I have a webapp (nginx, gunicorn, python) that receives git post hooks and triggers a command line tool (ruby, capistrano). Everything is run via a user named deployer. The command line tool runs very well and can connect via ssh to remote servers.

When the webapp triggers it, it can't connect via ssh. A password is required. I think I know how to circumvent it (i had a similar problem with cronjobs here: Server gets killed due to increasing number of ssh-agent processes) but somehow the user is empty in the webabb.

Given this script:

echo "$(whoami)"

When I run deployer@tools:/srv/deployment$ ./test > test.txt then test.txt contains "deployer" and the file test.txt is owned by deployer:deployer.

When I run the very same command from within my webapp then test.txt is empty (only containing a line break) but owned by deployer:www-data (as expected and configured in gunicorn).

How is that even possible and what may I do about that?

  • 2
    But.. why are you running echo $(whoami) instead of just whoami? And when you say you ran the very same command from the app, how did you do that? – muru Oct 11 '15 at 14:33
  • whoami brings the same result (without the linebreak, just an empty file and i run it with os.system('cd /srv/deployment && ./test > test.txt') from within the python app. – shredding Oct 11 '15 at 14:35
  • What if you run os.system('whoami > test.txt'), or use id -u instead of whoami, or use echo $USER? – muru Oct 11 '15 at 14:37
  • Interestingly whoami pure returns 127 instead of 0 as return code. – shredding Oct 11 '15 at 14:39
  • 2
    What's the PATH in your webapp? What if you give full path to whoami (/usr/bin/whoami, IIRC)? – muru Oct 11 '15 at 14:40

So the problem turned out to be a different path setting.

Gunicorn was using the python virtualenv as PATH and therefore did not know whoami at all. Pushing in absolute path worked!

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