rticonnextdds-docker-crosscompile

This repository provides configuration files to generate Docker images for the cross-compilation of RTI Connext DDS applications.

Setup

Running Docker containers from a foreign architecture requires Qemu to be available on the system.

You can usually install Qemu via your distro's package manager, e.g. on Ubuntu:

sudo apt-get install -y qemu

Once Qemu is installed, you must enable hooks for it in the Docker daemon. This can be achieved using container hypriot/qemu-register:

docker run --rm --privileged hypriot/qemu-register

Image Use

The repository contains the following images:

Image	Host Architecture	Supported RTI Connext DDS Targets
rticonnextdds-builder-rpi3	armv7	armv7Linuxgcc7.3.0

Images can be built using the docker build command, e.g.:

cd rticonnextdds-docker-crosscompile/
docker build -t rticonnextdds-builder-rpi3 \
             -f images/builder-rpi3 \
             .

All images expect an RTI Connext DDS installation to be mounted via volume /rti/ndds. The target architecture can be specified via environment variable CONNEXTDDS_ARCH (passed via -e CONNEXTDDS_ARCH=<arch>), or a default value for the image will be used.

You can use the --rm option to automatically delete the container after completion, e.g.:

# Mount the current directory to build binaries for Raspberry Pi 3
docker run --rm -ti \
           -v ${NDDSHOME}:/rti/ndds \
           -v $(pwd):/work \
           rticonnextdds-builder-rpi3

Please be aware that compilation in the emulated environments will be extremely slow (a few orders of magnitude slower than native builds).

By default, the containers run commands as root, and generated files will have root-level permissions in the host. If you want files to be generated with the correct permissions you should use variables USER_ID and GROUP_ID to specify the user and group IDs to use inside the container.

For example, to match the current shell user and group (assumed to have the same name as the user):

docker run --rm -ti \
           -v ${NDDSHOME}:/rti/ndds \
           -v $(pwd):/work \
           -e USER_ID=$(id -u $(whoami)) \
           -e GROUP_ID=$(getent group $(whoami) | cut -d: -f3) \
           rticonnextdds-builder-rpi3

This will spawn a shell for user dsuser, member of group rti, with home directory set to /rti. If you prefer to use different user, group, and/or home directory, you can specify custom values via variables HOST_USER, HOST_GROUP, and HOME_DIR respectively.

rticonnextdds-builder-rpi3

This image is based on balenalib/raspberrypi3-debian:build. It provides an armv7 build environment running Raspbian Buster that can be used to build applications for Raspberry Pi 3.

The entry point script supports the specification of custom behavior via the following environment variables:

Variable	Description
ENVRC	Custom environment script that will be sourced on start up.
INIT	Custom initialization script that will be run on start up (after ENVRC).

The entry point script will copy a modified version of FindRTIConnextDDS.cmake into the mounted NDDSHOME, replacing the stock version with one modified to support armv7l and aarch64 architectures. The original file will be renamed and restored when the container exists.

The image also supports building connextdds-py by mounting volume /rti/connextdds-py with the contents of the connextdds-py git repository.

If connextdds-py is mounted, the container will temporarily modify connextdds-py's dependencies, by downgrading CMake from version 3.18 to version 3.14. The original configuration will be restored on exit.

The need for this change stems from a problem with stock builds of CMake between versions 3.15 and 3.18 that prevents them from working under emulated arm architectures. The only solution is to rebuild CMake with -D_FILE_OFFSET_BITS=64, so a version earlier than 3.15 is used instead to same time.

Usage Examples

Build connextdds-py for Raspberry Pi

On a system with RTI Connext DDS host x64Linux, and target armv7Linuxgcc7.3.0:

# Load RTI Connext DDS in environment
source /path/to/rti_connext_dds.6.0.1/resource/scripts/rtisetenv_armv7Linuxgcc7.3.0.bash

# Clone connextdds-py
git clone --recurse-submodules https://github.com/rticommunity/connextdds-py.git

# Start an ephemeral container to build connextdds-py for Raspberry Pi
docker run --rm -ti \
             -v ${NDDSHOME}:/rti/ndds \
             -v connextdds-py:/rti/connextdds-py \
             rticonnextdds-builder-rpi3

# Inside the container, enter connextdds-py/, configure the project, and
# build a wheel. This will likely take several hours. You can increase
# the number of parallel jobs by passing -j<n> to configure.py, keeping
# in mind that the compilation is memory-heavy and you might run out of memory
# if too many jobs are spawned concurrently.
cd /rti/connextdds-py
python3 configure.py ${CONNEXTDDS_ARCH}
pip3 wheel .