Updated examples to automatically use random port (libp2p#661)

* updated examples to automatically use random port

* Refactor examples to use shared utils for port selection (libp2p#1)

---------

Co-authored-by: acul71 <34693171+acul71@users.noreply.github.com>

Author: lla-dane

examples/chat/chat.py

@@ -40,7 +40,6 @@ async def write_data(stream: INetStream) -> None:
 
 
 async def run(port: int, destination: str) -> None:
-    localhost_ip = "127.0.0.1"
     listen_addr = multiaddr.Multiaddr(f"/ip4/0.0.0.0/tcp/{port}")
     host = new_host()
     async with host.run(listen_addrs=[listen_addr]), trio.open_nursery() as nursery:
@@ -54,8 +53,8 @@ async def stream_handler(stream: INetStream) -> None:
 
             print(
                 "Run this from the same folder in another console:\n\n"
-                f"chat-demo -p {int(port) + 1} "
-                f"-d /ip4/{localhost_ip}/tcp/{port}/p2p/{host.get_id().pretty()}\n"
+                f"chat-demo "
+                f"-d {host.get_addrs()[0]}\n"
             )
             print("Waiting for incoming connection...")
 
@@ -87,9 +86,7 @@ def main() -> None:
         "/ip4/127.0.0.1/tcp/8000/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
     )
     parser = argparse.ArgumentParser(description=description)
-    parser.add_argument(
-        "-p", "--port", default=8000, type=int, help="source port number"
-    )
+    parser.add_argument("-p", "--port", default=0, type=int, help="source port number")
     parser.add_argument(
         "-d",
         "--destination",
@@ -98,9 +95,6 @@ def main() -> None:
     )
     args = parser.parse_args()
 
-    if not args.port:
-        raise RuntimeError("was not able to determine a local port")
-
     try:
         trio.run(run, *(args.port, args.destination))
     except KeyboardInterrupt:

examples/echo/echo.py

@@ -30,7 +30,6 @@ async def _echo_stream_handler(stream: INetStream) -> None:
 
 
 async def run(port: int, destination: str, seed: int | None = None) -> None:
-    localhost_ip = "127.0.0.1"
     listen_addr = multiaddr.Multiaddr(f"/ip4/0.0.0.0/tcp/{port}")
 
     if seed:
@@ -53,8 +52,8 @@ async def run(port: int, destination: str, seed: int | None = None) -> None:
 
             print(
                 "Run this from the same folder in another console:\n\n"
-                f"echo-demo -p {int(port) + 1} "
-                f"-d /ip4/{localhost_ip}/tcp/{port}/p2p/{host.get_id().pretty()}\n"
+                f"echo-demo "
+                f"-d {host.get_addrs()[0]}\n"
             )
             print("Waiting for incoming connections...")
             await trio.sleep_forever()
@@ -73,6 +72,7 @@ async def run(port: int, destination: str, seed: int | None = None) -> None:
             msg = b"hi, there!\n"
 
             await stream.write(msg)
+            # TODO: check why the stream is closed after the first write ???
             # Notify the other side about EOF
             await stream.close()
             response = await stream.read()
@@ -94,9 +94,7 @@ def main() -> None:
         "/ip4/127.0.0.1/tcp/8000/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
     )
     parser = argparse.ArgumentParser(description=description)
-    parser.add_argument(
-        "-p", "--port", default=8000, type=int, help="source port number"
-    )
+    parser.add_argument("-p", "--port", default=0, type=int, help="source port number")
     parser.add_argument(
         "-d",
         "--destination",
@@ -110,10 +108,6 @@ def main() -> None:
         help="provide a seed to the random number generator (e.g. to fix peer IDs across runs)",  # noqa: E501
     )
     args = parser.parse_args()
-
-    if not args.port:
-        raise RuntimeError("was not able to determine a local port")
-
     try:
         trio.run(run, args.port, args.destination, args.seed)
     except KeyboardInterrupt:

examples/identify/identify.py

@@ -61,20 +61,20 @@ async def run(port: int, destination: str) -> None:
         async with host_a.run(listen_addrs=[listen_addr]):
             print(
                 "First host listening. Run this from another console:\n\n"
-                f"identify-demo -p {int(port) + 1} "
-                f"-d /ip4/{localhost_ip}/tcp/{port}/p2p/{host_a.get_id().pretty()}\n"
+                f"identify-demo "
+                f"-d {host_a.get_addrs()[0]}\n"
             )
             print("Waiting for incoming identify request...")
             await trio.sleep_forever()
 
     else:
         # Create second host (dialer)
-        print(f"dialer (host_b) listening on /ip4/{localhost_ip}/tcp/{port}")
         listen_addr = multiaddr.Multiaddr(f"/ip4/{localhost_ip}/tcp/{port}")
         host_b = new_host()
 
         async with host_b.run(listen_addrs=[listen_addr]):
             # Connect to the first host
+            print(f"dialer (host_b) listening on {host_b.get_addrs()[0]}")
             maddr = multiaddr.Multiaddr(destination)
             info = info_from_p2p_addr(maddr)
             print(f"Second host connecting to peer: {info.peer_id}")
@@ -104,13 +104,11 @@ def main() -> None:
     """
 
     example_maddr = (
-        "/ip4/127.0.0.1/tcp/8888/p2p/QmQn4SwGkDZkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
+        "/ip4/127.0.0.1/tcp/8888/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
     )
 
     parser = argparse.ArgumentParser(description=description)
-    parser.add_argument(
-        "-p", "--port", default=8888, type=int, help="source port number"
-    )
+    parser.add_argument("-p", "--port", default=0, type=int, help="source port number")
     parser.add_argument(
         "-d",
         "--destination",
@@ -119,9 +117,6 @@ def main() -> None:
     )
     args = parser.parse_args()
 
-    if not args.port:
-        raise RuntimeError("failed to determine local port")
-
     try:
         trio.run(run, *(args.port, args.destination))
     except KeyboardInterrupt:

examples/identify_push/identify_push_listener_dialer.py

@@ -56,9 +56,6 @@
 # Configure logging
 logger = logging.getLogger("libp2p.identity.identify-push-example")
 
-# Default port configuration
-DEFAULT_PORT = 8888
-
 
 def custom_identify_push_handler_for(host):
     """
@@ -241,25 +238,16 @@ def main() -> None:
     """Parse arguments and start the appropriate mode."""
     description = """
     This program demonstrates the libp2p identify/push protocol.
-    Without arguments, it runs as a listener on port 8888.
-    With -d parameter, it runs as a dialer on port 8889.
+    Without arguments, it runs as a listener on random port.
+    With -d parameter, it runs as a dialer on random port.
     """
 
     example = (
-        f"/ip4/127.0.0.1/tcp/{DEFAULT_PORT}/p2p/"
-        "QmQn4SwGkDZkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
+        "/ip4/127.0.0.1/tcp/8000/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
     )
 
     parser = argparse.ArgumentParser(description=description)
-    parser.add_argument(
-        "-p",
-        "--port",
-        type=int,
-        help=(
-            f"port to listen on (default: {DEFAULT_PORT} for listener, "
-            f"{DEFAULT_PORT + 1} for dialer)"
-        ),
-    )
+    parser.add_argument("-p", "--port", default=0, type=int, help="source port number")
     parser.add_argument(
         "-d",
         "--destination",
@@ -270,13 +258,11 @@ def main() -> None:
 
     try:
         if args.destination:
-            # Run in dialer mode with default port DEFAULT_PORT + 1 if not specified
-            port = args.port if args.port is not None else DEFAULT_PORT + 1
-            trio.run(run_dialer, port, args.destination)
+            # Run in dialer mode with random available port if not specified
+            trio.run(run_dialer, args.port, args.destination)
         else:
-            # Run in listener mode with default port DEFAULT_PORT if not specified
-            port = args.port if args.port is not None else DEFAULT_PORT
-            trio.run(run_listener, port)
+            # Run in listener mode with random available port if not specified
+            trio.run(run_listener, args.port)
     except KeyboardInterrupt:
         print("\nInterrupted by user")
         logger.info("Interrupted by user")

examples/ping/ping.py

@@ -55,7 +55,6 @@ async def send_ping(stream: INetStream) -> None:
 
 
 async def run(port: int, destination: str) -> None:
-    localhost_ip = "127.0.0.1"
     listen_addr = multiaddr.Multiaddr(f"/ip4/0.0.0.0/tcp/{port}")
     host = new_host(listen_addrs=[listen_addr])
 
@@ -65,8 +64,8 @@ async def run(port: int, destination: str) -> None:
 
             print(
                 "Run this from the same folder in another console:\n\n"
-                f"ping-demo -p {int(port) + 1} "
-                f"-d /ip4/{localhost_ip}/tcp/{port}/p2p/{host.get_id().pretty()}\n"
+                f"ping-demo "
+                f"-d {host.get_addrs()[0]}\n"
             )
             print("Waiting for incoming connection...")
 
@@ -96,10 +95,8 @@ def main() -> None:
     )
 
     parser = argparse.ArgumentParser(description=description)
+    parser.add_argument("-p", "--port", default=0, type=int, help="source port number")
 
-    parser.add_argument(
-        "-p", "--port", default=8000, type=int, help="source port number"
-    )
     parser.add_argument(
         "-d",
         "--destination",
@@ -108,9 +105,6 @@ def main() -> None:
     )
     args = parser.parse_args()
 
-    if not args.port:
-        raise RuntimeError("failed to determine local port")
-
     try:
         trio.run(run, *(args.port, args.destination))
     except KeyboardInterrupt:

newsfragments/661.docs.rst

@@ -0,0 +1 @@
+Updated examples to automatically use random port, when `-p` flag is not given