Bind GeoIP service to IPv6 for Railway private networking

Author: Rieranthony

apps/geoip/.env.default

@@ -1,5 +1,6 @@
 # GeoIP service
 GEOIP_DB_DIR=/data/geoip
+HOST=::
 PORT=8080
 
 # Local API -> GeoIP service

apps/geoip/README.md

@@ -29,6 +29,7 @@ MAXMIND_LICENSE_KEY=<secret>
 MAXMIND_EDITION_IDS=GeoLite2-City GeoLite2-ASN
 GEOIP_DB_DIR=/data/geoip
 GEOIP_UPDATE_INTERVAL_HOURS=24
+HOST=::
 PORT=8080
 ```
 
@@ -57,10 +58,12 @@ GEOIP_SERVICE_URL=http://localhost:8083
 
 Deploy this app as its own Railway service named `geoip`.
 
+The service binds to `::` by default so Railway private networking can reach it in both new dual-stack environments and older IPv6-only ones.
+
 The main API should use:
 
 ```env
-GEOIP_SERVICE_URL=http://geoip.railway.internal
+GEOIP_SERVICE_URL=http://geoip.railway.internal:8080
 ```
 
 Only the `geoip` service needs the MaxMind credentials.

apps/geoip/src/config.py

@@ -22,6 +22,7 @@ class Settings:
 	license_key: str
 	edition_ids: tuple[str, ...]
 	db_dir: Path
+	host: str
 	update_interval_hours: int
 	port: int
 
@@ -48,7 +49,7 @@ def from_env(cls) -> "Settings":
 			license_key=os.getenv("MAXMIND_LICENSE_KEY", "").strip(),
 			edition_ids=_split_edition_ids(os.getenv("MAXMIND_EDITION_IDS")),
 			db_dir=Path(os.getenv("GEOIP_DB_DIR", "/data/geoip")),
+			host=os.getenv("HOST", "::").strip() or "::",
 			update_interval_hours=int(os.getenv("GEOIP_UPDATE_INTERVAL_HOURS", "24")),
 			port=int(os.getenv("PORT", "8080")),
 		)
-

apps/geoip/src/main.py

@@ -70,4 +70,4 @@ async def lookup(payload: LookupRequest) -> LookupResponse:
 
 if __name__ == "__main__":
 	settings = Settings.from_env()
-	uvicorn.run("src.main:app", host="0.0.0.0", port=settings.port)
+	uvicorn.run("src.main:app", host=settings.host, port=settings.port)