Grpc.Tools: Customize path to gRPC codegen plugin via Environment Variable

[mleutner]

Is your feature request related to a problem? Please describe.

Provide an environment variable to specify a custom path to gRPC plugin executable (gRPC_PluginFullPath) for csharp. While there is a environment variable and configuration capabilities for protoc (via export PROTOBUF_PROTOC=</path/to/protoc>, there is non comprehensive way for RPC_Plugin (e.g. /path/to/grpc_csharp_plugin).
This FR is related to the lack of linux-musl_x64 target support and the resulting issue #24188 "Grpc.Tools generation doesn't work in alpine".

Describe the solution you'd like

In _Grpc.Tools.targets provide configuration for a custom environment variable to specify a path to the grpc_csharp_plugin, see TODO(kkm).

Describe alternatives you've considered

An alternative would be to support and distribute linux-musl_x64 targets with Grpc.Tools

Additional context

Alpine is widely used and also one of the supported targets of Microsoft .NET

[jtattermusch]

FTR

grpc/src/csharp/Grpc.Tools/build/_protobuf/Google.Protobuf.Tools.targets

Line 73 in 7e532fd

<Protobuf_ProtocFullPath Condition=" '$(Protobuf_ProtocFullPath)' == '' ">$(PROTOBUF_PROTOC)</Protobuf_ProtocFullPath>

grpc/src/csharp/Grpc.Tools/build/_grpc/_Grpc.Tools.targets

Line 25 in 7e532fd

<gRPC_PluginFullPath Condition=" '$(gRPC_PluginFullPath)' == '' and '$(Protobuf_ToolsOs)' == 'windows' "

[jtattermusch]

@mleutner would you be open to creating a PR that adds the configuration point?

[tonydnewell]

Added PR #30411

Added environment variable GRPC_TOOL_PLUGIN to override the grpc_csharp_plugin location/executable

[tonydnewell]

Renamed the env variable to GRPC_PROTOC_PLUGIN

[cwhsu1984]

yesterday I upgrade my project from net6 to net7 and getting this error when doing dotnet test
my image is dotnet/sdk:7.0.100-alpine3.16-amd64

the command that gets error

    - dotnet restore
    - apk update
      && apk --no-cache add protobuf grpc
      && path="$(dirname "$(find /root/.nuget/packages/grpc.tools -type d -name linux_x64 | head -1)")"
      && ln -sf /usr/bin/protoc $path/linux_x64/protoc
      && ln -sf /usr/bin/grpc_csharp_plugin $path/linux_x64/grpc_csharp_plugin
    - dotnet test /p:CollectCoverage=true /p:CoverletOutputFormat=opencover /p:CoverletOutput=./coverage/ ./$PROJECT_NAME.UnitTests --no-restore

the error shows

/root/.nuget/packages/grpc.tools/2.49.0/build/_protobuf/Google.Protobuf.Tools.targets(280,5): error MSB6003:
The specified task executable "/root/.nuget/packages/grpc.tools/2.49.0/tools/linux_x64/protoc" could not be run. System.ComponentModel.Win32Exception (2): An error occurred trying to start process 
'/root/.nuget/packages/grpc.tools/2.49.0/tools/linux_x64/protoc' with working directory '/path/to/myporj'. No such file or 
directory [/path/to/myporj/myporj.csproj]

Is this due to the same reason?

[tonydnewell]

@cwhsu1984 This looks the same as #24188 - see that issue for workarounds

The issue you've commented on here enables a workaround by letting you to set the GRPC_PROTOC_PLUGIN environment variable to point to your own protoc plugin that has been built to work on Alpine. Again - see #24188

[cwhsu1984]

I try belows but failed for the same reason, any suggestion?

use script

script:
    - dotnet restore 
    - apk update
      && apk --no-cache add protobuf grpc
      && path="$(dirname "$(find /root/.nuget/packages/grpc.tools -type d -name linux_x64 | head -1)")"
      && ln -sf /usr/bin/protoc $path/linux_x64/protoc
      && ln -sf /usr/bin/grpc_csharp_plugin $path/linux_x64/grpc_csharp_plugin
    - export GRPC_PROTOC_PLUGIN=$path/linux_x64/grpc_csharp_plugin
    - dotnet test /p:CollectCoverage=true /p:CoverletOutputFormat=opencover /p:CoverletOutput=./coverage/ ./$PROJECT_NAME.UnitTests.csproj --no-restore

use before_script

before_script:
     - apk update
       && apk --no-cache add protobuf grpc
       && path="$(dirname "$(find /root/.nuget/packages/grpc.tools -type d -name linux_x64 | head -1)")"
       && ln -sf /usr/bin/protoc $path/linux_x64/protoc
       && ln -sf /usr/bin/grpc_csharp_plugin $path/linux_x64/grpc_csharp_plugin
     - export GRPC_PROTOC_PLUGIN=$path/linux_x64/grpc_csharp_plugin
script:
     - dotnet restore
     - dotnet test /p:CollectCoverage=true /p:CoverletOutputFormat=opencover /p:CoverletOutput=./coverage/ ./$PROJECT_NAME.UnitTests.csproj --no-restore

[tonydnewell]

@cwhsu1984 Make sure you have Grpc.Tools version 2.50.0 or later
Also you may want to set PROTOBUF_PROTOC to point to the protoc executable (see #27099 (comment))

[cwhsu1984]

@tonydnewell after doing what you told me, my unit tests work now, thanks!

To sum up,

• upgrade Grpc.Tools 2.50.0
• export PROTOBUF_PROTOC and GRPC_PROTOC_PLUGIN

belows are modified script that works for me

  script:
    - dotnet restore
    - apk update
      && apk --no-cache add protobuf grpc
      && path="$(dirname "$(find /root/.nuget/packages/grpc.tools -type d -name linux_x64 | head -1)")"
      && ln -sf /usr/bin/protoc $path/linux_x64/protoc
      && ln -sf /usr/bin/grpc_csharp_plugin $path/linux_x64/grpc_csharp_plugin
    - export PROTOBUF_PROTOC=$path/linux_x64/protoc
    - export GRPC_PROTOC_PLUGIN=$path/linux_x64/grpc_csharp_plugin
    - dotnet test /p:CollectCoverage=true /p:CoverletOutputFormat=opencover /p:CoverletOutput=./coverage/ ./$PROJECT_NAME.UnitTests.csproj --no-restore

[vahpetr]

I got the some error on M1 docker build. Also you write something like as:

# Dockerfile
FROM mcr.microsoft.com/dotnet/sdk:7.0-alpine AS builder
RUN apk update --no-cache && apk upgrade --no-cache
RUN apk add --no-cache ca-certificates wget
RUN wget -q -O /etc/apk/keys/sgerrand.rsa.pub https://alpine-pkgs.sgerrand.com/sgerrand.rsa.pub
RUN wget https://github.com/sgerrand/alpine-pkg-glibc/releases/download/2.35-r0/glibc-2.35-r0.apk
RUN apk add --no-cache --force-overwrite glibc-2.35-r0.apk
RUN apk fix --force-overwrite alpine-baselayout-data
RUN apk add --no-cache protoc grpc
ENV PROTOBUF_PROTOC=/usr/bin/protoc GRPC_PROTOC_PLUGIN=/usr/bin/grpc_csharp_plugin

# build here