test: diagnose proxy startup failures

scripts/verifyProxy.py

@@ -10,6 +10,7 @@ import shutil
 import socket
 import ssl
 import subprocess
+import sys
 import tempfile
 import time
 
@@ -194,6 +195,7 @@ def main() -> None:
         try:
             backend_port = wait_for_native(backend, 120)
             write_nginx_config(directory / "nginx.conf", backend_port, edge_port)
+            print(f"proxy backend=127.0.0.1:{backend_port} edge=127.0.0.1:{edge_port}", flush=True)
             nginx = subprocess.Popen(
                 [
                     "docker", "run", "--rm", "--pull=missing", "--name", nginx_name,
@@ -218,7 +220,18 @@ def main() -> None:
             else:
                 raise RuntimeError("Nginx did not start listening")
 
-            wait_for_proxy(edge_port, 30)
+            try:
+                wait_for_proxy(edge_port, 30)
+            except Exception as error:
+                nginx_logs = subprocess.run(
+                    ["docker", "logs", nginx_name], capture_output=True, text=True, check=False
+                ).stdout[-2000:]
+                backend_logs = subprocess.run(
+                    ["docker", "logs", backend_name], capture_output=True, text=True, check=False
+                ).stdout[-2000:]
+                raise RuntimeError(
+                    f"{error}; nginx logs={nginx_logs!r}; backend logs={backend_logs!r}"
+                ) from error
             verify_keep_alive(edge_port)
             verify_timeout(edge_port)
             print("PASS Nginx TLS proxy, Keep-Alive and upstream timeout", flush=True)