[ADD] improve usability of docker container and docker instructions

docker/Dockerfile.noetic

@@ -44,18 +44,30 @@ RUN apt-get update && apt-get -y --no-install-recommends install \
     ros-noetic-vision-msgs \
     ros-noetic-visualization-msgs \
     ros-noetic-rviz \
+    # Optionall install RealSense2 package
+    ros-noetic-realsense2-camera \
     && apt-get -y autoremove \
     && apt-get clean
 
 # Install required Python components
 RUN python3 -m pip install -r /tmp/requirements.txt
 
-# Source ROS noetic
+# Copy and set up the ros_entrypoint.sh
+COPY ./docker/ros_entrypoint.sh /ros_entrypoint.sh
+RUN chmod +x /ros_entrypoint.sh
+
+# Make sure the catkin workspace is initialized
 RUN . /opt/ros/noetic/setup.sh && \
-    ./tmp/init_workspace.sh
+    /tmp/init_workspace.sh
+
+# Set the entrypoint to ros_entrypoint.sh
+ENTRYPOINT ["/ros_entrypoint.sh"]
+
+# Default command
+CMD ["bash"]
 
-# Set Display variables
+# Set Display variables for GUI applications
 ENV DISPLAY=:0
 ENV TERM=xterm
 # Some QT-Apps do not show controls without this
-ENV QT_X11_NO_MITSHM=1
+ENV QT_X11_NO_MITSHM=1

docker/ros_entrypoint.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+# Source ROS distribution and Catkin Workspace
+source /opt/ros/noetic/setup.bash
+source ${DEVEL}/setup.bash
+
+exec "$@"

docs/DOCKER.md

@@ -30,7 +30,11 @@ This will take several minutes and require connection to the internet. This comm
    - `name` specifies the name of the image. By default, it is `trackdlo`. Multiple containers can be created from the same image by changing this parameter.
    - `host dir` and `container dir` map a directory on the host machine to a location inside the container. This enables sharing code and data between the two systems. By default, the `run_docker.sh` bash script maps the directory containing trackdlo to `/root/tracking_ws/src/trackdlo` in the container.
 
-    Only the first call of this script with a given name will create a container. Subsequent executions will attach to the running container to enable running multiple terminal sessions in a single container.
+    Only the first call of this script with a given name will create a container. Subsequent executions will attach to the running container to enable running multiple terminal sessions in a single container. In subsequent calls, please check that ROS and the built catkin workspace are properly sourced.
+
+    ```
+    source /ros_entrypoint.sh
+    ```
 
    *Note:* Since the Docker container binds directly to the host's network, it will see `roscore` even if running outside the docker container.