CI: Modernize environment settings in Dockerfile

.docker/ci/Dockerfile

@@ -5,7 +5,7 @@ ARG ROS_DISTRO=noetic
 FROM ros:${ROS_DISTRO}-ros-base
 LABEL org.opencontainers.image.authors="Robert Haschke <[email protected]>"
 
-ENV TERM xterm
+ENV TERM=xterm
 
 # Setup (temporary) ROS workspace
 WORKDIR /root/ws_moveit
@@ -47,4 +47,4 @@ RUN \
     git config --global --add safe.directory "*"
 
 # Continous Integration Setting
-ENV IN_DOCKER 1
+ENV IN_DOCKER=1

.docker/source/Dockerfile

@@ -7,12 +7,12 @@ ARG IMAGE=noetic
 FROM moveit/moveit:${IMAGE}-ci-testing
 LABEL org.opencontainers.image.authors="Robert Haschke <[email protected]>"
 
-ENV PYTHONIOENCODING UTF-8
+ENV PYTHONIOENCODING=UTF-8
 # Export ROS_UNDERLAY for downstream docker containers
-ENV ROS_UNDERLAY /root/ws_moveit/install
+ENV ROS_UNDERLAY=/root/ws_moveit/install
 # Environment variable used in instructions on moveit.ros.org website for running clang-tidy
-ENV CATKIN_WS $(realpath $ROS_UNDERLAY/..)
-WORKDIR $ROS_UNDERLAY/..
+ENV CATKIN_WS=$ROS_UNDERLAY/..
+WORKDIR $CATKIN_WS
 
 # Copy MoveIt sources from docker context
 COPY . src/moveit