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Discovery daemon

A REP service maintaining the registry of active topics. Publishers register on startup; subscribers look up the endpoint and connect directly.

Start

cortex-discovery

python -m cortex.discovery.daemon
/etc/systemd/system/cortex-discovery.service
[Unit]
Description=Cortex discovery daemon
After=network.target

[Service]
Type=simple
ExecStart=/usr/bin/env cortex-discovery
Restart=on-failure
RuntimeDirectory=cortex

[Install]
WantedBy=multi-user.target

Flags

Flag Default Description
--address ipc:///tmp/cortex/discovery.sock ZMQ endpoint to bind
--log-level INFO DEBUG / INFO / WARNING / ERROR

Lifecycle

stateDiagram-v2
    [*] --> Starting: bind REP socket
    Starting --> Running: socket ready
    Running --> Running: handle REGISTER / LOOKUP / LIST / UNREGISTER
    Running --> Stopping: SIGINT or SHUTDOWN command
    Stopping --> [*]: close socket, unlink ipc file

Troubleshooting

"Address already in use"
Another daemon or a stale socket file is holding the path. rm /tmp/cortex/discovery.sock and restart.
Subscribers time out looking up topics
Daemon not running, or the publisher failed to register. Run with --log-level DEBUG and watch for REGISTER / LOOKUP lines.
Daemon crash leaves stale entries
Entries are only removed on explicit UNREGISTER. A crashed publisher's topic stays in the registry pointing at a dead socket. Restarting the daemon clears all state.