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OMERO.Web with mod_wsgi

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OMERO.Web with mod_wsgi

Postby ingvar » Fri May 11, 2012 1:17 pm


When I asked one of our system's guys to add the mod_fastcgi module to a server, his reply was rather not. He suggested that I use mod_wsgi instead, and described mod_fastcgi as outdated, and that installing it could in some way interfere with other things.

Do anyone have a recipe for how to install mod_wsgi along the lines on: http://www.openmicroscopy.org/site/supp ... nstall_web
I am on a RHEL6 machine if that matters.
I have seen some users mention that they use mod_wsgi. Apache configuration is not my strong point, I better ask for some help before attempting to switch.

Kind Regards,
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Re: OMERO.Web with mod_wsgi

Postby ingvar » Tue May 15, 2012 10:27 am

I managed to talk my friendly system's guy around to install mod_fastcgi. Not to happy about it, mentioning conflicting dependency trees. From various net comments I get the impression that mod_fastcgi has not been maintained for 5+ years, apart from that rpm's are created for new OS versions.

I did not see any easy way to use mod_wsgi as a replacement for mod_fastcgi, so will not try to pursue that venue.

However, I run across mod_proxy_fcgi, which is part of Apache 2.4, that looks like it provides the corresponding functionality. It may be useful to add a way to generate a stanza for mod_proxy_fcgi by the time Apache 2.4 becomes the default version in rpm's, say for OMERO 4.5/5.0.

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Re: OMERO.Web with mod_wsgi

Postby ckm » Tue May 15, 2012 5:31 pm

For RHEL6/CENTOS6 mod_fastcgi rpms are availble from rpmforge. In the past their repositories had a lot of conflicting dependencies and caused a lot of problems. With their rhel6 repositories they don't conflict with anything upstream anymore so they are pretty safe to install along side other repositories such as epel, etc.

OMERO.web handles all of it's fastcgi workers, threading, permissions etc (controlled by omero web start), to avoid a lot of inherent problems with permissions. It is likely possible to run it as a fastcgi application under mod_fcgid (which does not support an external daemon), but you'd be on your own with that configuration, as with mod_wsgi. You'd also likely have to get to configure mod_suexec as well.

When apache 2.4 is a bit more stable and some of the uncertainty around configuration changes and directive support is settled supporting mod_proxy_fcgid will likely be possible and on our test agenda, but till apache 2.4 makes it into some of the upstream distros it won't be on the radar.

If mod_fastcgi is untenable for your sysadmin, the next best option is to use another webserver that has native support for fastcgi. Nginx (available though a bit old @ rpmforge) and lighttpd.
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