Building Open AD kit as a Yocto distribution

[esteve]

As part of the CI efforts and to streamline Open AD kit for production, @kasperornmeck proposed using Yocto as a way to build a custom Linux distribution.

For context, Yocto is not a distribution itself, but a set of tools for creating one tailored to one's specifics needs. In our case, it'd generate Open AD kit distributions with only the components we'd need or would want to distribute.

In order to accomplish this, Yocto uses BitBake as its build tool. BitBake is part of the OpenEmbedded, which uses "recipes" to build packages. Several attempts at maintaining BitBake recipes for ROS have been created, being meta-ros the most successful one.

meta-ros was originally created by BMW, and later on, LG joined the project.

The current implementation of meta-ros is automatically generated via a tool called Super Flore, which simplifies the maintenance heavily by querying the dependency graph of released packages for a given ROS distribution. Therefore, Super Flore can only work with packages that have been released into ROS

For Open AD kit, this means that we can use meta-ros to build ROS, however the BitBake recipes for Autoware.core/universe components will need to be either crafted manually or if we want to use Super Flore, the packages will need to be released into the ROS buildfarm.

[kaspermeck-arm]

@esteve

Using Yocto to build containers using meta-ros needs more investigation and is not our highest priority. As of now, we only use Yocto to build the custom Linux distro EWAOL, which is the host OS. So far it has been ported to e.g., AVA, RPi4, and other hardware.

My suggestion is that we use multi-stage builds (https://docs.docker.com/develop/develop-images/multistage-build/) to create container images which are based on Ubuntu. Each container image will have ROS nodes which relate a specific feature, e.g., localization.

Once we have implemented a multi-stage buildpipeline, we can swap out Ubuntu (in the FROM statement in the Dockerfile) with a custom Linux build.

What do you think about that?

[esteve]

@kasperornmeck yes, I know it's not a priority now, but I was asked by @mitsudome-r to summarize my findings about Yocto here