- The trick couldn't take more than an hour to actually implement
- The trick had to demonstrate some unexpected capability of the system
- The trick had to at least point in the direction of some actually useful capability, even though the trick in it's current form may not have been tremendously useful
The inspiration behind this Stupid Boto Trick was a thread on the SimpleDB forum. A user asked whether it was possible to get a listing of all SimpleDB domains across all AWS regions. The answer is "no" or at least "no, not directly". Each region has it's own set of service endpoints and you have to connect to a specific endpoint to issue requests. So, you would have to ask each SimpleDB endpoint for a list of domains and then combine the two lists on the client side.
To address this, I created a new Python class called a ServiceSet. A ServiceSet represents all of the endpoints for a particular Service and, when you access a particular attribute or method on the ServerSet, it actually performs the action on each of the endpoints of the service and then assembles the results for you. Here's the quick, dirty, undocumented code. Hey, like I said, I only get an hour at the most!
class ServiceSet(list):
def __init__(self, service, **kwargs):
self.service = service
self.regions = None
if self.service == 'ec2':
import boto.ec2
self.regions = boto.ec2.regions(**kwargs)
elif self.service == 'sdb':
import boto.sdb
self.regions = boto.sdb.regions(**kwargs)
elif self.service == 'sqs':
import boto.sqs
self.regions = boto.sqs.regions(**kwargs)
for region in self.regions:
self.append(region.connect(**kwargs))
def __getattr__(self, name):
results = []
is_callable = False
for conn in self:
try:
val = getattr(conn, name)
if callable(val):
is_callable = True
results.append(val)
except:
results.append(None)
if is_callable:
self.map_list = results
return self.map
return results
def map(self, *args):
results = []
for fn in self.map_list:
results.append(fn(*args))
return results
>>> from serverset import ServerSet
>>> s = ServerSet('sdb')
>>> s
[SDBConnection:sdb.amazonaws.com, SDBConnection:sdb.eu-west-1.amazonaws.com]
>>>
s that contains connections to both endpoints for the SimpleDB service. Let's get a list of all of our domains, across both regions:
>>> s.get_all_domains()
[[Domain:foo,
Domain:test1248881005],
[Domain:bar]]
>>>
In addition to listing domains, you can also do other things. In fact, any method available on an SDBConnection object can also be invoked on the ServerSet which will, in turn, invoke the appropriate method on each of it's connections. Here's a transcript showing a bit of playing around with the ServerSet object:
>>> s.create_domain('serverset')
[Domain:serverset, Domain:serverset]
>>> s.put_attributes('serverset', 'testitem', {'foo' : 'bar', 'fie' : 'baz'})
[True, True]
>>> s.select('serverset', 'select * from serverset')
[[{u'fie': u'baz', u'foo': u'bar'}], [{u'fie': u'baz', u'foo': u'bar'}]]
>>> s.delete_domain('serverset')
[True, True]
So, there we have it. The first Stupid Boto Trick. I've created a Mercurial repo on bitbucket.org just to collect these tricks. You can access it at http://bitbucket.org/mitch/stupidbototricks/. You also need to be running at least r1306 of boto.
