bind leaves a unix socket 0755 and connecting needs write, so the
gateway's nginx -- a different user -- would be locked out.
0666 is what hive-c0re already does for the per-agent sockets, and it
rests on the same argument: the containing directory is the access
control, not the socket mode. This directory holds one socket and is
bind-mounted into exactly one container.
That is also the sharper reason the socket does not live beside the host
admin socket. With a 0666 socket, a directory that carries more than it
should is not untidiness, it is the vulnerability.
First half of the swarm-controller slice: the crate, its workspace entry
and its daemonBins entry, so the systemd unit that follows has a binary
to point at.
It serves one health endpoint and owns no state. That is the whole
intent -- this makes the unit real (service user, runtime and state
directories, socket, nginx reachability) so the swarm-level surfaces
that follow have somewhere to land. Inventing those surfaces now would
bake in a shape nobody has agreed to.
The socket gets its own runtime directory rather than sharing
hive-c0re's. nginx reaches a unix upstream by having the socket's
directory bind-mounted into the gateway container, so co-locating this
socket with the host admin socket would hand the gateway that socket
too.
