Core: Alpine Linux Docker error when running .NET 2.1 - Error relocating /app/app-name/libcoreclr.so: gCurrentThreadInfo: symbol not found

[PSUPing]

Issue Title

Alpine Linux Docker error when running .NET Core 2.1 - Error relocating /app/app-name/libcoreclr.so: gCurrentThreadInfo: symbol not found

General

I created a Dockerfile to build and run a .NET Core 2.1 project using the new Alpine Linux images. When trying to run I get the following error:

Failed to load X?j?U, error: Error relocating /app/reactive-dotnet/libcoreclr.so: gCurrentThreadInfo: symbol not found
Failed to bind to CoreCLR at '/app/reactive-dotnet/libcoreclr.so'

Below is my csproj file

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp2.1</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.App" />
    <PackageReference Include="System.Reactive" Version="3.1.1" />
    <PackageReference Include="Npgsql" Version="3.2.7" />
    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="2.0.2" />
    <PackageReference Include="Newtonsoft.Json" Version="11.0.2" />
  </ItemGroup>

  <ItemGroup>
    <Folder Include="Model\" />
    <Folder Include="Controllers\" />
    <Folder Include="k8s\" />
    <Folder Include="k8s\postgres\" />
    <Folder Include="k8s\service\" />
    <Folder Include="commands\" />
    <Folder Include="database\" />
  </ItemGroup>
</Project>

Below is the Dockerfile I'm using to build and run the app:

FROM microsoft/dotnet:2.1-sdk-alpine AS build
WORKDIR /app/app-name

COPY *.csproj .
RUN dotnet restore

COPY . .
RUN dotnet publish -c Release -r linux-x64 -o out

# This builds the actual container that would run in k8s
FROM microsoft/dotnet:2.1-runtime-alpine AS runtime

RUN apk update && \
    apk upgrade --available && \
    apk add --update --no-cache libc6-compat

WORKDIR /app/app-name
COPY --from=build /app/app-name/out ./

# Add a user so that the container does not run as root
RUN adduser -G root appuser -D && \
    chgrp -R 0 /app && \
    chmod -R g+rwx /app

# Run this as the appuser
USER appuser

EXPOSE 8080

CMD [ "dotnet", "app-name.dll" ]

I dug around a little bit and have been trying do install various packages to overcome this. So far, I have tried to add:

• libcurl
• libgcc
• krb5-libs
• icu-libs
• lttng-ust-dev
• libssl1.0
• libstdc++
• libunwind
• libuuid
• zlib

Also, I tried removing the USER appuser line in the event that this was related to a permissions issue.

After some digging, I'm assuming this has to do with needing a threading library of some sort. A few of the packages above having threading libraries as dependencies, but did not fix the issue. If I'm missing a package, no problem to install, just curious on how to get this running. Thanks!

[Petermarcu]

Here is my first guess. You are publishing the application as self-contained but trying to launch it on a shared framework. What happens if your final command is just to launch the executable itself and not try to launch it through the dotnet shared host?

[PSUPing]

I looked through the build settings in VS and have a compile target of "Executable" and checked the "Do not reference mscorlib.dll". When doing dotnet publish in my Dockerfile i'm purposely avoiding the --self-contained flag. The app is an ASP.NET application (microservice). However, this error seemed to be with the dotnet CLR rather than something having to do with ASP.NET which is why I posted the issue in this project.

For fun, I just tried building and running as a self contained app. I changed from 2.1-runtime-alpine to 2.1-runtime-deps-alpine. I got the same error.

[Petermarcu]

-r on publish turns self-contained on by default. You can say --self-contained=false to turn it off. In your last scenario, how did you launch the application? Still trying to call dotnet app-name.dll?

[PSUPing]

I didn't realize that about -r. I've tried a couple different variants now.

Using the following two publish commands: dotnet publish -c Release -r linux-x64 --self-contained=false -o out or dotnet publish -c Release -o out I get the following error when running dotnet app-name.dll:

It was not possible to find any compatible framework version
The specified framework 'Microsoft.AspNetCore.App', version '2.1.0' was not found.
  - Check application dependencies and target a framework version installed at:
      /usr/share/dotnet/
  - Installing .NET Core prerequisites might help resolve this problem:
      http://go.microsoft.com/fwlink/?LinkID=798306&clcid=0x409
  - The .NET Core framework and SDK can be installed from:
      https://aka.ms/dotnet-download

I tried changing the publish command to dotnet publish -c Release -r linux-x64 -o out. I also changed the FROM line in my Dockerfile above to be FROM microsoft/dotnet:2.1-runtime-deps-alpine AS runtime. If I follow correctly, self-contained apps are meant for the deps image. I then ran ./app-name When I did that, I get same error as originally posted.

I'm almost wondering if there's something with one of the libraries that I'm importing that's causing this to go haywire. I started this out a few weeks ago on the .NET Core 2.0 framework running on an Ubuntu image. That ran without any issue. I was trying to move it to 2.1 because there were official Alpine images now. Just trying to think of different things that may be causing issues.

[Petermarcu]

Yeah, it would be good to narrow down the variable that changed. I forgot that Alpine is a different flavor of Linux so when you publish you need linux-musl-x64 for the runtime identifier. I'm not sure if that's going to fix this though.

[PSUPing]

Just hit me when I posted the last comment I need to use the aspnetcore image. Closing as this was not a real thing. Thanks for talking through though. Appreciate the help!

[nicojs]

Thanks @Petermarcu ! You're remark about linux-musl-x64 saved my skin! I kept getting this error: No such file or directory. As in:

$ docker run -it --entrypoint /bin/bash alpinetest
bash-4.4# ./AlpineTest
bash: ./AlpineTest: No such file or directory

For anyone else facing this issue: build for linux-musl-x64 instead of linux-x64

[sjbeskur]

So close I can almost taste it.... now I keep getting the following error:

Failed to load `��ȐU, error: Error loading shared library ld-linux-x86-64.so.2: No such file or directory (needed by /src/libhostpolicy.so)
An error occurred while loading required library libhostpolicy.so from [/src/]

[CodeSwimBikeRunner]

@sjbeskur apk add libc6-compat && apk add libunwind-dev

[CodeSwimBikeRunner]

@nicojs I'm getting "error : Project is targeting runtime 'linux-musl-x64' but did not resolve any runtime-specific packages. This runtime may not be supported by the target framework."

when I try to do that.

[nicojs]

@ChristopherLClark
I think the linux-musl-x64 target is added since dotnet core 2.1. You might need to upgrade. Anyway, I'm not actively working on a dotnet core project right now, so cannot validate or test anything. Best of luck to you.

[Petermarcu]

That's right, you need to be on at least 2.1