Adds ROS2 Humble to Dockerfile (#443)

# Description

This adds a ROS2 Humble installation to the Dockerfile. It also adds
several relevant environment variables.

## Type of change

- New feature (non-breaking change which adds functionality)

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./orbit.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] I have run all the tests with `./orbit.sh --test` and they pass
- [ ] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

---------
Signed-off-by: Hunter Hansen <50837800+hhansen-bdai@users.noreply.github.com>
Co-authored-by: James Smith <142246516+jsmith-bdai@users.noreply.github.com>

docker/.env → docker/.env.base

+###
+# General settings
+###
+
 # Accept the NVIDIA Omniverse EULA by default
 ACCEPT_EULA=Y
 # NVIDIA Isaac Sim version to use (e.g. 2023.1.1, 2023.1.0-hotfix.1)

docker/.env.ros2

+###
+# ROS2 specific settings
+###
+# Set the version of the ROS2 apt package to install (ros-base, desktop, desktop-full)
+ROS2_APT_PACKAGE=ros-base
+# Se t ROS2 middleware implementation to use (e.g. rmw_fastrtps_cpp, rmw_cyclonedds_cpp)
+RMW_IMPLEMENTATION=rmw_fastrtps_cpp
+# Path to fastdds.xml file to use (only needed when using fastdds)
+FASTRTPS_DEFAULT_PROFILES_FILE=${DOCKER_USER_HOME}/.ros/fastdds.xml
+# Path to cyclonedds.xml file to use (only needed when using cyclonedds)
+CYCLONEDDS_URI=${DOCKER_USER_HOME}/.ros/cyclonedds.xml

docker/.ros/cyclonedds.xml

+ <?xml version="1.0" encoding="UTF-8" ?>
+<CycloneDDS xmlns="https://cdds.io/config" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="https://cdds.io/config https://raw.githubusercontent.com/eclipse-cyclonedds/cyclonedds/master/etc/cyclonedds.xsd">
+  <Domain id="any">
+    <General>
+      <Interfaces>
+        <NetworkInterface autodetermine="true"/>
+      </Interfaces>
+      <AllowMulticast>true</AllowMulticast>
+    </General>
+    <Discovery>
+      <ParticipantIndex>auto</ParticipantIndex>
+      <MaxAutoParticipantIndex>120</MaxAutoParticipantIndex>
+    </Discovery>
+  </Domain>
+</CycloneDDS>

docker/.ros/fastdds.xml

+<?xml version="1.0" encoding="UTF-8" ?>
+
+<license>Copyright (c) 2022, NVIDIA CORPORATION.  All rights reserved.
+NVIDIA CORPORATION and its licensors retain all intellectual property
+and proprietary rights in and to this software, related documentation
+and any modifications thereto.  Any use, reproduction, disclosure or
+distribution of this software and related documentation without an express
+license agreement from NVIDIA CORPORATION is strictly prohibited.</license>
+
+
+<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles" >
+    <transport_descriptors>
+        <transport_descriptor>
+            <transport_id>UdpTransport</transport_id>
+            <type>UDPv4</type>
+        </transport_descriptor>
+    </transport_descriptors>
+
+    <participant profile_name="udp_transport_profile" is_default_profile="true">
+        <rtps>
+            <userTransports>
+                <transport_id>UdpTransport</transport_id>
+            </userTransports>
+            <useBuiltinTransports>false</useBuiltinTransports>
+        </rtps>
+    </participant>
+</profiles>

docker/Dockerfile → docker/Dockerfile.base

@@ -8,7 +8,7 @@
 
 # Base image
 ARG ISAACSIM_VERSION
-FROM nvcr.io/nvidia/isaac-sim:${ISAACSIM_VERSION}
+FROM nvcr.io/nvidia/isaac-sim:${ISAACSIM_VERSION} AS base
 
 # Set default RUN shell to bash
 SHELL ["/bin/bash", "-c"]
@@ -20,16 +20,18 @@ LABEL description="Dockerfile for building and running the Orbit framework insid
 # Arguments
 # Path to Isaac Sim root folder
 ARG ISAACSIM_PATH
-# Path to the Docker User Home
+# Home dir of docker user, typically '/root'
 ARG DOCKER_USER_HOME
 
 # Set environment variables
 ENV LANG=C.UTF-8
 ENV DEBIAN_FRONTEND=noninteractive
+# Path to orbit directory
 ENV ORBIT_PATH=/workspace/orbit
 
 # Install dependencies and remove cache
-RUN apt-get update && apt-get install -y --no-install-recommends \
+RUN --mount=type=cache,target=/var/cache/apt \
+    apt-get update && apt-get install -y --no-install-recommends \
     build-essential \
     cmake \
     git \
@@ -66,7 +68,7 @@ RUN touch /bin/nvidia-smi && \
 
 # installing Orbit dependencies
 # use pip caching to avoid reinstalling large packages
-RUN --mount=type=cache,target=/${DOCKER_USER_HOME}/.cache/pip \
+RUN --mount=type=cache,target=${DOCKER_USER_HOME}/.cache/pip \
     ${ORBIT_PATH}/orbit.sh --install --extra
 
 # aliasing orbit.sh and python for convenience

docker/Dockerfile.ros2

+# Everything past this stage is to install
+# ROS2 Humble
+FROM orbit-base AS ros2
+
+# Which ROS2 apt package to install
+ARG ROS2_APT_PACKAGE
+# Home of the docker user, generally /root
+ARG DOCKER_USER_HOME
+
+# ROS2 Humble Apt installations
+RUN --mount=type=cache,target=/var/cache/apt \
+    apt-get update && apt-get install -y --no-install-recommends \
+    curl \
+    # Install ROS2 Humble \
+    software-properties-common && \
+    add-apt-repository universe && \
+    curl -sSL https://raw.githubusercontent.com/ros/rosdistro/master/ros.key -o /usr/share/keyrings/ros-archive-keyring.gpg && \
+    echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/ros-archive-keyring.gpg] http://packages.ros.org/ros2/ubuntu $(. /etc/os-release && echo jammy) main" | tee /etc/apt/sources.list.d/ros2.list > /dev/null && \
+    apt-get update && apt-get install -y --no-install-recommends \
+    ros-humble-${ROS2_APT_PACKAGE} \
+    ros-humble-vision-msgs \
+    # Install both FastRTPS and CycloneDDS
+    ros-humble-rmw-cyclonedds-cpp \
+    ros-humble-rmw-fastrtps-cpp \
+    # This includes various dev tools including colcon
+    ros-dev-tools && \
+    apt -y autoremove && apt clean autoclean && \
+    rm -rf /var/lib/apt/lists/* && \
+    # Add sourcing of setup.bash to .bashrc
+    echo "source /opt/ros/humble/setup.bash" >> ${HOME}/.bashrc
+
+# Copy the RMW specifications for ROS2
+# https://docs.omniverse.nvidia.com/isaacsim/latest/installation/install_ros.html#enabling-the-ros-bridge-extension
+COPY docker/.ros/ ${DOCKER_USER_HOME}/.ros/

docker/container.sh

@@ -84,7 +84,24 @@ case $mode in
     start)
         echo "[INFO] Building the docker image and starting the container in the background..."
         pushd ${SCRIPT_DIR} > /dev/null 2>&1
-        docker compose --file docker-compose.yaml up --detach --build --remove-orphans
+        # The second argument is interpreted as the profile to use.
+        # We will select the base profile by default.
+        # This will also determine the .env file that is loaded
+        if [ -z "$2" ]; then
+            add_profiles="--profile base"
+            add_envs="--env-file .env.base"
+        else
+            profile="$2"
+            add_profiles="--profile $profile"
+            # We have to load multiple .env files here in order to combine
+            # them for the args from base required for extensions, (i.e. DOCKER_USER_HOME)
+            add_envs="--env-file .env.base --env-file .env.$profile"
+        fi
+        # We have to build the base image as a separate step,
+        # in case we are building a profile which depends
+        # upon
+        docker compose --file docker-compose.yaml --env-file .env.base build orbit-base
+        docker compose --file docker-compose.yaml $add_profiles $add_envs up --detach --build --remove-orphans
         popd > /dev/null 2>&1
         ;;
     enter)
@@ -124,7 +141,17 @@ case $mode in
     stop)
         echo "[INFO] Stopping the launched docker container..."
         pushd ${SCRIPT_DIR} > /dev/null 2>&1
-        docker compose --file docker-compose.yaml down
+        if [ -z "$2" ]; then
+            add_profiles="--profile base"
+            add_envs="--env-file .env.base"
+        else
+            profile="$2"
+            add_profiles="--profile $profile"
+            # We have to load multiple .env files here in order to combine
+            # them for the args from base required for ROS2, (i.e. DOCKER_USER_HOME)
+            add_envs="--env-file .env.base --env-file .env.$profile"
+        fi
+        docker compose --file docker-compose.yaml $add_profiles $add_envs down
         popd > /dev/null 2>&1
         ;;
     push)
@@ -133,10 +160,10 @@ case $mode in
         fi
         # Check if Docker version is greater than 25
         check_docker_version
-        # Check if .env file exists
-        if [ -f $SCRIPT_DIR/.env ]; then
+        # Check if .env.base file exists
+        if [ -f $SCRIPT_DIR/.env.base ]; then
             # source env file to get cluster login and path information
-            source $SCRIPT_DIR/.env
+            source $SCRIPT_DIR/.env.base
             # clear old exports
             sudo rm -r -f /$SCRIPT_DIR/exports
             mkdir -p /$SCRIPT_DIR/exports
@@ -147,21 +174,21 @@ case $mode in
             tar -cvf /$SCRIPT_DIR/exports/orbit.tar orbit.sif
             scp /$SCRIPT_DIR/exports/orbit.tar $CLUSTER_LOGIN:$CLUSTER_SIF_PATH/orbit.tar
         else
-            echo "[Error]: ".env" file not found."
+            echo "[Error]: ".env.base" file not found."
         fi
         ;;
     job)
         # Check if .env file exists
-        if [ -f $SCRIPT_DIR/.env ]; then
+        if [ -f $SCRIPT_DIR/.env.base ]; then
             # Sync orbit code
             echo "[INFO] Syncing orbit code..."
-            source $SCRIPT_DIR/.env
+            source $SCRIPT_DIR/.env.base
             rsync -rh  --exclude="*.git*" --filter=':- .dockerignore'  /$SCRIPT_DIR/.. $CLUSTER_LOGIN:$CLUSTER_ORBIT_DIR
             # execute job script
             echo "[INFO] Executing job script..."
             ssh $CLUSTER_LOGIN "cd $CLUSTER_ORBIT_DIR && sbatch $CLUSTER_ORBIT_DIR/docker/cluster/submit_job.sh" "$CLUSTER_ORBIT_DIR" "${@:2}"
         else
-            echo "[Error]: ".env" file not found."
+            echo "[Error]: ".env.base" file not found."
         fi
         ;;
     *)

docker/docker-compose.yaml

+version: "3.4"
+# Here we set the parts that would
+# be re-used between services to an
+# extension field
+# https://docs.docker.com/compose/compose-file/compose-file-v3/#extension-fields
+x-default-orbit-volumes:
+  &default-orbit-volumes
+    # These volumes follow from this page
+    # https://docs.omniverse.nvidia.com/app_isaacsim/app_isaacsim/install_faq.html#save-isaac-sim-configs-on-local-disk
+    - type: volume
+      source: isaac-cache-kit
+      target: ${DOCKER_ISAACSIM_PATH}/kit/cache
+    - type: volume
+      source: isaac-cache-ov
+      target: ${DOCKER_USER_HOME}/.cache/ov
+    - type: volume
+      source: isaac-cache-pip
+      target: ${DOCKER_USER_HOME}/.cache/pip
+    - type: volume
+      source: isaac-cache-gl
+      target: ${DOCKER_USER_HOME}/.cache/nvidia/GLCache
+    - type: volume
+      source: isaac-cache-compute
+      target: ${DOCKER_USER_HOME}/.nv/ComputeCache
+    - type: volume
+      source: isaac-logs
+      target: ${DOCKER_USER_HOME}/.nvidia-omniverse/logs
+    - type: volume
+      source: isaac-carb-logs
+      target: ${DOCKER_ISAACSIM_PATH}/kit/logs/Kit/Isaac-Sim
+    - type: volume
+      source: isaac-data
+      target: ${DOCKER_USER_HOME}/.local/share/ov/data
+    - type: volume
+      source: isaac-docs
+      target: ${DOCKER_USER_HOME}/Documents
+      # These volumes allow X11 Forwarding
+      # We currently comment these out because they can
+      # cause bugs and warnings for people uninterested in
+      # X11 Forwarding from within the docker. We keep them
+      # as comments as a convenience for those seeking X11
+      # forwarding until a scripted solution is developed
+    # - type: bind
+    #   source: /tmp/.X11-unix
+    #   target: /tmp/.X11-unix
+    # - type: bind
+    #   source: ${HOME}/.Xauthority
+    #   target: ${DOCKER_USER_HOME}/.Xauthority
+      # This overlay allows changes on the local files to
+      # be reflected within the container immediately
+    - type: bind
+      source: ../source
+      target: /workspace/orbit/source
+    - type: bind
+      source: ../docs
+      target: /workspace/orbit/docs
+      # The effect of these volumes is twofold:
+      # 1. Prevent root-owned files from flooding the _build and logs dir
+      #    on the host machine
+      # 2. Preserve the artifacts in persistent volumes for later copying
+      #    to the host machine
+    - type: volume
+      source: orbit-docs
+      target: /workspace/orbit/docs/_build
+    - type: volume
+      source: orbit-logs
+      target: /workspace/orbit/logs
+    - type: volume
+      source: orbit-data
+      target: /workspace/orbit/data_storage
+
+x-default-orbit-deploy:
+  &default-orbit-deploy
+    resources:
+      reservations:
+        devices:
+          - driver: nvidia
+            count: all
+            capabilities: [ gpu ]
+
 services:
-  # This service is used to build the Docker image
-  # The docker image is built from the root directory
-  orbit:
+  # This service is the base Orbit image
+  orbit-base:
+    profiles: ["base"]
+    env_file: .env.base
     build:
       context: ../
-      dockerfile: docker/Dockerfile
+      dockerfile: docker/Dockerfile.base
       args:
         - ISAACSIM_VERSION=${ISAACSIM_VERSION}
         - ISAACSIM_PATH=${DOCKER_ISAACSIM_PATH}
         - DOCKER_USER_HOME=${DOCKER_USER_HOME}
-    image: orbit
+    image: orbit-base
     container_name: orbit
-    env_file:
-      - .env
+    environment:
       # We set DOCKER_ISAACSIM_PATH and then forward it to ISAACSIM_PATH within
       # the container to avoid collision with pre-existing ISAACSIM_PATH env vars
-      # that could come from installing Orbit on the local machine, causing build errors
-    environment:
+      # that could come from installing Orbit on the local machine, causing build errors.
+      # We can't just define this in the .env file because shell envars take precedence
+      # https://docs.docker.com/compose/environment-variables/envvars-precedence/
       - ISAACSIM_PATH=${DOCKER_ISAACSIM_PATH}
       # This should also be enabled for X11 forwarding
       # - DISPLAY=${DISPLAY}
-    volumes:
-      # These volumes follow from this page
-      # https://docs.omniverse.nvidia.com/app_isaacsim/app_isaacsim/install_faq.html#save-isaac-sim-configs-on-local-disk
-      - type: volume
-        source: isaac-cache-kit
-        target: ${DOCKER_ISAACSIM_PATH}/kit/cache
-      - type: volume
-        source: isaac-cache-ov
-        target: ${DOCKER_USER_HOME}/.cache/ov
-      - type: volume
-        source: isaac-cache-pip
-        target: ${DOCKER_USER_HOME}/.cache/pip
-      - type: volume
-        source: isaac-cache-gl
-        target: ${DOCKER_USER_HOME}/.cache/nvidia/GLCache
-      - type: volume
-        source: isaac-cache-compute
-        target: ${DOCKER_USER_HOME}/.nv/ComputeCache
-      - type: volume
-        source: isaac-logs
-        target: ${DOCKER_USER_HOME}/.nvidia-omniverse/logs
-      - type: volume
-        source: isaac-carb-logs
-        target: ${DOCKER_ISAACSIM_PATH}/kit/logs/Kit/Isaac-Sim
-      - type: volume
-        source: isaac-data
-        target: ${DOCKER_USER_HOME}/.local/share/ov/data
-      - type: volume
-        source: isaac-docs
-        target: ${DOCKER_USER_HOME}/Documents
-        # These volumes allow X11 Forwarding
-        # We currently comment these out because they can
-        # cause bugs and warnings for people uninterested in
-        # X11 Forwarding from within the docker. We keep them
-        # as comments as a convenience for those seeking X11
-        # forwarding until a scripted solution is developed
-      # - type: bind
-      #   source: /tmp/.X11-unix
-      #   target: /tmp/.X11-unix
-      # - type: bind
-      #   source: ${HOME}/.Xauthority
-      #   target: ${DOCKER_USER_HOME}/.Xauthority
-        # This overlay allows changes on the local files to
-        # be reflected within the container immediately
-      - type: bind
-        source: ../source
-        target: /workspace/orbit/source
-      - type: bind
-        source: ../docs
-        target: /workspace/orbit/docs
-        # The effect of these volumes is twofold:
-        # 1. Prevent root-owned files from flooding the _build and logs dir
-        #    on the host machine
-        # 2. Preserve the artifacts in persistent volumes for later copying
-        #    to the host machine
-      - type: volume
-        source: orbit-docs
-        target: /workspace/orbit/docs/_build
-      - type: volume
-        source: orbit-logs
-        target: /workspace/orbit/logs
-      - type: volume
-        source: orbit-data
-        target: /workspace/orbit/data_storage
+    volumes: *default-orbit-volumes
+    network_mode: host
+    deploy: *default-orbit-deploy
+    # This is the entrypoint for the container
+    entrypoint: bash
+    stdin_open: true
+    tty: true
+
+  # This service adds a ROS2 Humble
+  # installation on top of the base image
+  orbit-ros2:
+    profiles: ["ros2"]
+    env_file:
+      - .env.base
+      - .env.ros2
+    build:
+      context: ../
+      dockerfile: docker/Dockerfile.ros2
+      args:
+          # ROS2_APT_PACKAGE will default to NONE. This is to
+          # avoid a warning message when building only the base profile
+          # with the .env.base file
+        - ROS2_APT_PACKAGE=${ROS2_APT_PACKAGE:-NONE}
+        - DOCKER_USER_HOME=${DOCKER_USER_HOME}
+    image: orbit-ros2
+    container_name: orbit
+    environment:
+      - ISAACSIM_PATH=${DOCKER_ISAACSIM_PATH}
+    volumes: *default-orbit-volumes
     network_mode: host
-    deploy:
-      resources:
-        reservations:
-          devices:
-            - driver: nvidia
-              count: all
-              capabilities: [ gpu ]
+    deploy: *default-orbit-deploy
     # This is the entrypoint for the container
     entrypoint: bash
     stdin_open: true

docs/source/deployment/docker.rst

@@ -66,13 +66,15 @@ Directory Organization
 ----------------------
 
 The root of the Orbit repository contains the ``docker`` directory that has various files and scripts
-needed to run Orbit inside a Docker container. These are summarized below:
+needed to run Orbit inside a Docker container. A subset of these are summarized below:
 
-* ``Dockerfile``: Defines orbit image by overlaying Orbit dependencies onto the Isaac Sim Docker image.
+* ``Dockerfile.base``: Defines the orbit image by overlaying Orbit dependencies onto the Isaac Sim Docker image.
+  ``Dockerfiles`` which end with something else, (i.e. ``Dockerfile.ros2``) build an `image_extension <#orbit-image-extensions>`_.
 * ``docker-compose.yaml``: Creates mounts to allow direct editing of Orbit code from the host machine that runs
-  the container along with X11 forwarding. It also creates several named volumes such as ``isaac-cache-kit`` to store frequently
-  re-used resources compiled by Isaac Sim, such as shaders, and to retain logs, data, and documents.
-* ``.env``: Stores environment variables required for the build process and the container itself.
+  the container along with X11 forwarding. It also creates several named volumes such as ``isaac-cache-kit`` to
+  store frequently re-used resources compiled by Isaac Sim, such as shaders, and to retain logs, data, and documents.
+* ``base.env``: Stores environment variables required for the ``base`` build process and the container itself. ``.env``
+  files which end with something else (i.e. ``.env.ros2``) define these for `image_extension <#orbit-image-extensions>`_.
 * ``container.sh``: A script that wraps the ``docker-compose`` command to build the image and run the container.
 
 Running the Container
@@ -94,9 +96,10 @@ Running the Container
 
 The script ``container.sh`` wraps around three basic ``docker-compose`` commands:
 
-1. ``start``: This builds the image and brings up the container in detached mode (i.e. in the background).
+1. ``start``: This builds the image and brings up the container in detached mode (i.e. in the background). It can accept an
+   `image_extension argument <#orbit-image-extensions>`_.
 2. ``enter``: This begins a new bash process in an existing orbit container, and which can be exited
-   without bringing down the container.
+   without bringing down the container.  It can accept an `image_extension argument <#orbit-image-extensions>`_.
 3. ``copy``: This copies the ``logs``, ``data_storage`` and ``docs/_build`` artifacts, from the ``orbit-logs``, ``orbit-data`` and ``orbit-docs``
    volumes respectively, to the ``docker/artifacts`` directory. These artifacts persist between docker
    container instances.
@@ -121,14 +124,7 @@ To copy files from the container to the host machine, you can use the following
 The script ``container.sh`` provides a wrapper around this command to copy the ``logs`` , ``data_storage`` and ``docs/_build``
 directories to the ``docker/artifacts`` directory. This is useful for copying the logs, data and documentation:
 
-.. code:: bash
-
-    # Copy the logs, data_storage and docs/_build directories to the docker/artifacts directory
-    ./docker/container.sh copy
-
-To stop the container, you can use the following command:
-
-.. code:: bash
+.. code::
 
     # stop the container
     ./docker/container.sh stop
@@ -163,7 +159,7 @@ These are summarized below:
 * ``isaac-data``: This volume is used to store data generated by Omniverse. (`/root/.local/share/ov/data` in container)
 * ``isaac-docs``: This volume is used to store documents generated by Omniverse. (`/root/Documents` in container)
 * ``orbit-docs``: This volume is used to store documentation of Orbit when built inside the container. (`/workspace/orbit/docs/_build` in container)
-* ``orbit-logs``: This volume is used to store logs generated by Orbit workflows when ran inside the container. (`/workspace/orbit/logs` in container)
+* ``orbit-logs``: This volume is used to store logs generated by Orbit workflows when run inside the container. (`/workspace/orbit/logs` in container)
 * ``orbit-data``: This volume is used to store whatever data users may want to preserve between container runs. (`/workspace/orbit/data_storage` in container)
 
 To view the contents of these volumes, you can use the following command:
@@ -176,6 +172,40 @@ To view the contents of these volumes, you can use the following command:
     docker volume inspect isaac-cache-kit
 
 
+
+Orbit Image Extensions
+----------------------
+
+The produced image depends upon the arguments passed to ``./container.sh start`` and ``./container.sh stop``. These
+commands accept an ``image_extension`` as an additional argument. If no argument is passed, then these
+commands default to ``base``. Currently, the only valid ``image_extension`` arguments are (``base``, ``ros2``).
+Only one ``image_extension`` can be passed at a time, and the produced container will be named ``orbit``.
+
+.. code:: bash
+
+    # start base by default
+    ./container.sh start
+    # stop base explicitly
+    ./container.sh stop base
+    # start ros2 container
+    ./container.sh start ros2
+    # stop ros2 container
+    ./container.sh stop ros2
+
+The passed ``image_extension`` argument will build the image defined in ``Dockerfile.${image_extension}``,
+with the corresponding `profile`_ in the ``docker-compose.yaml`` and the envars from ``.env.${image_extension}``
+in addition to the ``.env.base``, if any.
+
+ROS2 Image Extension
+~~~~~~~~~~~~~~~~~~~~
+
+In ``Dockerfile.ros2``, the container installs ROS2 Humble via an `apt package`_, and it is sourced in the ``.bashrc``.
+The exact version is specified by the variable ``ROS_APT_PACKAGE`` in the ``.env.ros2`` file,
+defaulting to ``ros-base``. Other relevant ROS2 variables are also specified in the ``.env.ros2`` file,
+including variables defining the `various middleware`_ options. The container defaults to ``FastRTPS``, but ``CylconeDDS``
+is also supported. Each of these middlewares can be `tuned`_ using their corresponding ``.xml`` files under ``docker/.ros``.
+
+
 Known Issues
 ------------
 
@@ -246,3 +276,7 @@ in docker-compose.yaml.
 .. _`NGC API key`: https://docs.nvidia.com/ngc/gpu-cloud/ngc-user-guide/index.html#generating-api-key
 .. _`several streaming clients`: https://docs.omniverse.nvidia.com/isaacsim/latest/installation/manual_livestream_clients.html
 .. _`known issue`: https://forums.developer.nvidia.com/t/unable-to-use-webrtc-when-i-run-runheadless-webrtc-sh-in-remote-headless-container/222916
+.. _`Docker compose profile`: https://docs.docker.com/compose/compose-file/15-profiles/
+.. _`apt package`: https://docs.ros.org/en/humble/Installation/Ubuntu-Install-Debians.html#install-ros-2-packages
+.. _`various middleware`: https://docs.ros.org/en/humble/How-To-Guides/Working-with-multiple-RMW-implementations.html
+.. _`tuned`: https://docs.ros.org/en/foxy/How-To-Guides/DDS-tuning.html