Cannot find EGL device in a headless nvidia cudagl container

[AlbertYang0112]

Hi, thank you for your repo!

I'm trying to run MuJoCo which uses PyOpenGL as graphic backend in a headless docker container nvidia/cudagl:11.4.2-runtime-ubuntu20.04. I find with EGL in PyOpenGL, my GPU cannot be detected, i.e., eglQueryDevicesEXT returns a empty list.

However, my GPU is detectable with a simple code written with CPP (from here):

#include <EGL/eglext.h>


void assertEGLError(const std::string& msg) {
    EGLint error = eglGetError();

    if (error != EGL_SUCCESS) {
        std::stringstream s;
        s << "EGL error 0x" << std::hex << error << " at " << msg;
        throw std::runtime_error(s.str());
    }
}
int main(int argc, char *argv[])
{

    int deviceID = 0;  // TODO hardcode

    EGLDisplay eglDpy;
    EGLConfig config;
    EGLContext context;
    EGLint num_config;

    static const int MAX_DEVICES = 16;
    EGLDeviceEXT eglDevs[MAX_DEVICES];
    EGLint numDevices;

    PFNEGLQUERYDEVICESEXTPROC eglQueryDevicesEXT =
            (PFNEGLQUERYDEVICESEXTPROC)eglGetProcAddress("eglQueryDevicesEXT");

    eglQueryDevicesEXT(MAX_DEVICES, eglDevs, &numDevices);
    printf("Detected %d devices\n", numDevices);
    PFNEGLGETPLATFORMDISPLAYEXTPROC eglGetPlatformDisplayEXT =
            (PFNEGLGETPLATFORMDISPLAYEXTPROC)eglGetProcAddress("eglGetPlatformDisplayEXT");

    // Choose device by deviceID
    eglDpy = eglGetPlatformDisplayEXT(EGL_PLATFORM_DEVICE_EXT, eglDevs[deviceID], nullptr);

    assertEGLError("eglGetDisplay");

    return 0;
} 

Which prints Detected 3 devices. I looked into the dynamic library loaded by PyOpenGL but I find nothing unusual:

load <ctypes.LibraryLoader object at 0x7f4fb0a7b8e0> GLX 256
load <ctypes.LibraryLoader object at 0x7f4fb0a7b8e0> GLESv2 256
load <ctypes.LibraryLoader object at 0x7f4fb0a7b8e0> EGL 256
load <ctypes.LibraryLoader object at 0x7f4fb0a7b8e0> OpenGL 256  

Could you please help me with that? Thanks.