Add support for autolaunching the browser

src/conductor/cli/explorer.py

@@ -20,13 +20,20 @@ def register_command(subparsers):
         default=8000,
         help="The port to listen on when serving the explorer.",
     )
+    parser.add_argument(
+        "--no-browser",
+        action="store_true",
+        help="If set, do not automatically start the web browser.",
+    )
     parser.set_defaults(func=main)
 
 
 @cli_command
 def main(args):
     try:
-        start_explorer(host=args.host, port=args.port)
+        start_explorer(
+            host=args.host, port=args.port, launch_browser=not args.no_browser
+        )
     except ConductorAbort:
         # We ignore this exception because it is raised when the user hits
         # Ctrl+C to shut down the server.

src/conductor/explorer/explorer.py

@@ -1,7 +1,10 @@
+import time
+import webbrowser
+import threading
 from conductor.errors import MissingExplorerSupport
 
 
-def start_explorer(host: str, port: int) -> None:
+def start_explorer(host: str, port: int, launch_browser: bool) -> None:
     """
     Entrypoint to launching Conductor's explorer. This function will attempt to
     start the explorer. If the user has not installed the necessary
@@ -12,14 +15,41 @@ def start_explorer(host: str, port: int) -> None:
     # user has not installed Conductor's UI dependencies.
     try:
         import uvicorn
-
-        uvicorn_config = uvicorn.Config(
-            "conductor.explorer.routes:app",
-            host=host,
-            port=port,
-            log_level="info",
-        )
-        server = uvicorn.Server(uvicorn_config)
-        server.run()
     except ImportError as ex:
         raise MissingExplorerSupport() from ex
+
+    uvicorn_config = uvicorn.Config(
+        "conductor.explorer.routes:app",
+        host=host,
+        port=port,
+        log_level="info",
+    )
+    server = uvicorn.Server(uvicorn_config)
+
+    # Start the server and launch the browser if requested.
+    try:
+        if launch_browser:
+            launch_thread = threading.Thread(
+                target=_launch_browser, args=(host, port, 1)
+            )
+            launch_thread.start()
+        else:
+            launch_thread = None
+
+        server.run()
+    finally:
+        if launch_thread is not None:
+            launch_thread.join()
+
+
+def _launch_browser(host: str, port: int, wait_s: int) -> None:
+    """
+    Launches the user's default browser to the Conductor explorer's URL.
+    """
+    # We want to start the web browser after the server has started.
+    # Unfortunately, uvicorn does not provide any nice "callback"-like
+    # mechanisms to know when it has started. So we use this heuristic approach
+    # of waiting for a few seconds. This is ugly, but keeps things simple
+    # without overengineering something meant to be cosmetic.
+    time.sleep(wait_s)
+    webbrowser.open(f"http://{host}:{port}")

website/docs/cli/explorer.md

@@ -23,6 +23,12 @@ will be port 8000.
 The host that Conductor's explorer tool will bind to. If unspecified, this will
 be `localhost`. Generally, you will not need to modify this value.
 
+### `--no-browser`
+
+If set, Conductor will not automatically launch a web browser. By default, this
+explorer command will start a web browser pointed at the explorer's web
+interface.
+
 ### `-h` or `--help`
 
 Prints a help message that provides details about how to use the `cond explorer`