Proper error messages on npm and port check failures, avoid leaking asyncio tasks.

template/scripts/devserver.py

@@ -41,7 +41,6 @@ async def run_devserver(
 
     viteurl, npm_install, vite = setup_vite(listen, DEFAULT_VITE_PORT)
     backurl, MODULE_NAME = setup_cli("PROJECT_CLI", backend, DEFAULT_DEV_PORT)
-    await check_ports_free(viteurl, backurl)
 
     # Tell everyone via environment (vite proxy and backend devmode use these)
     os.environ["ENVPREFIX_VITE_URL"] = viteurl
@@ -49,6 +48,7 @@ async def run_devserver(
     os.environ["ENVPREFIX_DEV"] = "1"
 
     async with ProcessGroup() as pg:
+        pg.create_task(check_ports_free(viteurl, backurl))
         npm_i = await pg.spawn(*npm_install, cwd=front)
         await pg.spawn(*MODULE_NAME, *(extra_args or []), vital=True)
         await pg.wait(npm_i, ready(backurl, path=HEALTH))
@@ -78,9 +78,9 @@ def main() -> None:
     try:
         asyncio.run(run_devserver(args.listen, args.backend, extra_args))
     except* KeyboardInterrupt:
-        pass  # user stopped the devserver: exit 0
-    except* subprocess.SubprocessError:
-        raise SystemExit(1) from None  # error already logged; exit 1
+        pass  # user stopped the devserver: normal exit
+    except* (subprocess.SubprocessError, RuntimeError):
+        raise SystemExit(1) from None  # logged in devutil already; exit 1
 
 
 HELP_EPILOG = """

template/scripts/fastapi-vue/devutil.py

@@ -65,7 +65,9 @@ class ProcessGroup(asyncio.TaskGroup):
             if not isinstance(w, Process):
                 return await w
             if retcode := await w.wait():
-                raise CalledProcessError(retcode, self._cmds[w])
+                cmd = self._cmds[w]
+                logger.warning("Process %s exited with status %d", Path(cmd[0]).stem, retcode)
+                raise CalledProcessError(retcode, cmd)
             return retcode
 
         async with asyncio.TaskGroup() as group:
@@ -104,22 +106,23 @@ async def http_get_server(url: str, timeout: float) -> str | None:  # noqa: ASYN
 
 
 async def check_ports_free(*urls: str) -> None:
-    """Verify URLs are not responding (ports are free). Raise SystemExit if any respond."""
+    """Verify URLs are not responding (ports are free).
 
-    async def check(url: str) -> None:
-        server = await http_get_server(url, timeout=0.1)
+    Meant to run as a task inside a TaskGroup. Logs the conflict and raises
+    RuntimeError (handled like a failed process) if any URL responds.
+    """
+    servers = await asyncio.gather(*(http_get_server(url, timeout=0.1) for url in urls))
+    for url, server in zip(urls, servers, strict=True):
         if server is not None:
-            logger.warning("Conflicting %s already running at %s", server or "server", url)
-            raise SystemExit(1)
-
-    await asyncio.gather(*[check(url) for url in urls])
+            logger.error("Conflicting %s already running at %s", server or "server", url)
+            raise RuntimeError(url)
 
 
 async def ready(url: str, path: str = "", max_attempts: int = 50) -> None:
     """Wait for the server to be ready by polling an endpoint.
 
     Use empty path to disable the check and make this return immediately.
-    Raises SystemExit(1) if server doesn't start in time.
+    Raises TimeoutError if server doesn't start in time.
     """
     if not path:
         return
@@ -129,8 +132,7 @@ async def ready(url: str, path: str = "", max_attempts: int = 50) -> None:
             logger.info("✓ Backend ready!")
             return
         if attempt == max_attempts - 1:
-            logger.warning("Backend didn't start in time")
-            raise SystemExit(1)
+            raise TimeoutError(f"Backend at {url} didn't start in time")  # noqa: EM102, TRY003
         await asyncio.sleep(0.1)