WSGIDaemonProcess: specifying a user

Question

I have a user account all set up for this Python webapp I'm deploying with mod_wsgi. It's super-unprivileged, and only gets to read from the appdir and write to a separate set of tempdirs which no one else gets to look at. I'm using the following configline:

WSGIDaemonProcess xlsxf_daemon user=xlsxf group=xlsxf

Simple enough. Unfortunately, we then have this from the docs about the user option:

Note that this option is ignored if Apache wasn't started as the root user, in which case no matter what the settings, the daemon processes will be run as the user that Apache was started as.

Since I'm running this in a default Ubuntu install on Linode, Apache starts as the www-data user and the Python app I have confirmed is doomed to also run as www-data. Why the limitation above? I have plenty of ruby/passenger apps that daemonize as other users just fine.

edit: okay, so Apache doesn't start as the www-data user, but I'm still seeing that the Python webapp runs as www-data in spite of the above config line. /edit

Alternatively, am I just being overly paranoid here? I have multiple different projects running on this server, and I'd like them all to run as separate users, "just in case", but feel free to tell me that I should just give in and move the permissions over to www-data.

edit2: As requested, here's all the running apache processes:

root     18798  0.0  1.9  16156  9880 ?        Ss   Jul26   0:03 /usr/sbin/apache2 -k start
www-data 19344  0.0  1.0  15208  5264 ?        S    Jul26   0:00 /usr/sbin/apache2 -k start
xlsxf    19361  0.0  1.2 155244  6620 ?        Sl   Jul26   0:02 /usr/sbin/apache2 -k start
www-data 19379  0.0  3.2 245436 16420 ?        Sl   Jul26   0:01 /usr/sbin/apache2 -k start
www-data 19380  0.0  3.2 243536 16496 ?        Sl   Jul26   0:01 /usr/sbin/apache2 -k start

Solution

You are reading it wrong. Apache does start as 'root' and the parent Apache process stays as 'root', only the Apache server child process run as 'www-data'. The mod_wsgi daemon processes are forked from the parent 'root' process and so will still be able to change to that user.

What the comment is saying is that if you start Apache from a totally non privileged account, eg., as you out of an install of Apache in your home directory or elsewhere, then since it doesn't start as 'root' it can't change user id of daemon processes. Apache started from system init scripts though is always started as 'root' though and should be no issue.

Comments

[issa marie tseng]

I believe what you're saying, but what I'm seeing is that despite the above config line, the Python webprocess is still starting up as www-data. Any thoughts about why that may be? Thanks!

[Graham Dumpleton]

Do a 'ps auxwwww | grep httpd' and add the result to your question. Process may also be called 'apache2'. Don't remember what Ubuntu calls it.

[issa marie tseng]

So, there is an apache2 process running under the xlsxf user, but this was actually what made it so difficult to figure out what was going on in the first place: despite the existence of that process, wherever the actual Python app is running, the user is still www-data (reads/writes files as that user; returns that username when I do a getpass.getuser()). Perhaps something else is wrong with my config then?

[Graham Dumpleton]

Then you are missing WSGIProcessGroup in your configuration. Review the instructions at code.google.com/p/modwsgi/wiki/…

[issa marie tseng]

Bam. Thank you. I wish I could give you more points.

[issa marie tseng]

Okay, now I wish I could give you even more points, since blog.dscpl.com.au/2009/04/… just covered the next problem I ran into via Google. (I didn't develop this Python app [I'm a Rubyist], and the person who did hasn't done web programming before...). So thanks again.

[Graham Dumpleton]

For reference, to check whether daemon mode used or not, see code.google.com/p/modwsgi/wiki/…