cull_idle_servers syntax error

[d...@deej.net]

I'm trying to setup the cull idle service, and am running into the following error:

[I 2018-04-24 13:52:44.679 JupyterHub service:266] Starting service 'cull-idle': ['python3', '/etc/jupyterhub/cull_idle_servers.py', '--timeout=3600']
[I 2018-04-24 13:52:44.682 JupyterHub service:109] Spawning python3 /etc/jupyterhub/cull_idle_servers.py --timeout=3600
  File "/etc/jupyterhub/cull_idle_servers.py", line 78
    return f"{h:02}:{m:02}:{seconds:02}"
                                       ^
SyntaxError: invalid syntax


Running it directly from the command line returns the same error.

# python3 cull_idle_servers.py
  File "cull_idle_servers.py", line 78
    return f"{h:02}:{m:02}:{seconds:02}"
                                       ^
SyntaxError: invalid syntax


This is using the current file downloaded today from https://github.com/jupyterhub/jupyterhub/blob/master/examples/cull-idle/cull_idle_servers.py

Has anyone else run into this and have suggestions?

Thanks,

-Dj

[Tim Head]

Hi,

On Tue, Apr 24, 2018 at 7:56 PM <d...@deej.net> wrote:

I'm trying to setup the cull idle service, and am running into the following error: 

[I 2018-04-24 13:52:44.679 JupyterHub service:266] Starting service 'cull-idle': ['python3', '/etc/jupyterhub/cull_idle_servers.py', '--timeout=3600']
[I 2018-04-24 13:52:44.682 JupyterHub service:109] Spawning python3 /etc/jupyterhub/cull_idle_servers.py --timeout=3600
  File "/etc/jupyterhub/cull_idle_servers.py", line 78
    return f"{h:02}:{m:02}:{seconds:02}"
                                       ^
SyntaxError: invalid syntax

The cull_idle_servers.py script requires Python 3.6. It uses a new feature called fstrings (https://docs.python.org/3/whatsnew/3.6.html#pep-498-formatted-string-literals) 

T

[d...@deej.net]

Thanks, Tim, that would explain it.  We only have Python 3.4.8 available. 
Any chance there is an older version of the script that works with 3.4?
-Dj

[d...@deej.net]

As a followup to this, I ended up installing Python 3.6 via the Software Collections (we are running Centos 7.x), and am calling the script external to the Jupyterhub service using an API key and it is working fine as far as I can tell.

Thanks for the assist!

-Dj