Upgrade coordinator to least-loaded routing (checks active torrent count per worker)

servers/legion/k8s/media/fornax-coordinator.yaml

@@ -12,19 +12,18 @@ data:
   coordinator.py: |
     #!/usr/bin/env python3
     """
-    Fornax coordinator — round-robin proxy for qBittorrent API.
-    - POST /api/v2/torrents/add  → round-robins across all backends
+    Fornax coordinator — least-loaded proxy for qBittorrent API.
+    - POST /api/v2/torrents/add  → routed to worker with fewest active torrents
     - Everything else            → proxied to primary backend (qbittorrent)
     Manages its own SID sessions to each backend so auth is transparent.
     """
-    import itertools, os, urllib.request, urllib.parse
+    import json, os, urllib.request, urllib.parse
     from http.server import HTTPServer, BaseHTTPRequestHandler
 
     BACKENDS = [b.strip() for b in os.environ.get("BACKENDS", "").split(",") if b.strip()]
     USER = os.environ.get("QBT_USER", "admin")
     PASS = os.environ.get("QBT_PASS", "adminadmin")
     PRIMARY = BACKENDS[0] if BACKENDS else ""
-    pool = itertools.cycle(BACKENDS)
     sids = {}
 
     def fetch_sid(backend):
@@ -44,9 +43,26 @@ data:
             sids[backend] = fetch_sid(backend)
         return sids.get(backend, "")
 
+    def active_count(backend):
+        """Return number of downloading torrents on this backend, or large int on error."""
+        try:
+            req = urllib.request.Request(
+                f"{backend}/api/v2/torrents/info?filter=downloading",
+                headers={"Cookie": f"SID={sid(backend)}"},
+            )
+            with urllib.request.urlopen(req, timeout=3) as r:
+                return len(json.loads(r.read()))
+        except Exception:
+            return 9999
+
+    def least_loaded():
+        counts = {b: active_count(b) for b in BACKENDS}
+        chosen = min(counts, key=counts.get)
+        print(f"  load: {counts} → routing to {chosen}")
+        return chosen
+
     def forward(backend, method, path, body, content_type):
-        cookie = f"SID={sid(backend)}"
-        headers = {"Cookie": cookie}
+        headers = {"Cookie": f"SID={sid(backend)}"}
         if content_type:
             headers["Content-Type"] = content_type
         req = urllib.request.Request(
@@ -57,8 +73,7 @@ data:
             with urllib.request.urlopen(req, timeout=30) as r:
                 return r.status, r.read(), list(r.getheaders())
         except urllib.error.HTTPError as e:
-            # SID expired — refresh once and retry
-            if e.code == 403:
+            if e.code == 403:  # SID expired — refresh once and retry
                 sids[backend] = fetch_sid(backend)
                 headers["Cookie"] = f"SID={sids[backend]}"
                 req2 = urllib.request.Request(
@@ -76,24 +91,19 @@ data:
 
     class Handler(BaseHTTPRequestHandler):
         def log_message(self, fmt, *args):
-            print(f"{self.command} {self.path} → {args[1] if len(args) > 1 else ''}")
+            print(f"{self.command} {self.path}")
 
         def _proxy(self, method):
             length = int(self.headers.get("Content-Length", 0))
             body = self.rfile.read(length) if length else None
             ct = self.headers.get("Content-Type", "")
 
-            if method == "POST" and "/api/v2/torrents/add" in self.path:
-                backend = next(pool)
-                print(f"  routing add → {backend}")
-            else:
-                backend = PRIMARY
+            backend = least_loaded() if (method == "POST" and "/api/v2/torrents/add" in self.path) else PRIMARY
 
             status, resp_body, resp_headers = forward(backend, method, self.path, body, ct)
             self.send_response(status)
-            skip = {"transfer-encoding", "connection"}
             for k, v in resp_headers:
-                if k.lower() not in skip:
+                if k.lower() not in {"transfer-encoding", "connection"}:
                     self.send_header(k, v)
             self.end_headers()
             self.wfile.write(resp_body)