html_url,issue_url,id,node_id,user,user_label,created_at,updated_at,author_association,body,reactions,issue,issue_label,performed_via_github_app
https://github.com/simonw/datasette/issues/873#issuecomment-650905399,https://api.github.com/repos/simonw/datasette/issues/873,650905399,MDEyOklzc3VlQ29tbWVudDY1MDkwNTM5OQ==,9599,simonw,2020-06-29T05:01:03Z,2020-06-29T05:01:03Z,OWNER,This is a bit tricky to fix. This change to uvicorn is relevant: https://github.com/encode/uvicorn/commit/a75fe1381f6b1f78901691c71894f3cf487b5d30,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",647095487,"""datasette -p 0 --root"" gives the wrong URL",
https://github.com/simonw/datasette/issues/873#issuecomment-650906318,https://api.github.com/repos/simonw/datasette/issues/873,650906318,MDEyOklzc3VlQ29tbWVudDY1MDkwNjMxOA==,9599,simonw,2020-06-29T05:04:04Z,2020-06-29T05:04:12Z,OWNER,"Within uvicorn it does this:
```python
            if port == 0:
                port = server.sockets[0].getsockname()[1]
```
That `server` variable is later stashed here:
```
self.servers = [server]
```
Where `self` is the instance of `class Server` - which is the class that Uvicorn instantiates and calls `.run()` on when we do `uvicorn.run()` here: https://github.com/simonw/datasette/blob/35aee82c60b2c9a0185b934db5528c8bd11830f2/datasette/cli.py#L409","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",647095487,"""datasette -p 0 --root"" gives the wrong URL",
https://github.com/simonw/datasette/issues/873#issuecomment-650906533,https://api.github.com/repos/simonw/datasette/issues/873,650906533,MDEyOklzc3VlQ29tbWVudDY1MDkwNjUzMw==,9599,simonw,2020-06-29T05:04:44Z,2020-06-29T05:04:44Z,OWNER,The challenge is... can we run our own custom code after that line has executed that has access to `server` and can hence access `server.servers[0].sockets[0].getsockname()[1]` to find the port?,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",647095487,"""datasette -p 0 --root"" gives the wrong URL",
https://github.com/simonw/datasette/issues/873#issuecomment-650907323,https://api.github.com/repos/simonw/datasette/issues/873,650907323,MDEyOklzc3VlQ29tbWVudDY1MDkwNzMyMw==,9599,simonw,2020-06-29T05:07:16Z,2020-06-29T05:07:16Z,OWNER,"This line is interesting: is this a hook I can attach to somehow?
```python
        await self.lifespan.startup()
```
From https://github.com/encode/uvicorn/blob/a75fe1381f6b1f78901691c71894f3cf487b5d30/uvicorn/main.py#L475","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",647095487,"""datasette -p 0 --root"" gives the wrong URL",
https://github.com/simonw/datasette/issues/873#issuecomment-650908534,https://api.github.com/repos/simonw/datasette/issues/873,650908534,MDEyOklzc3VlQ29tbWVudDY1MDkwODUzNA==,9599,simonw,2020-06-29T05:11:06Z,2020-06-29T05:11:06Z,OWNER,"Uvicorn's lifespan stuff isn't easy to figure out, but this test suite holds some clues: https://github.com/encode/uvicorn/blob/master/tests/test_lifespan.py","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",647095487,"""datasette -p 0 --root"" gives the wrong URL",
https://github.com/simonw/datasette/issues/873#issuecomment-650908854,https://api.github.com/repos/simonw/datasette/issues/873,650908854,MDEyOklzc3VlQ29tbWVudDY1MDkwODg1NA==,9599,simonw,2020-06-29T05:12:04Z,2020-06-29T05:12:04Z,OWNER,Can I detect the port the server is running on from within the regular Datasette ASGI code? If so I could use that ability and maybe output the magic `--root` link a second after the server starts up somehow.,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",647095487,"""datasette -p 0 --root"" gives the wrong URL",
https://github.com/simonw/datasette/issues/873#issuecomment-650909136,https://api.github.com/repos/simonw/datasette/issues/873,650909136,MDEyOklzc3VlQ29tbWVudDY1MDkwOTEzNg==,9599,simonw,2020-06-29T05:12:58Z,2020-06-29T05:12:58Z,OWNER,"On startup Datasette currently outputs:
```
INFO:     Waiting for application startup.
INFO:     ASGI 'lifespan' protocol appears unsupported.
INFO:     Application startup complete.
```
So the ASGI lifespan protocol is almost certainly the right way to solve this.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",647095487,"""datasette -p 0 --root"" gives the wrong URL",
https://github.com/simonw/datasette/issues/873#issuecomment-650909476,https://api.github.com/repos/simonw/datasette/issues/873,650909476,MDEyOklzc3VlQ29tbWVudDY1MDkwOTQ3Ng==,9599,simonw,2020-06-29T05:14:08Z,2020-06-29T05:14:08Z,OWNER,"I already have a `AsgiLifespan` class:
https://github.com/simonw/datasette/blob/35aee82c60b2c9a0185b934db5528c8bd11830f2/datasette/app.py#L896-L905

It runs this function: https://github.com/simonw/datasette/blob/35aee82c60b2c9a0185b934db5528c8bd11830f2/datasette/app.py#L890-L894

Could that startup function also output the `--root` login URL, if needed?","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",647095487,"""datasette -p 0 --root"" gives the wrong URL",
https://github.com/simonw/datasette/issues/873#issuecomment-650910137,https://api.github.com/repos/simonw/datasette/issues/873,650910137,MDEyOklzc3VlQ29tbWVudDY1MDkxMDEzNw==,9599,simonw,2020-06-29T05:16:32Z,2020-06-29T05:16:32Z,OWNER,I'm not convinced that function is ever actually being called - I added a `print()` statement to it and it's not executing. I don't think the tests cover it.,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",647095487,"""datasette -p 0 --root"" gives the wrong URL",
https://github.com/simonw/datasette/issues/873#issuecomment-651193131,https://api.github.com/repos/simonw/datasette/issues/873,651193131,MDEyOklzc3VlQ29tbWVudDY1MTE5MzEzMQ==,9599,simonw,2020-06-29T15:27:00Z,2020-06-29T15:27:00Z,OWNER,"Aha! Yes it's not being called, and the reason is this: https://github.com/encode/starlette/issues/486

Short version: by default an exception raised during that phase is silently swallowed! You can avoid the swallowing by adding `lifespan=""on""` to the call to `uvicorn.run()`.

When I did that here:

`uvicorn.run(ds.app(), host=host, port=port, log_level=""info"", lifespan=""on"")`

The server failed to start with this error:

```
INFO:     Started server process [68849]
INFO:     Waiting for application startup.
ERROR:    Exception in 'lifespan' protocol
Traceback (most recent call last):
  File "".../uvicorn/lifespan/on.py"", line 48, in main
    await app(scope, self.receive, self.send)
  File "".../uvicorn/middleware/proxy_headers.py"", line 45, in __call__
    return await self.app(scope, receive, send)
  File "".../datasette_debug_asgi.py"", line 9, in wrapped_app
    if scope[""path""] == ""/-/asgi-scope"":
KeyError: 'path'
```","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",647095487,"""datasette -p 0 --root"" gives the wrong URL",
https://github.com/simonw/datasette/issues/873#issuecomment-651193594,https://api.github.com/repos/simonw/datasette/issues/873,651193594,MDEyOklzc3VlQ29tbWVudDY1MTE5MzU5NA==,9599,simonw,2020-06-29T15:27:46Z,2020-06-29T15:27:46Z,OWNER,Uninstalling `datasette-debug-asgi` caused the server to startup correctly again.,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",647095487,"""datasette -p 0 --root"" gives the wrong URL",
https://github.com/simonw/datasette/issues/873#issuecomment-651203178,https://api.github.com/repos/simonw/datasette/issues/873,651203178,MDEyOklzc3VlQ29tbWVudDY1MTIwMzE3OA==,9599,simonw,2020-06-29T15:44:38Z,2020-06-29T15:44:54Z,OWNER,I'm having real trouble figuring out how to gain access to the port that was used to start the server. I'm treating this as a very low priority - it only affects the exact `-p 0 --root` combination which isn't going to affect many people at all.,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",647095487,"""datasette -p 0 --root"" gives the wrong URL",
https://github.com/simonw/datasette/issues/873#issuecomment-675609109,https://api.github.com/repos/simonw/datasette/issues/873,675609109,MDEyOklzc3VlQ29tbWVudDY3NTYwOTEwOQ==,9599,simonw,2020-08-18T17:21:51Z,2020-08-18T17:21:51Z,OWNER,Asked about this on the encode gitter here: https://gitter.im/encode/community?at=5f3c0dcaa8c17801765940c0,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",647095487,"""datasette -p 0 --root"" gives the wrong URL",
https://github.com/simonw/datasette/issues/873#issuecomment-675610275,https://api.github.com/repos/simonw/datasette/issues/873,675610275,MDEyOklzc3VlQ29tbWVudDY3NTYxMDI3NQ==,9599,simonw,2020-08-18T17:24:05Z,2020-08-18T17:26:10Z,OWNER,"Maybe I can do this with ASGI after all. Here's the output of `/-/asgi-scope` with `datasette-debug-asgi` installed:
```
{'asgi': {'spec_version': '2.1', 'version': '3.0'},
 'client': ('127.0.0.1', 62035),
 'headers': [(b'host', b'127.0.0.1:62029'),
             (b'user-agent',
              b'Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:79.0) Gecko'
              b'/20100101 Firefox/79.0'),
             (b'accept',
              b'text/html,application/xhtml+xml,application/xml;q=0.9,image/'
              b'webp,*/*;q=0.8'),
             (b'accept-language', b'en-US,en;q=0.5'),
             (b'accept-encoding', b'gzip, deflate'),
             (b'dnt', b'1'),
             (b'connection', b'keep-alive'),
             (b'upgrade-insecure-requests', b'1'),
             (b'cache-control', b'max-age=0')],
 'http_version': '1.1',
 'method': 'GET',
 'path': '/-/asgi-scope',
 'query_string': b'',
 'raw_path': b'/-/asgi-scope',
 'root_path': '',
 'scheme': 'http',
 'server': ('127.0.0.1', 62029),
 'type': 'http'}
```
That `'server': ('127.0.0.1', 62029)` bit has the correct port. Question is, can I access that programmatically on server startup?","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",647095487,"""datasette -p 0 --root"" gives the wrong URL",