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Twirrim_94896's avatar
Twirrim_94896
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Mar 29, 2011

struggling to create irules

I'm using python 2.6.6 and pycontrol 2.0.1 to connect to our load balancer and configure it. I'm trying to make a rough start at creating a standard provisioning script for any new subdomains that are set up. I like python/pycontrol in general it's proving fairly easy and simple to get things rolling (particularly in comparison to the usual PITA that seems to go with Perl & APIs), I'm able to pull all sorts of data from the LBs with ease.

I'm going to keep hacking away at this and will update if I manage to solve this in case it's useful to others. The examples I've been able to find so far don't seem to show python creating irules.

!/usr/bin/python

Import pycontrol and connect to loadbalancer

import pycontrol.pycontrol as pc

myLTM = pc.BIGIP(

hostname = 'serv.er.addre.ss',

username = 'admin',

password = 'password',

fromurl=True,

wsdls = ['LocalLB.Rule'])

Provide rl as a shortcut to the rules service

rl=myLTM.LocalLB.Rule

Query the user for the domain

appname = raw_input("Enter new application/subdomain name:")

Generate the content of the new iRule

irules_content = []

irules_content.append(u' Rule generated for %s' % appname)

irules_content.append(u'when HTTP_REQUEST {')

irules_content.append(u' Check if Host header is %s.ourdomain.com' % appname)

irules_content.append(u' if {[HTTP::host] eq "%s.ourdomain.com"}{' % appname)

irules_content.append(u' use %s pool' % appname)

irules_content.append(u' pool %s_pool' % appname)

irules_content.append(u' }')

irules_content.append(u'}')

Combine it all into a single \n separated string

irules_content = '\n'.join(irules_content)

Define the name for the iRule

irule_name = appname+"_redirect"

Print to screen

print irule_name

print irules_content

Attempt to create rule

rl.create(rule_name = irule_name, rules = irules_content)

Double check for sanity

double_check = rl.query_rule(rule_names = [irules_name])

print "\nCreated iRule:\n"

print double_check[0].rule_definition

Whilst rl.create appears to work, no exception is reported, double_check fails telling me the requested rule wasn't found. I don't see any way to commit changes to the interface. I'm sure it's the "rules = " bit that is wrong, if I use rule_definition that I'd expect to use there, it fails telling me rules wasn't there:

"WebFault: Server raised fault: 'Could not find element by name: rules'"

edit: Really not keen on this forum software.. just doesn't want to accept code tags around the code, seems to expect me to prepend [ code ] to every line?! (minus the spaces)

devops
iControl
python icontrol library

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  • Twirrim_94896's avatar
    Twirrim_94896
    Icon for Nimbostratus rankNimbostratus
    Mar 29, 2011

    Bah.. after struggling with this for a good while today, inspiration struck just after posting this..

    Need to define a dictionary (dict) object and pass that to the iRule create command:

     

     Attempt to create rule
irule_def = dict(rule_name=irule_name,rule_definition = irules_content)
rl.create(rules=[irule_def])

     

  • L4L7_53191's avatar
    L4L7_53191
    Icon for Nimbostratus rankNimbostratus
    Mar 29, 2011
    Nicely done. If you've not gone through it up until now, you may want to go through the typefactory screencast that I did a while back to help get folks up to speed on how pycontrol/suds handles types. You've discovered, as have a couple of other folks, that Suds will take a normal python data structure and try to do the right thing with it. IIRC, this isn't completely consistent though, especially with nested types. So I always use the typefactory, which is much more explicit...

     

     

    Anyhow, here's an example that may be useful for you (done via an iPython interactive shell session). It may save you a few lines of code.

     

    In [18]: r.create.params
Out[18]: [(rules, u'LocalLB.Rule.RuleDefinitionSequence')]  This is the data structure we need to pass into the create call. Let's create the LocalLB.RuleDefinition object...
In [19]: r_def = r.typefactory.create('LocalLB.Rule.RuleDefinition')
In [20]: print r_def
(LocalLB.Rule.RuleDefinition){
   rule_name = None
   rule_definition = None
 }  This shows us what attributes we need to tickle to pass in the call. Let's do that now...
In [21]: r_def.rule_name = 'YOYO_pyControl'  The name of the rule. Now we'll actually add the iRule code.
In [22]: raw_code = '''
   ....: when HTTP_REQUEST {
   ....:        log local0. "Python - I can fly!!"
   ....: }'''  Now we'll add this to our object's rule_definition attribute...
In [23]: r_def.rule_definition = raw_code  Now we'll add it to BigIP...
In [24]: r.create(rules = [r_def])  Notice to create a 'sequence' I just treat it like a list. Let's see if it saved!
In [25]: r.get_list()
Out[25]:
[ _sys_APM_activesync,
 _sys_auth_ssl_cc_ldap,
 _sys_auth_krbdelegate,
 _sys_https_redirect, YOYO_pyControl,
 _sys_auth_ssl_crldp,
 _sys_auth_ssl_ocsp,
 nextgen-test,
 connection-limit,
 nextgen-dg-acl]
    Thanks for the post and I look forward to hearing more about your project!

     

    -Matt Cauthorn