Hopefully final initial fixes.

build_ros/Dockerfile

@@ -4,8 +4,8 @@ RUN apt-get update && apt-get install -y ros-galactic-ros-ign-gazebo
 RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y xserver-xorg-video-all libgl1-mesa-glx libgl1-mesa-dri libglvnd0 libgl1 libglx0 libegl1 libxext6 libx11-6
 RUN apt-get update && apt-get install -y libvulkan1 mesa-vulkan-drivers vulkan-utils mesa-utils
 
-ARG GID=1000
-ARG UID=1000
+ARG G_ID=1000
+ARG U_ID=1000
 
-RUN groupadd -f -g $GID ros
-RUN useradd -u $UID -g $GID -m ros
+RUN groupadd -f -g ${G_ID} ros
+RUN useradd -u ${U_ID} -g ${G_ID} -m ros