phantomjs - Why does my Python subprocess error when managed by supervisord? -


i wrote small api screen captures - flask app passes capture requests casperjs using subprocess.popen

in development on mac, , when run server in shell on production server ubuntu 13.04 - works great.

when manage server supervisord, however, subprocess call returns error casperjs cannot find phantomjs (casper runs on phantom).

the error thrown is:

fatal: [errno 2] no such file or directory; did install phantomjs?

the code open source.

here subprocess call:

https://github.com/pwalsh/moment/blob/master/moment/models.py#l215

here supervisor conf file server (i generate actual file fabric, should clear):

https://github.com/pwalsh/moment/blob/master/fabfile/templates.py#l56

there 2 users on system - root, , app's user. when log on machine either of these users, can run dev server successfully, , can run phantomjs , casperjs successfully.

why subprocess error supervisord?

edit: adding code + stacktrace

supervisord conf gunicorn server:

; generated via fabric on 2013-08-18 23:05:50.928087 ; gunicorn configuration moment [program:moment-gunicorn]  command=/srv/environments/moment/bin/gunicorn moment:app --bind 127.0.0.1:9000 --workers 4 --timeout 30 --access-logfile /srv/logs/moment_gunicorn_access.log --error-logfile /srv/logs/moment_gunicorn_error.log  environment=path="/srv/environments/moment/bin" directory=/srv/projects/moment user=moment autostart=true autorestart=true

the code sends data casperjs/phantomjs subprocess. method of class, full code here:

def capture(self):      filename = '{key}.{format}'.format(key=self.get_key().lstrip(self.prefix),                                       format=self.arguments['format'])      image = os.path.join(conf.captures_root, filename)      params = [conf.casper, conf.capture_script, self.arguments['url'],               image, self.arguments['viewport'], self.arguments['target']]      casper = subprocess.popen(params, stdout=subprocess.pipe,                               stderr=subprocess.pipe)      casper_output, casper_errors = casper.communicate()      logging.info(casper_output)     logging.info(casper_errors)     logging.info(casper.returncode)      # here relying on convention:     # if success, subprocess.returncode == 0     # fragile, need investigate.     if casper.returncode:          raise exception(casper_errors)      else:          return image

traceback:

warning:root:fatal: [errno 2] no such file or directory; did install phantomjs? warning:root: warning:root:1 error:moment:exception on /capture/ [get] traceback (most recent call last):   file "/srv/environments/moment/local/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app response = self.full_dispatch_request() file "/srv/environments/moment/local/lib/python2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request rv = self.handle_user_exception(e) file "/srv/environments/moment/local/lib/python2.7/site-packages/flask/app.py", line 1381, in handle_user_exception reraise(exc_type, exc_value, tb) file "/srv/environments/moment/local/lib/python2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request rv = self.dispatch_request() file "/srv/environments/moment/local/lib/python2.7/site-packages/flask/app.py", line 1461, in dispatch_request return self.view_functions[rule.endpoint](**req.view_args) file "/srv/projects/moment/moment/views.py", line 45, in get_capture image = capture.capture() file "/srv/projects/moment/moment/models.py", line 229, in capture raise exception(casper_errors) exception

note:

  • i running in virtualenv called "moment", , under user called "moment".
  • the error in casper_output variable - first 3 warning warning log when start subprocess
  • i note warning raised root - i'd have expected them raised "moment", user supervisord process supposed run as

although (for reasons should investigate) user has escalated original moment user root, not mean process has environment present when login shell root.

the chances path set in supervisord.conf, , that's why phantomjs appears absent.

environments not looked in database of users; instead constructed explicitly setting values (e.g. using script) or inheritance spawning process. in case, inheriting supervisor, , whatever environment supervisor had. if supervisor run cron, environment empty.

best practice in relation supervisor either run using wrapper script sets environment correctly, or explicitly set in supervisord.conf. recommend latter, unless have common set of environment fixups in file used lot of scripts (such because want run inside virtualenv).


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