[BUG] Gmod.NET is not working on Ubuntu 18.04 and older

[GlebChili]

Bug description

Garry's Mod Dedicated Server is not able to load Gmod.NET on Ubuntu 18.04 (newer versions work just fine).

Error message:

[ERROR] lua/autorun/start.lua:1: Couldn't load module library!

  1. require - [C]:-1

   2. unknown - lua/autorun/start.lua:1

Can be reproduced with the following Dockerfile:

FROM ubuntu:18.04
WORKDIR /steam
RUN apt-get update
RUN apt-get install -y lib32gcc1
RUN apt-get install -y curl
RUN curl -sqL "https://steamcdn-a.akamaihd.net/client/installer/steamcmd_linux.tar.gz" | tar zxvf -
RUN ./steamcmd.sh +login anonymous +force_install_dir /gmod "+app_update 4020 -beta x86-64 validate" +quit
WORKDIR /gmod/garrysmod/lua/bin
RUN curl -sqL "https://github.com/GmodNET/GmodDotNet/releases/download/0.7.1/gmod-dot-net-linux.0.7.1.tar.gz" | tar zxvf -
COPY start.lua /gmod/garrysmod/lua/autorun
RUN apt-get install -y libc6 libgcc1 libgssapi-krb5-2 libicu60 libssl1.1 libstdc++6 zlib1g
WORKDIR /gmod

ENTRYPOINT ./srcds_run_x64 -game garrysmod -systemtest -condebug +sv_hibernate_think 1

Posible cause

Since we are building C++ code of the Gmod.NET on Ubuntu 20.04, it is likely that we are implicitly linking to something (like newer libc version) which is not available on Ubuntu 18.04.

[SupinePandora43]

Can we update some library or link to library without version in name?

[GlebChili]

The problem is indeed an older version of libc and libstdc++. Here is an Ubuntu 18.04 dockerfile with a fix:

FROM ubuntu:18.04
WORKDIR /steam
RUN apt-get update
RUN apt-get install -y lib32gcc1
RUN apt-get install -y curl
RUN curl -sqL "https://steamcdn-a.akamaihd.net/client/installer/steamcmd_linux.tar.gz" | tar zxvf -
RUN ./steamcmd.sh +login anonymous +force_install_dir /gmod "+app_update 4020 -beta x86-64 validate" +quit
WORKDIR /gmod/garrysmod/lua/bin
RUN curl -sqL "https://github.com/GmodNET/GmodDotNet/releases/download/0.7.1/gmod-dot-net-linux.0.7.1.tar.gz" | tar zxvf -
COPY start.lua /gmod/garrysmod/lua/autorun
RUN apt-get install -y libc6 libgcc1 libgssapi-krb5-2 libicu60 libssl1.1 libstdc++6 zlib1g
RUN apt-get install -y software-properties-common
RUN add-apt-repository ppa:ubuntu-toolchain-r/test
RUN apt-get update
RUN apt-get install -y gcc-9 g++-9
WORKDIR /gmod

ENTRYPOINT ./srcds_run_x64 -game garrysmod -systemtest -condebug +sv_hibernate_think 1

TLDR if we install a gcc version 9 from experimental channel on Ubuntu 18.04, it brings newer libc and libstdc++ versions to system, and Gmod.NET works just fine.

Since we are using C++ 17 features in our bootstrapping module, we can't downgrade our build pipeline to Ubuntu 18.04 and GCC 7.

We need to create a docs article which will state that Linux distribution should be equipped with GCC 9 and newer (like Ubuntu 20.04) and if upgrade of the OS is not available, install newer version of GCC manually.

[WilliamVenner]

Hello guys, this is quite a common issue with Gmod modules. For my modules I build using a manylinux2014 Docker container which uses the ancient CentOS 7, and works even on the shittiest of Russian hosts.

Here is the github actions yml, hopefully it will help you

https://github.com/WilliamVenner/gmsv_workshop/blob/master/.github/workflows/build.yml