fix: make SSH inventory discovery more reliable on CI

Increase default SSH timeout, reduce scan concurrency, and add a second slower scan pass to avoid transient misses on busy runners. Also print discovered hostnames to improve failure diagnostics when node-name matching fails.

nixos/kubeadm/scripts/discover-inventory-from-ssh.py

@@ -80,8 +80,8 @@ def main() -> int:
     ssh_user = os.environ.get("KUBEADM_SSH_USER", "").strip() or "micqdf"
     users = [u for u in os.environ.get("SSH_USER_CANDIDATES", f"{ssh_user} root").split() if u]
     key_path = os.environ.get("SSH_KEY_PATH", os.path.expanduser("~/.ssh/id_ed25519"))
-    timeout_sec = int(os.environ.get("SSH_DISCOVERY_TIMEOUT_SEC", "3"))
-    max_workers = int(os.environ.get("SSH_DISCOVERY_WORKERS", "64"))
+    timeout_sec = int(os.environ.get("SSH_DISCOVERY_TIMEOUT_SEC", "6"))
+    max_workers = int(os.environ.get("SSH_DISCOVERY_WORKERS", "32"))
 
     prefix = derive_prefix(payload)
     start = int(os.environ.get("KUBEADM_SUBNET_START", "2"))
@@ -90,20 +90,33 @@ def main() -> int:
     scan_ips = [str(ipaddress.IPv4Address(f"{prefix}.{i}")) for i in range(start, end + 1)]
     found: Dict[str, str] = {}
 
-    with concurrent.futures.ThreadPoolExecutor(max_workers=max_workers) as pool:
-        futures = [pool.submit(ssh_hostname, ip, users, key_path, timeout_sec) for ip in scan_ips]
-        for fut in concurrent.futures.as_completed(futures):
-            result = fut.result()
-            if not result:
-                continue
-            host, ip = result
-            if host in target_names and host not in found:
-                found[host] = ip
-            if all(name in found for name in target_names):
-                break
+    seen_hostnames: Dict[str, str] = {}
+
+    def run_pass(pass_timeout: int, pass_workers: int) -> None:
+        with concurrent.futures.ThreadPoolExecutor(max_workers=pass_workers) as pool:
+            futures = [pool.submit(ssh_hostname, ip, users, key_path, pass_timeout) for ip in scan_ips]
+            for fut in concurrent.futures.as_completed(futures):
+                result = fut.result()
+                if not result:
+                    continue
+                host, ip = result
+                if host not in seen_hostnames:
+                    seen_hostnames[host] = ip
+                if host in target_names and host not in found:
+                    found[host] = ip
+                if all(name in found for name in target_names):
+                    return
+
+    run_pass(timeout_sec, max_workers)
+    if not all(name in found for name in target_names):
+        # Slower second pass for busy runners/networks.
+        run_pass(max(timeout_sec + 2, 8), max(8, max_workers // 2))
 
     missing = sorted([n for n in target_names if n not in found])
     if missing:
+        discovered = ", ".join(sorted(seen_hostnames.keys())[:20])
+        if discovered:
+            sys.stderr.write(f"Discovered hostnames during scan: {discovered}\n")
         raise SystemExit(
             "Failed SSH-based IP discovery for nodes: " + ", ".join(missing) +
             f" (scanned {prefix}.{start}-{prefix}.{end})"