Saturday, March 2, 2024

An up to date information to Docker and ROS 2


2 years in the past, I wrote A Information to Docker and ROS, which is one in every of my most continuously considered posts — doubtless as a result of it’s a tough subject and folks have been in search of solutions. Since then, I’ve had the possibility to make use of Docker extra in my work and have picked up some new tips. This was lengthy overdue, however I’ve lastly collected my up to date learnings on this submit.

Lately, I encountered an article titled ROS Docker; 6 the reason why they aren’t a great match, and I largely agree with it. Nevertheless, the fact is that it’s nonetheless fairly tough to make sure a reproducible ROS setting for individuals who haven’t spent years preventing the ROS studying curve and are adept at debugging dependency and/or construct errors… so Docker continues to be very a lot a crutch that we fall again on to get working demos (and generally merchandise!) out the door.

If the article above hasn’t utterly discouraged you from embarking on this Docker journey, please take pleasure in studying.

Revisiting Our Dockerfile with ROS 2

Now that ROS 1 is on its remaining model and approaching finish of life in 2025, I assumed it might be acceptable to rehash the TurtleBot3 instance repo from the earlier submit utilizing ROS 2.

Many of the large adjustments on this improve must do with ROS 2, together with shopper libraries, launch recordsdata, and configuring DDS. The examples themselves have been up to date to make use of the most recent instruments for habits timber: BehaviorTree.CPP 4 / Groot 2 for C++ and py_trees / py_trees_ros_viewer for Python. For extra data on the instance and/or habits timber, consult with my Introduction to Habits Bushes submit.

From a Docker standpoint, there aren’t too many variations. Our container structure will now be as follows:

Layers of our TurtleBot3 instance Docker picture.

We’ll begin by making our Dockerfile, which defines the contents of our picture. Our preliminary base layer inherits from one of many public ROS photos, osrf/ros:humble-desktop, and units up the dependencies from our instance repository into an underlay workspace. These are outlined utilizing a vcstool repos file.

Discover that we’ve arrange the argument, ARG ROS_DISTRO=humble, so it may be modified for different distributions of ROS 2 (Iron, Rolling, and so forth.). Slightly than creating a number of Dockerfiles for various configurations, it’s best to attempt utilizing construct arguments like these as a lot as doable with out being “overly intelligent” in a approach that impacts readability.

ARG ROS_DISTRO=humble

########################################
# Base Picture for TurtleBot3 Simulation #
########################################
FROM osrf/ros:${ROS_DISTRO}-desktop as base
ENV ROS_DISTRO=${ROS_DISTRO}
SHELL [“/bin/bash”, “-c”]

# Create Colcon workspace with exterior dependencies
RUN mkdir -p /turtlebot3_ws/src
WORKDIR /turtlebot3_ws/src
COPY dependencies.repos .
RUN vcs import < dependencies.repos

# Construct the bottom Colcon workspace, putting in dependencies first.
WORKDIR /turtlebot3_ws
RUN supply /choose/ros/${ROS_DISTRO}/setup.bash
&& apt-get replace -y
&& rosdep set up –from-paths src –ignore-src –rosdistro ${ROS_DISTRO} -y
&& colcon construct –symlink-install
ENV TURTLEBOT3_MODEL=waffle_pi

To construct your picture with a selected argument — let’s say you wish to use ROS 2 Rolling as an alternative — you might do the next… supplied that every one your references to ${ROS_DISTRO} even have one thing that appropriately resolves to the rolling distribution.

docker construct -f docker/Dockerfile
--build-arg="ROS_DISTRO=rolling"
--target base -t turtlebot3_behavior:base .

I personally have had many points in ROS 2 Humble and later with the default DDS vendor (FastDDS), so I like to change my default implementation to Cyclone DDS by putting in it and setting an setting variable to make sure it’s all the time used.

# Use Cyclone DDS as middleware
RUN apt-get replace && apt-get set up -y --no-install-recommends
ros-${ROS_DISTRO}-rmw-cyclonedds-cpp
ENV RMW_IMPLEMENTATION=rmw_cyclonedds_cpp

Now, we’ll create our overlay layer. Right here, we’ll copy over the instance supply code, set up any lacking dependencies with rosdep set up, and arrange an entrypoint to run each time a container is launched.

###########################################
# Overlay Picture for TurtleBot3 Simulation #
###########################################
FROM base AS overlay

# Create an overlay Colcon workspace
RUN mkdir -p /overlay_ws/src
WORKDIR /overlay_ws
COPY ./tb3_autonomy/ ./src/tb3_autonomy/
COPY ./tb3_worlds/ ./src/tb3_worlds/
RUN supply /turtlebot3_ws/set up/setup.bash
&& rosdep set up –from-paths src –ignore-src –rosdistro ${ROS_DISTRO} -y
&& colcon construct –symlink-install

# Arrange the entrypoint
COPY ./docker/entrypoint.sh /
ENTRYPOINT [ “/entrypoint.sh” ]

The entrypoint outlined above is a Bash script that sources ROS 2 and any workspaces which are constructed, and units up setting variables essential to run our TurtleBot3 examples. You need to use entrypoints to do every other sorts of setup you would possibly discover helpful to your software.

#!/bin/bash
# Fundamental entrypoint for ROS / Colcon Docker containers

# Supply ROS 2
supply /choose/ros/${ROS_DISTRO}/setup.bash

# Supply the bottom workspace, if constructed
if [ -f /turtlebot3_ws/install/setup.bash ]
then
supply /turtlebot3_ws/set up/setup.bash
export TURTLEBOT3_MODEL=waffle_pi
export GAZEBO_MODEL_PATH=$GAZEBO_MODEL_PATH:$(ros2 pkg prefix turtlebot3_gazebo)/share/turtlebot3_gazebo/fashions
fi

# Supply the overlay workspace, if constructed
if [ -f /overlay_ws/install/setup.bash ]
then
supply /overlay_ws/set up/setup.bash
export GAZEBO_MODEL_PATH=$GAZEBO_MODEL_PATH:$(ros2 pkg prefix tb3_worlds)/share/tb3_worlds/fashions
fi

# Execute the command handed into this entrypoint
exec “$@”

At this level, it’s best to be capable to construct the complete Dockerfile:

docker construct
-f docker/Dockerfile --target overlay
-t turtlebot3_behavior:overlay .

Then, we will begin one in every of our instance launch recordsdata with the correct settings with this mouthful of a command. Most of those setting variables and volumes are wanted to have graphics and ROS 2 networking functioning correctly from inside our container.

docker run -it --net=host --ipc=host --privileged
--env="DISPLAY"
--env="QT_X11_NO_MITSHM=1"
--volume="/tmp/.X11-unix:/tmp/.X11-unix:rw"
--volume="${XAUTHORITY}:/root/.Xauthority"
turtlebot3_behavior:overlay
bash -c "ros2 launch tb3_worlds tb3_demo_world.launch.py"

Our TurtleBot3 instance simulation with RViz (left) and Gazebo traditional (proper).

Introducing Docker Compose

From the previous couple of snippets, we will see how the docker construct and docker run instructions can get actually lengthy and unwieldy as we add extra choices. You’ll be able to wrap this in a number of abstractions, together with scripting languages and Makefiles… however Docker has already solved this drawback via Docker Compose.

Briefly, Docker Compose means that you can create a YAML file that captures all of the configuration wanted to arrange constructing photos and working containers.

Docker Compose additionally differentiates itself from the “plain” Docker command in its capacity to orchestrate providers. This entails constructing a number of photos or targets inside the similar picture(s) and launching a number of applications on the similar time that comprise a complete software. It additionally enables you to prolong current providers to attenuate copy-pasting of the identical settings in a number of locations, outline variables, and extra.

The tip objective is that we have now brief instructions to handle our examples:

  • docker compose construct will construct what we want
  • docker compose up will launch what we want

Docker Compose permits us to extra simply construct and run our containerized examples.

The default title of this magical YAML file is docker-compose.yaml. For our instance, the docker-compose.yaml file seems to be as follows:

model: "3.9"
providers:
# Base picture containing dependencies.
base:
picture: turtlebot3_behavior:base
construct:
context: .
dockerfile: docker/Dockerfile
args:
ROS_DISTRO: humble
goal: base
# Interactive shell
stdin_open: true
tty: true
# Networking and IPC for ROS 2
network_mode: host
ipc: host
# Wanted to show graphical purposes
privileged: true
setting:
# Wanted to outline a TurtleBot3 mannequin sort
- TURTLEBOT3_MODEL=${TURTLEBOT3_MODEL:-waffle_pi}
# Permits graphical applications within the container.
- DISPLAY=${DISPLAY}
- QT_X11_NO_MITSHM=1
- NVIDIA_DRIVER_CAPABILITIES=all
volumes:
# Permits graphical applications within the container.
- /tmp/.X11-unix:/tmp/.X11-unix:rw
- ${XAUTHORITY:-$HOME/.Xauthority}:/root/.Xauthority

# Overlay picture containing the instance supply code.
overlay:
extends: base
picture: turtlebot3_behavior:overlay
construct:
context: .
dockerfile: docker/Dockerfile
goal: overlay

# Demo world
demo-world:
extends: overlay
command: ros2 launch tb3_worlds tb3_demo_world.launch.py

# Habits demo utilizing Python and py_trees
demo-behavior-py:
extends: overlay
command: >
ros2 launch tb3_autonomy tb3_demo_behavior_py.launch.py
tree_type:=${BT_TYPE:?}
enable_vision:=${ENABLE_VISION:?}
target_color:=${TARGET_COLOR:?}

# Habits demo utilizing C++ and BehaviorTree.CPP
demo-behavior-cpp:
extends: overlay
command: >
ros2 launch tb3_autonomy tb3_demo_behavior_cpp.launch.py
tree_type:=${BT_TYPE:?}
enable_vision:=${ENABLE_VISION:?}
target_color:=${TARGET_COLOR:?}

As you possibly can see from the Docker Compose file above, you possibly can specify variables utilizing the acquainted $ operator in Unix based mostly techniques. These variables will by default be learn from both your host setting or via an setting file (often referred to as .env). Our instance.env file seems to be like this:

# TurtleBot3 mannequin
TURTLEBOT3_MODEL=waffle_pi

# Habits tree sort: May be naive or queue.
BT_TYPE=queue

# Set to true to make use of imaginative and prescient, else false to solely do navigation behaviors.
ENABLE_VISION=true

# Goal shade for imaginative and prescient: May be pink, inexperienced, or blue.
TARGET_COLOR=blue

At this level, you possibly can construct every thing:

# By default, picks up a `docker-compose.yaml` and `.env` file.
docker compose construct

# You can too explicitly specify the recordsdata
docker compose –file docker-compose.yaml –env-file .env construct

Then, you possibly can run the providers you care about:

# Convey up the simulation
docker compose up demo-world

# After the simulation has began,
# launch one in every of these in a separate Terminal
docker compose up demo-behavior-py
docker compose up demo-behavior-cpp

The total TurtleBot3 demo working with py_trees because the Habits Tree.

Establishing Developer Containers

Our instance thus far works nice if we wish to bundle up working examples to different customers. Nevertheless, if you wish to develop the instance code inside this setting, you will have to beat the next obstacles:

  • Each time you modify your code, you will have to rebuild the Docker picture. This makes it extraordinarily inefficient to get suggestions on whether or not your adjustments are working as meant. That is already an on the spot deal-breaker.
  • You’ll be able to clear up the above by utilizing bind mounts to sync up the code in your host machine with that within the container. This will get us heading in the right direction, however you’ll discover that any recordsdata generated contained in the container and mounted on the host can be owned by root as default. You may get round this by whipping out the sudo and chown hammer, nevertheless it’s not mandatory.
  • All of the instruments you could use for improvement, together with debuggers, are doubtless lacking contained in the container… until you put in them within the Dockerfile, which might bloat the scale of your distribution picture.

Fortunately, there’s a idea of a developer container (or dev container). To place it merely, it is a separate container that permits you to really do your improvement in the identical Docker setting you’ll use to deploy your software.

There are various methods of implementing dev containers. For our instance, we’ll modify the Dockerfile so as to add a brand new dev goal that extends our current overlay goal.

Dev containers permit us to develop inside a container from our host system with minimal overhead.

This dev container will do the next:

  • Set up further packages that we might discover useful for improvement, equivalent to debuggers, textual content editors, and graphical developer instruments. Critically, these is not going to be a part of the overlay layer that we’ll ship to finish customers.
  • Create a brand new person that has the identical person and group identifiers because the person that constructed the container on the host. This can make it such that every one recordsdata generated inside the container (in folders we care about) have the identical possession settings as if we had created the file on our host. By “folders we care about”, we’re referring to the ROS workspace that accommodates the supply code.
  • Put our entrypoint script within the person’s Bash profile (~/.bashrc file). This lets us supply our ROS setting not simply at container startup, however each time we connect a brand new interactive shell whereas our dev container stays up.

#####################
# Improvement Picture #
#####################
FROM overlay as dev

# Dev container arguments
ARG USERNAME=devuser
ARG UID=1000
ARG GID=${UID}

# Set up additional instruments for improvement
RUN apt-get replace && apt-get set up -y –no-install-recommends
gdb gdbserver nano

# Create new person and residential listing
RUN groupadd –gid $GID $USERNAME
&& useradd –uid ${GID} –gid ${UID} –create-home ${USERNAME}
&& echo ${USERNAME} ALL=(root) NOPASSWD:ALL > /and so forth/sudoers.d/${USERNAME}
&& chmod 0440 /and so forth/sudoers.d/${USERNAME}
&& mkdir -p /house/${USERNAME}
&& chown -R ${UID}:${GID} /house/${USERNAME}

# Set the possession of the overlay workspace to the brand new person
RUN chown -R ${UID}:${GID} /overlay_ws/

# Set the person and supply entrypoint within the person’s .bashrc file
USER ${USERNAME}
RUN echo “supply /entrypoint.sh” >> /house/${USERNAME}/.bashrc

You’ll be able to then add a brand new dev service to the docker-compose.yaml file. Discover that we’re including the supply code as volumes to mount, however we’re additionally mapping the folders generated by colcon construct to a .colcon folder on our host file system. This makes it such that generated construct artifacts persist between stopping our dev container and bringing it again up, in any other case we’d must do a clear rebuild each time.

dev:
extends: overlay
picture: turtlebot3_behavior:dev
construct:
context: .
dockerfile: docker/Dockerfile
goal: dev
args:
- UID=${UID:-1000}
- GID=${UID:-1000}
- USERNAME=${USERNAME:-devuser}
volumes:
# Mount the supply code
- ./tb3_autonomy:/overlay_ws/src/tb3_autonomy:rw
- ./tb3_worlds:/overlay_ws/src/tb3_worlds:rw
# Mount colcon construct artifacts for quicker rebuilds
- ./.colcon/construct/:/overlay_ws/construct/:rw
- ./.colcon/set up/:/overlay_ws/set up/:rw
- ./.colcon/log/:/overlay_ws/log/:rw
person: ${USERNAME:-devuser}
command: sleep infinity

At this level you are able to do:

# Begin the dev container
docker compose up dev

# Connect an interactive shell in a separate Terminal
# NOTE: You are able to do this a number of occasions!
docker compose exec -it dev bash

As a result of we have now mounted the supply code, you can also make modifications in your host and rebuild contained in the dev container… or you should use helpful instruments just like the Visible Studio Code Containers extension to immediately develop contained in the container. As much as you.

For instance, when you’re contained in the container you possibly can construct the workspace with:

colcon construct

On account of our quantity mounts, you’ll see that the contents of the .colcon/construct, .colcon/set up, and .colcon/log folders in your host have been populated. Which means that in the event you shut down the dev container and produce up a brand new occasion, these recordsdata will live on and can velocity up rebuilds utilizing colcon construct.

Additionally, as a result of we have now gone via the difficulty of creating a person, you’ll see that these recordsdata are usually not owned by root, so you possibly can delete them in the event you’d like to scrub out the construct artifacts. It’s best to do that with out making the brand new person and also you’ll run into some annoying permissions roadblocks.

$ ls -al .colcon
whole 20
drwxrwxr-x 5 sebastian sebastian 4096 Jul 9 10:15 .
drwxrwxr-x 10 sebastian sebastian 4096 Jul 9 10:15 ..
drwxrwxr-x 4 sebastian sebastian 4096 Jul 9 11:29 construct
drwxrwxr-x 4 sebastian sebastian 4096 Jul 9 11:29 set up
drwxrwxr-x 5 sebastian sebastian 4096 Jul 9 11:31 log

The idea of dev containers is so widespread at this level that an ordinary has emerged at containers.dev. I additionally wish to level out another nice assets together with Allison Thackston’s weblog, Griswald Brooks’ GitHub repo, and the official VSCode dev containers tutorial.

Conclusion

On this submit, you have got seen how Docker and Docker Compose may help you create reproducible ROS 2 environments. This consists of the flexibility to configure variables at construct and run time, in addition to creating dev containers that will help you develop your code in these environments earlier than distributing it to others.

We’ve solely scratched the floor on this submit, so be sure you poke round on the assets linked all through, check out the instance repository, and usually keep interested by what else you are able to do with Docker to make your life (and your customers’ lives) simpler.

As all the time, please be at liberty to succeed in out with questions and suggestions. Docker is a extremely configurable software, so I’m genuinely interested by how this works for you or whether or not you have got approached issues otherwise in your work. I’d study one thing new!


Sebastian Castro
is a Senior Robotics Engineer at PickNik.

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