An agent container cannot dial the store's loopback listener: the bridge
to-loopback DROP rule is there precisely to stop that, and the store
authenticates every reader by client certificate, so the usual answer —
a gateway vhost — is the one shape that cannot work. A terminating proxy
strips the certificate and bao sees nginx as the client for every hive.
nginx's stream module does not terminate. `ssl_preread` reads the SNI off
the ClientHello and splices the rest of the connection through byte for
byte, so bao completes the handshake itself and authenticates the client
it actually has. That is the no-vhost rule kept, not bent.
The listener binds the bridge IP rather than every address, because bao
already holds `127.0.0.1:<port>` in the same netns and a wildcard bind
there is EADDRINUSE — nginx would fail to start, taking the gateway with
it. Nothing moves as a result: the name already resolves two ways, so a
host-side reader still goes straight to loopback and an agent goes
through the passthrough, both on one `BAO_ADDR`.
Renders only inside the store's own `deploy.bao.enable` region; a host
that runs no store grows no listener and opens no port.
Per-agent certificates and per-agent policy are separate work.
Refs #4386
ef2dfbfb31