By default, all make targets working with containers or container images will use podman if it is installed - and fall back to Docker if not.
You can force the usage of Docker with make CONTAINER_ENGINE=docker ....
By default, make build-services (and all make targets depending on it) will trigger up to 7 jobs in parallel to build the subcomponents.
You can change this behavior by overriding BUILD_SERVICES_OPTS and providing an alternative -j parameter for make, e.g.
make BUILD_SERVICES_OPTS="-j1" ...will limit number of parallel jobs to 1make BUILD_SERVICES_OPTS="-j" ...will not limit number of parallel jobs