requires .NET Framework 3.5 installation.

Setup

• Add the following to your WORKSPACE file to add the external repositories:

  # A newer version should be fine
  git_repository(
      name = "io_bazel_rules_dotnet",
      remote = "https://github.com/bazelbuild/rules_dotnet",
      tag = "0.0.2",
  )
  
  load("@io_bazel_rules_dotnet//dotnet:defs.bzl", "dotnet_register_toolchains", "dotnet_repositories")
  
  dotnet_register_toolchains("host")
  
  dotnet_repositories()

  The dotnet_repositories rule fetches external dependencies, namely the nuget binary. The dotnet_register_toolchains tries to locate mono binaries and configure toolchains to use it. Support for downloading mono is coming soon.

• Add a file named BUILD.bazel in the root directory of your project. In general, you need one of these files in every directory with dotnet code. At the top of the file used rules should be imported:

  load("@io_bazel_rules_dotnet//dotnet:defs.bzl", "dotnet_library", "dotnet_binary")

• If you intend to use CoreCLR make sure to install libunwind-devel if it is not present on your system (applies to Linux).

Examples

• dotnet_library

  dotnet_library(
    name = "foo_bar",
    srcs = [
        "foo.cs",
        "bar.cs",
    ],
    deps = [
        "//examples/example_lib:MyClass",
        "@npgsql//:npgsqllib",
    ],
    visibility = ["//visibility:public"],
  )

• dotnet_binary

  dotnet_binary(
    name = "foo_bar",
    srcs = [
        "foo.cs",
        "bar.cs",
    ],
    deps = [
        "//examples/example_lib:MyClass",
        "@npgsql//:npgsqllib",
    ],
    visibility = ["//visibility:public"],
  )

• dotnet_nunit_test

  dotnet_nunit_test(
      name = "MyTest",
      srcs = [
          "MyTest.cs",
      ],
      deps = [
          "//examples/example_lib:MyClass",
          "//dotnet/externals/nunit2:nunit.framework",
      ],
  )

• dotnet_resx

  dotnet_resx(
      name = "Transform",
      src = "//dotnet/externals/nunit2/nunitv2:src/ClientUtilities/util/Transform.resx",
  )

• nuget_package

  In the WORKSPACE file for your project record a nuget dependency like so. This is a repository rule so it will not work unless it is in a workspace file.

  nuget_package(
      name = "newtonsoft.json",
      package = "newtonsoft.json",
      version = "11.0.2",
      sha256 = "679e438d5eb7d7e5599aa71b65fd23ee50dabf57579607873b87d34aec11ca1e",
      core_lib = "lib/netstandard2.0/Newtonsoft.Json.dll",
      net_lib = "lib/net45/Newtonsoft.Json.dll",
      mono_lib = "lib/net45/Newtonsoft.Json.dll",
      core_deps = [
      ],
      net_deps = [
      ],
      mono_deps = [
      ],
      core_files = [
          "lib/netstandard2.0/Newtonsoft.Json.dll",
          "lib/netstandard2.0/Newtonsoft.Json.xml",
      ],
      net_files = [
          "lib/net45/Newtonsoft.Json.dll",
          "lib/net45/Newtonsoft.Json.xml",
      ],
      mono_files = [
          "lib/net45/Newtonsoft.Json.dll",
          "lib/net45/Newtonsoft.Json.xml",
      ],
  )

  Now, in a BUILD file, you can add the package to your deps

  dotnet_binary(
      name = "foo_bar",
      srcs = [
          "foo.cs",
          "bar.cs",
      ],
      deps = [
          "//examples/example_lib:MyClass",
          "@newtonsoft.json//:dotnet",
      ],
      visibility = ["//visibility:public"],
  )

• dotnet_nuget_new

  In the WORKSPACE file for your project record a nuget dependency like so. This is a repository rule so it will not work unless it is in a workspace file.

  dotnet_nuget_new(
          name = "npgsql",
          package="Npgsql",
          version="3.2.7",
          sha256="fa3e0cfbb2caa9946d2ce3d8174031a06320aad2c9e69a60f7739b9ddf19f172",
          build_file_content = """
      package(default_visibility = [ "//visibility:public" ])
      load("@io_bazel_rules_dotnet//dotnet:defs.bzl", "dotnet_import_library")
  
      dotnet_import_library(
          name = "npgsqllib",
          src = "lib/net451/Npgsql.dll"
      )
          """
  )

  Now, in a BUILD file, you can add the package to your deps:

  dotnet_binary(
      name = "foo_bar",
      srcs = [
          "foo.cs",
          "bar.cs",
      ],
      deps = [
          "//examples/example_lib:MyClass",
          "@npgsql//:npgsqllib",
      ],
      visibility = ["//visibility:public"],
  )