ci(docker): require the full integration suite

scripts/docker_host_address.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+"""Print the Docker host address seen by a socket-shared Linux CI container."""
+
+from __future__ import annotations
+
+import socket
+import struct
+import sys
+from pathlib import Path
+
+
+def default_ipv4_gateway(route_table: str) -> str:
+    """Return the active default gateway from Linux ``/proc/net/route``."""
+
+    for line in route_table.splitlines()[1:]:
+        fields = line.split()
+        if len(fields) < 4 or fields[1] != "00000000":
+            continue
+        try:
+            gateway = int(fields[2], 16)
+            flags = int(fields[3], 16)
+        except ValueError:
+            continue
+        if flags & 0x2:  # RTF_GATEWAY
+            return socket.inet_ntoa(struct.pack("<I", gateway))
+    raise ValueError("no active IPv4 default gateway in /proc/net/route")
+
+
+def main() -> int:
+    try:
+        print(default_ipv4_gateway(Path("/proc/net/route").read_text(encoding="utf-8")))
+    except (OSError, ValueError) as exc:
+        print(f"docker-host-address: {exc}", file=sys.stderr)
+        return 1
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())