[ome-users] sessionid files in /tmp

Wed Jun 25 18:40:11 BST 2014

Hi John,

You probably already know this, or would have come across it anyway, but I
would just like to add that if you do go down the route of Memcached (as a
cache backend on a single host) then it¹s port should be firewalled off
from the rest of the network. There is no authentication required by
default, so any user that can access the Memcached port of 11211 can
read/write to the cache and clear the entire cache via telnet.

See http://blog.couchbase.com/memcached-security for more information.

Best regards,

Kenny

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Kenneth Gillen

OME System Administrator

Wellcome Trust Centre for Gene Regulation & Expression
College of Life Sciences
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University of Dundee
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Dundee  DD1 5EH
United Kingdom

Tel: +44 (0) 1382 386364
Skype: kennethgillen

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From:  Aleksandra Tarkowska <A.Tarkowska at dundee.ac.uk>
Date:  Wednesday, 25 June 2014 15:08
To:  "John Webber (NBI)" <John.Webber at nbi.ac.uk>
Cc:  "ome-users at lists.openmicroscopy.org.uk"
<ome-users at lists.openmicroscopy.org.uk>
Subject:  Re: [ome-users] sessionid files in /tmp

Dear John

As users create new sessions on the OMERO.web, session data can accumulate
in your session store. Because OMERO.web uses the file based backend, your
temporary directory will contain an increasing number of files. Django
does not provide automatic purging of
 expired sessions. Therefore, it¹s your job to purge expired sessions on a
regular basis. Django provides a clean-up management command for this
purpose: clear sessions. It¹s recommended to call this command on a
regular basis, for example as a daily cron job.

cd OMERO/lib/python/omeroweb
python manage.py clearsessions

Note that the cache backend isn¹t vulnerable to this problem, because
caches automatically delete stale data.
If you wish to change it to cache based, first install
 Memcached  and a memcached binding. There are several python memcached
bindings available; the two most common are python-memcached and pylibmc.
Then set the following

$ bin/omero web stop
$ bin/omero config set omero.web.caches '{"default": { "BACKEND":
"django.core.cache.backends.memcached.MemcachedCache", "LOCATION":
"127.0.0.1:11211", "TIMEOUT": "86400" } }'
$ bin/omero config set omero.web.session_engine
"django.contrib.sessions.backends.cache"
$ bin/omero web start

I hope it will help

Kind regards

Ola

From: "John Webber (NBI)" <John.Webber at nbi.ac.uk>
Date: Mon, 23 Jun 2014 11:20:08 +0000
To: William Moore <will at lifesci.dundee.ac.uk>
Cc: "ome-users at lists.openmicroscopy.org.uk"
<ome-users at lists.openmicroscopy.org.uk>
Subject: Re: [ome-users] sessionid files in /tmp

Hi Will,

Thanks for the response.

I have done some more tests but am still experiencing the same issue.  I
have restarted HTTPD, Omero and Omero_web.  I have also rebooted the server
 itself.

These files are created when we restart omero web.  When omero web is not
running the files are not created.

I am running exactly the same python versions, omero versions and ice
versions across two servers.  The main difference I can see on these
servers
 is that the one which has ³sessionid² files gathering in ³/tmp² has a
later version of httpd as follows:

                Server without issue:
               Server with sessionID issue:
httpd-2.2.3-82.el5.centos
httpd-2.2.3-83.el5.centos
httpd-devel-2.2.3-82.el5.centos
    httpd-devel-2.2.3-83.el5.centos

I have attached a complete list of the different RPMs, but not sure
whether any of the others are relevant.

Please can you give me a pointer as to why this is occurring.  Is it
something that can be corrected, or do I need to set up a cron job to
remove
 the session ID files?

Thanks
John

From: William Moore [mailto:will at lifesci.dundee.ac.uk]

Sent: 20 June 2014 10:46
To: John Webber (NBI)
Cc: ome-users at lists.openmicroscopy.org.uk
Subject: Re: [ome-users] sessionid files in /tmp

Hi John,

 It's probably the Django web server that is creating these files in /tmp.
See
https://docs.djangoproject.com/en/dev/topics/http/sessions/#using-file-base
d-sessions

and
http://stackoverflow.com/questions/10197880/django-file-based-session-doesn
t-expire

These are sessions between the browser and the Django server and have
nothing to do with OMERO sessions.

Are you aware of any difference in the web server configurations or
browser connections between your servers that could explain this behaviour?

 Regards,

   Will.

On 19 Jun 2014, at 16:38, "John Webber (NBI)" <John.Webber at nbi.ac.uk>
wrote:

Hi all,

On one of my Omero servers I am seeing ³sessionid² files in /tmp, which
are generated every 10 minutes and not removed. These files are called
something like ³sessionideb93037246a7b1efe7e01f6eec735cef².
 On other Omero servers, one or two of these files might exist, but they
are not created every 10 minutes or so!  These are only small, but there
are a lot of them!

Can anyone advise why these are being left behind?  This is the SAME
server where I was experiencing the ³Server
 error[500]² errors, which have now stopped.

Thanks

John

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