Launch jlab with asynchronous=True

[mnlevy1981]

I think piping the output to a log file is necessary so we can grab the port and token; for now I'm just printing the log file to stdout in a separate run command to show that asynchronous is working correctly.

Fixes #3

[mnlevy1981]

I opted to name the Promise object returned from session.run(..., asynchronous=True) because I assume we'll need that at some point to kill the job. It's currently unused, though.

[mnlevy1981]

@andersy005 I ran into errors the two times I tried to run your script:

$ jupyter-forward start hobart --conda-env jlab
Password:
DEBUG: jlab_exe is of type <class 'invoke.runners.Promise'>

    To access the notebook, open this file in a browser:
        file:///home/mlevy/.local/share/jupyter/runtime/nbserver-34383-open.html
    Or copy and paste one of these URLs:
        http://hobart.cgd.ucar.edu:59583/?token=TOKEN
     or http://127.0.0.1:59583/?token=TOKEN
[I 17:55:39.443 LabApp] 302 GET /?token=TOKEN (128.117.68.33) 0.92ms
[W 17:55:41.626 LabApp] Could not determine jupyterlab build status without nodejs
[C 17:56:51.451 LabApp] received signal 15, stopping
[I 17:56:51.454 LabApp] Shutting down 0 kernels

Note that port=59628 and the contents of the logfile are:

$ cat .jforward.59628
[I 09:46:26.902 LabApp] [nb_conda_kernels] enabled, 2 kernels found
[I 09:46:31.174 LabApp] The port 59628 is already in use, trying another port.
[I 09:46:31.489 LabApp] [jupyter_nbextensions_configurator] enabled 0.4.1
[I 09:46:34.029 LabApp] JupyterLab extension loaded from /project/oce/mlevy/miniconda3/envs/jlab/lib/python3.7/site-packages/jupyterlab
[I 09:46:34.029 LabApp] JupyterLab application directory is /project/oce/mlevy/miniconda3/envs/jlab/share/jupyter/lab
[I 09:46:34.034 LabApp] Serving notebooks from local directory: /home/mlevy
[I 09:46:34.034 LabApp] The Jupyter Notebook is running at:
[I 09:46:34.034 LabApp] http://hobart.cgd.ucar.edu:59629/?token=TOKEN
[I 09:46:34.034 LabApp]  or http://127.0.0.1:59629/?token=TOKEN
[I 09:46:34.034 LabApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
[C 09:46:34.057 LabApp]

    To access the notebook, open this file in a browser:
        file:///home/mlevy/.local/share/jupyter/runtime/nbserver-51699-open.html
    Or copy and paste one of these URLs:
        http://hobart.cgd.ucar.edu:59629/?token=TOKEN
     or http://127.0.0.1:59629/?token=TOKEN

The process was still running on hobart, but I couldn't access it via port 59629. After killing that process, I tried specifying a port:

$ jupyter-forward start hobart --conda-env jlab --port 8899
Password:
DEBUG: jlab_exe is of type <class 'invoke.runners.Promise'>
tail: cannot open ‘/home/mlevy/.jforward.8899’ for reading: No such file or directory
Traceback (most recent call last):
  File "/Users/mlevy/miniconda3/envs/jupyter_forward/bin/jupyter-forward", line 33, in <module>
    sys.exit(load_entry_point('jupyter-forward', 'console_scripts', 'jupyter-forward')())
  File "/Users/mlevy/NO_BACKUP/codes/jupyter-forward/jupyter_forward/core.py", line 117, in main
    typer.run(app())
  File "/Users/mlevy/miniconda3/envs/jupyter_forward/lib/python3.7/site-packages/typer/main.py", line 214, in __call__
    return get_command(self)(*args, **kwargs)
  File "/Users/mlevy/miniconda3/envs/jupyter_forward/lib/python3.7/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/Users/mlevy/miniconda3/envs/jupyter_forward/lib/python3.7/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/Users/mlevy/miniconda3/envs/jupyter_forward/lib/python3.7/site-packages/click/core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/Users/mlevy/miniconda3/envs/jupyter_forward/lib/python3.7/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/Users/mlevy/miniconda3/envs/jupyter_forward/lib/python3.7/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/Users/mlevy/miniconda3/envs/jupyter_forward/lib/python3.7/site-packages/typer/main.py", line 497, in wrapper
    return callback(**use_params)  # type: ignore
  File "/Users/mlevy/NO_BACKUP/codes/jupyter-forward/jupyter_forward/core.py", line 94, in start
    result = session.run(f'tail {logfile}', hide='out')
  File "<decorator-gen-3>", line 2, in run
  File "/Users/mlevy/miniconda3/envs/jupyter_forward/lib/python3.7/site-packages/fabric/connection.py", line 30, in opens
    return method(self, *args, **kwargs)
  File "/Users/mlevy/miniconda3/envs/jupyter_forward/lib/python3.7/site-packages/fabric/connection.py", line 721, in run
    return self._run(self._remote_runner(), command, **kwargs)
  File "/Users/mlevy/miniconda3/envs/jupyter_forward/lib/python3.7/site-packages/invoke/context.py", line 101, in _run
    return runner.run(command, **kwargs)
  File "/Users/mlevy/miniconda3/envs/jupyter_forward/lib/python3.7/site-packages/invoke/runners.py", line 363, in run
    return self._run_body(command, **kwargs)
  File "/Users/mlevy/miniconda3/envs/jupyter_forward/lib/python3.7/site-packages/invoke/runners.py", line 422, in _run_body
    return self.make_promise() if self._asynchronous else self._finish()
  File "/Users/mlevy/miniconda3/envs/jupyter_forward/lib/python3.7/site-packages/invoke/runners.py", line 489, in _finish
    raise UnexpectedExit(result)
invoke.exceptions.UnexpectedExit: Encountered a bad command exit code!

Command: 'tail ~/.jforward.8899'

Exit code: 1

Stdout:



Stderr: already printed

That's the error I was getting when I put the 1 second sleep in, and I'm surprised your while statement didn't prevent it. I'm about to push a commit to address the second error, not sure what to make of the first. One possibility is that I forgot to delete the old logfile, and the tail command picked up the old file before the new one was generated?

[mnlevy1981]

7bf6b0c resolves the second error I was seeing:

$ jupyter-forward start hobart --conda-env jlab --port 8899
Password:
DEBUG: jlab_exe is of type <class 'invoke.runners.Promise'>
tail: cannot open ‘/home/mlevy/.jforward.8899’ for reading: No such file or directory
Trying to access ~/.jforward.8899 on hobart again...
[I 10:04:20.098 LabApp] http://hobart.cgd.ucar.edu:8899/?token=TOKEN
[I 10:04:20.098 LabApp]  or http://127.0.0.1:8899/?token=TOKEN
[I 10:04:20.098 LabApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
[C 10:04:20.106 LabApp]

    To access the notebook, open this file in a browser:
        file:///home/mlevy/.local/share/jupyter/runtime/nbserver-56388-open.html
    Or copy and paste one of these URLs:
        http://hobart.cgd.ucar.edu:8899/?token=TOKEN
     or http://127.0.0.1:8899/?token=TOKEN

[andersy005]

This looks great, @mnlevy1981 ! I am going to merge it. If there's anything missing, we can revisit in a separate PR.