[bug1-repro] Supervisor port drain race

build.yaml

@@ -2,4 +2,5 @@ version: 1
 platform: python
 platformVersion: "3.14"
 run:
-  port: 8080
+  port: 8080
+  startCommand: "bash /output/flaky-startup.sh"

flaky-startup.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+set +e
+TAG="${EMBR_DEPLOYMENT_ID:-unknown}"
+echo "[healthy-startup ${TAG}] starting at $(date -u)"
+echo "[healthy-startup ${TAG}] PID=$$, PPID=$PPID"
+echo "[healthy-startup ${TAG}] ports in use BEFORE bind:"
+ss -ltnp 2>&1 | grep -E ':8080|LISTEN' | head -10
+echo "[healthy-startup ${TAG}] my parent process tree:"
+ps -ef --forest 2>&1 | head -30
+
+python -c "
+import socket, sys, time, os
+print(f'[healthy-startup {os.environ.get(\"EMBR_DEPLOYMENT_ID\",\"?\")}] attempting bind on :8080', flush=True)
+attempts = 0
+while attempts < 30:
+    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    try:
+        s.bind(('0.0.0.0', 8080))
+        s.listen(8)
+        print(f'[healthy-startup {os.environ.get(\"EMBR_DEPLOYMENT_ID\",\"?\")}] BOUND :8080 successfully after {attempts} attempts', flush=True)
+        break
+    except OSError as e:
+        attempts += 1
+        print(f'[healthy-startup {os.environ.get(\"EMBR_DEPLOYMENT_ID\",\"?\")}] BIND FAILED attempt {attempts}: {e}', flush=True)
+        s.close()
+        time.sleep(1)
+else:
+    print(f'[healthy-startup {os.environ.get(\"EMBR_DEPLOYMENT_ID\",\"?\")}] GAVE UP after 30 attempts', flush=True)
+    sys.exit(98)
+print(f'[healthy-startup {os.environ.get(\"EMBR_DEPLOYMENT_ID\",\"?\")}] serving forever now', flush=True)
+# minimal HTTP responder
+from http.server import HTTPServer, BaseHTTPRequestHandler
+class H(BaseHTTPRequestHandler):
+    def do_GET(self):
+        self.send_response(200); self.end_headers(); self.wfile.write(b'ok')
+    def log_message(self, *a): pass
+HTTPServer.allow_reuse_address = True
+HTTPServer(('0.0.0.0', 8080), H, bind_and_activate=False).serve_forever()
+" || true
+sleep 60