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#!/usr/bin/env python3
"""ODS mDNS announcer.
Publishes the device on the local network as `<ODS_DEVICE_NAME>.local`
(default `ods.local`) plus per-service `_http._tcp` records so any device
on the same LAN can find the dashboard and chat UI without knowing the IP.
When paired with ods-proxy on port 80, this makes the "open `ods.local`
from any phone" UX work: the device boots, joins WiFi, and starts announcing
itself within seconds.
Reads `ODS_DEVICE_NAME` and the service ports from `.env`. Re-publishes
when the file changes (poll-based, 30s cadence) so renaming the device or
changing a port doesn't require a service restart.
Linux-first: relies on `avahi-daemon` being installed and running (already
standard on Ubuntu / Debian / Fedora / Arch desktop installs). macOS has
built-in mDNS via mDNSResponder and announces hostname.local automatically;
this script is a no-op on Darwin (logs and exits 0). Windows mDNS support
varies — see BRANDING.md / docs/MDNS.md for follow-up.
Run via:
python3 /opt/ods/bin/ods-mdns.py
or via the ods-mdns.service systemd unit.
"""
from __future__ import annotations
import logging
import os
import platform
import re
import signal
import socket
import sys
import time
from pathlib import Path
# zeroconf import is deferred past the platform gate in main(). macOS has
# built-in Bonjour and Windows isn't covered yet — neither should hard-fail
# at start just because the package isn't installed.
IPVersion = None # type: ignore
ServiceInfo = None # type: ignore
Zeroconf = None # type: ignore
def _import_zeroconf_or_die() -> None:
"""Linux-only path. Imports zeroconf lazily so non-Linux platforms can
exit cleanly without the package installed."""
global IPVersion, ServiceInfo, Zeroconf
try:
from zeroconf import IPVersion as _IPVersion # noqa: PLC0415
from zeroconf import ServiceInfo as _ServiceInfo # noqa: PLC0415
from zeroconf import Zeroconf as _Zeroconf # noqa: PLC0415
except ImportError:
print(
"ERROR: `zeroconf` Python package not installed. "
"On Debian/Ubuntu: sudo apt install python3-zeroconf. "
"On Fedora: sudo dnf install python3-zeroconf. "
"On Arch: sudo pacman -S python-zeroconf.",
file=sys.stderr,
)
sys.exit(1)
IPVersion = _IPVersion
ServiceInfo = _ServiceInfo
Zeroconf = _Zeroconf
logging.basicConfig(
level=os.environ.get("ODS_MDNS_LOG_LEVEL", "INFO"),
format="%(asctime)s [ods-mdns] %(levelname)s %(message)s",
)
logger = logging.getLogger(__name__)
INSTALL_DIR = Path(os.environ.get("ODS_INSTALL_DIR", "/opt/ods"))
ENV_FILE = INSTALL_DIR / ".env"
def _safe_positive_int_env(key: str, default: int) -> int:
raw = os.environ.get(key, "")
if raw == "":
return default
try:
value = int(raw)
except (TypeError, ValueError):
logger.warning("Env %s=%r is not a valid integer; using default %d", key, raw, default)
return default
if value <= 0:
logger.warning("Env %s=%r is non-positive; using default %d", key, raw, default)
return default
return value
POLL_INTERVAL = _safe_positive_int_env("ODS_MDNS_POLL_INTERVAL", 30)
# Hostname-safe pattern matches ODS_DEVICE_NAME schema in .env.schema.json.
_HOSTNAME_RE = re.compile(r"^[a-zA-Z0-9]([a-zA-Z0-9-]{0,30}[a-zA-Z0-9])?$")
def _read_env() -> dict[str, str]:
"""Return current .env values, ignoring comments and blank lines."""
if not ENV_FILE.is_file():
return {}
env: dict[str, str] = {}
for line in ENV_FILE.read_text(encoding="utf-8").splitlines():
stripped = line.strip()
if not stripped or stripped.startswith("#") or "=" not in stripped:
continue
key, _, value = stripped.partition("=")
env[key.strip()] = value.strip().strip('"').strip("'")
return env
def _get_local_ip() -> str:
"""Best-effort local IPv4 address for the LAN-facing interface.
Opens a UDP socket to a non-routable address — the kernel picks the
interface it would use to reach the public internet, which is the same
interface we want to announce on. Never actually sends a packet.
"""
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
try:
s.connect(("8.8.8.8", 80))
ip: str = s.getsockname()[0]
except OSError:
ip = "127.0.0.1"
finally:
s.close()
return ip
def _safe_port(env: dict[str, str], key: str, default: int) -> int:
"""Parse a port from .env. Tolerant of blank/non-numeric values.
The .env file is intentionally user-editable, so a typo in WEBUI_PORT
must not crash the announcer (which would then restart on a systemd
loop, spamming logs). On bad input we log and fall back to the default;
the next refresh picks up the fix once the user corrects .env.
"""
raw = env.get(key, "")
if raw == "":
return default
try:
value = int(raw)
except (TypeError, ValueError):
logger.warning(
"Env %s=%r is not a valid integer; using default %d", key, raw, default,
)
return default
if value <= 0 or value > 65535:
logger.warning(
"Env %s=%r is outside the valid TCP/UDP port range; using default %d", key, raw, default,
)
return default
return value
def _normalized_bind_address(env: dict[str, str]) -> str:
return (env.get("BIND_ADDRESS") or "127.0.0.1").strip().lower()
def _direct_ports_lan_reachable(env: dict[str, str]) -> bool:
"""Direct host ports are only truthful when the services bind to the LAN.
The default ODS posture keeps service ports on 127.0.0.1 and exposes only
ods-proxy on the LAN. In that default, advertise the proxy hostnames but
do not publish direct-port SRV records that would point LAN clients at
unreachable endpoints.
"""
bind = _normalized_bind_address(env)
return bind not in {"", "127.0.0.1", "localhost", "::1"}
def _build_services(env: dict[str, str], device_name: str, ip: str) -> list[ServiceInfo]:
"""Build the ServiceInfo records to publish.
Two flavors of record:
1. Direct-port SRV records under `_http._tcp.local.` (the historical
shape — backward-compatible with MCP clients and service-discovery
tools). These point at the underlying service ports (3000, 3001,
3002) for clients that want to bypass the proxy.
2. Per-subdomain A records (`chat.<device>.local`, `auth.<device>.local`,
`dashboard.<device>.local`, `hermes.<device>.local`) all pointing at
the device's LAN IP on port 80 — the ods-proxy. The proxy
routes by Host header. The A record is a side effect of registering
a ServiceInfo whose `server` field is the hostname we want
resolvable.
Each service that isn't configured (port <= 0 or missing) is dropped
from publication. Subdomain records are always published as long as
ODS_DEVICE_NAME is valid — the proxy itself decides at routing
time whether the upstream is healthy.
"""
addresses = [socket.inet_aton(ip)]
proxy_port = _safe_port(env, "ODS_PROXY_PORT", 80)
infos: list[ServiceInfo] = []
# ----- Direct-port SRV records (back-compat for service discovery) ----
if _direct_ports_lan_reachable(env):
direct: list[tuple[str, int, str, dict[str, str]]] = [
# (suffix, port, label, extra_txt)
("dashboard", _safe_port(env, "DASHBOARD_REMOTE_PORT", 3011), "ODS Dashboard", {"path": "/"}),
("chat", _safe_port(env, "WEBUI_PORT", 3000), "ODS Chat", {"path": "/"}),
("dashboard-api", _safe_port(env, "DASHBOARD_API_PORT", 3002), "ODS API", {"path": "/health"}),
# Announce unconditionally when direct ports are LAN-reachable:
# the Hermes extension is opt-in via `ods enable hermes`, but
# the failure mode when disabled is the same as any optional
# service that is not running.
("hermes", _safe_port(env, "HERMES_PORT", 9119), "Hermes Agent", {"path": "/api/health"}),
]
for suffix, port, label, txt in direct:
infos.append(ServiceInfo(
type_="_http._tcp.local.",
name=f"{device_name}-{suffix}._http._tcp.local.",
addresses=addresses,
port=port,
properties={**txt, "label": label, "device": device_name, "kind": "direct"},
server=f"{device_name}.local.",
))
else:
logger.info("Skipping direct-port SRV records because BIND_ADDRESS is loopback-only")
# ----- Per-subdomain A records (proxy-routed) -------------------------
# Each entry registers a `<sub>.<device>.local.` A record (or bare
# `<device>.local.` for "root") by virtue of being the `server` of the
# ServiceInfo. Port is the proxy's listen port; the proxy routes by Host
# header to the right backend.
subdomain_routes = (
("root", "ODS Root Redirect (via proxy)"),
("chat", "ODS Chat (via proxy)"),
("dashboard", "ODS Dashboard (via proxy)"),
("auth", "ODS Auth (magic-link redemption)"),
("api", "ODS API (admin)"),
# hermes is announced unconditionally; the proxy 502s when the
# upstream container isn't running, which is the right failure
# mode for an optional extension.
("hermes", "Hermes Agent (via proxy)"),
# talk.<device>.local is the owner-card redemption target for the
# mobile portal added in #1319. magic_link.py's _talk_url() points
# phones at this hostname; ods-proxy's Caddy block routes it to
# the dashboard container's /talk route. Without an A record here
# the redirect lands the phone on an unresolvable host and the
# owner experience stalls on a white screen.
("talk", "ODS Talk (mobile owner portal)"),
)
for suffix, label in subdomain_routes:
server = f"{device_name}.local." if suffix == "root" else f"{suffix}.{device_name}.local."
infos.append(ServiceInfo(
type_="_http._tcp.local.",
name=f"{device_name}-proxy-{suffix}._http._tcp.local.",
addresses=addresses,
port=proxy_port,
properties={"path": "/", "label": label, "device": device_name, "kind": "proxy"},
server=server,
))
return infos
class Announcer:
"""Manages the lifecycle of mDNS service publications.
Holds onto the active Zeroconf handle and the currently-registered
services so a config change can re-register cleanly.
"""
def __init__(self) -> None:
self.zc: Zeroconf | None = None
self.registered: list[ServiceInfo] = []
self.last_signature: tuple[str, str, str, int, int, int, int, int] | None = None
def _config_signature(self, device_name: str, ip: str, env: dict[str, str]) -> tuple[str, str, str, int, int, int, int, int]:
"""Compact summary of what we'd publish — re-announce on change.
Includes ODS_PROXY_PORT so that flipping the proxy to a non-
standard port (rare, but supported) triggers re-announcement of
the per-subdomain SRV records.
"""
return (
device_name,
ip,
_normalized_bind_address(env),
_safe_port(env, "DASHBOARD_REMOTE_PORT", 3011),
_safe_port(env, "WEBUI_PORT", 3000),
_safe_port(env, "DASHBOARD_API_PORT", 3002),
_safe_port(env, "HERMES_PORT", 9119),
_safe_port(env, "ODS_PROXY_PORT", 80),
)
def refresh(self) -> None:
env = _read_env()
device_name = env.get("ODS_DEVICE_NAME", "ods") or "ods"
if not _HOSTNAME_RE.match(device_name):
logger.warning(
"ODS_DEVICE_NAME %r is not hostname-safe; falling back to 'ods'",
device_name,
)
device_name = "ods"
ip = _get_local_ip()
signature = self._config_signature(device_name, ip, env)
if signature == self.last_signature and self.zc is not None:
return
if self.zc is not None:
logger.info("Config changed — re-registering mDNS services")
self._teardown()
self.zc = Zeroconf(ip_version=IPVersion.V4Only)
services = _build_services(env, device_name, ip)
for info in services:
self.zc.register_service(info)
self.registered.append(info)
logger.info(
"Published %s -> %s:%d (server %s)",
info.name, ip, info.port, info.server,
)
self.last_signature = signature
def _teardown(self) -> None:
# The signature describes live registrations, not the last successful
# attempt. A failed rename followed by reverting .env must republish.
self.last_signature = None
if self.zc is None:
return
for info in self.registered:
try:
self.zc.unregister_service(info)
except (OSError, RuntimeError) as exc:
logger.warning("Failed to unregister %s: %s", info.name, exc)
self.zc.close()
self.zc = None
self.registered = []
def shutdown(self) -> None:
logger.info("Shutting down mDNS announcer")
self._teardown()
def main() -> int:
if platform.system() == "Darwin":
logger.info(
"Darwin host detected — macOS mDNSResponder already announces hostname.local; "
"this script is a no-op on macOS. Exiting cleanly."
)
return 0
if platform.system() == "Windows":
logger.info(
"Windows host detected — mDNS support varies; this script is not yet supported on Windows. "
"See docs for follow-up. Exiting cleanly."
)
return 0
# Linux path: zeroconf is required from here on. Imported lazily so the
# no-op exits above don't trip on a missing package.
_import_zeroconf_or_die()
if not ENV_FILE.is_file():
logger.error("Env file not found at %s — cannot determine device config.", ENV_FILE)
return 1
announcer = Announcer()
def _on_signal(signum: int, _frame: object) -> None:
logger.info("Received signal %d", signum)
announcer.shutdown()
sys.exit(0)
signal.signal(signal.SIGINT, _on_signal)
signal.signal(signal.SIGTERM, _on_signal)
logger.info("Starting ODS mDNS announcer (poll every %ds)", POLL_INTERVAL)
while True:
try:
announcer.refresh()
except (OSError, RuntimeError, ValueError) as exc:
# ValueError covers any int-conversion failures we missed above —
# the alternative is a crashloop that masks the real config bug.
logger.exception("Refresh failed: %s", exc)
time.sleep(POLL_INTERVAL)
if __name__ == "__main__":
sys.exit(main())