Update Dockerfile

Author: jwinarske

ubuntu-20-dev/Dockerfile

@@ -92,5 +92,5 @@ RUN set -ex \
   && tar xzf cmake-${CMAKE_VERSION}-Linux-x86_64.tar.gz -C /home/dev/cmake --strip-components=1 \
   && rm -rf cmake-${CMAKE_VERSION}*
 
-RUN echo 'export DOCKER_HOST=unix:///run/user/$user_id/podman/podman.sock' >> /home/$USER_NAME/.bashrc
+RUN echo 'export DOCKER_HOST=unix:///run/user/$RUNNER_USER_UID/podman/podman.sock' >> /home/$USER_NAME/.bashrc
 RUN echo 'export PATH=/home/dev/bin:/home/dev/cmake/bin:$PATH' >> /home/$USER_NAME/.bashrc