Hi @windy_hinger, when you compile OpenCV, you want to build it with -D WITH_GSTREAMER=ON option to enable GStreamer. You can check out the @mdegans OpenCV build script which enables GStreamer and CUDA/cuDNN.
Alternatively, you can install into your container the version of OpenCV that comes with JetPack (which already has GStreamer enabled) by adopting this example from this Dockerfile: