A hive that does not host authelia has no path to its own agent queue
client secret. The mint writes the plaintext to a host directory whose
other reader lives in a different container, so the host that mints is
the only place both trees are addressable — which is where this unit
runs.
Four pieces, in the order they depend on each other: the leaf
(glue-bao-tls.nix signs it, because the thing that owns a private key
owns issuing from it), the module declaring its own cert/key options,
the one-pairing glue file pointing them at that leaf, and the imports.
The unit is gated on holding a client identity, never on
deploy.bao.enable — that option is the co-location assumption itself,
and the publisher is the case that assumption excludes.
The secret is passed to bao as `value=@<path>`, never as an argv
element: bao is an external binary, so an argument is world-readable in
/proc for the life of the call.
Refs #3853
eaa52ef200