Add filter to turn a string into a UUID

This filter was made because I needed to create idempotent UUIDs when
installing the agent for Go (http://go.cd), which uses UUIds to
distinguish the agents from each other.

It uses a newly created Ansible namespace to distinguish UUIDs created
by Ansible from any other source. The new namespace is a random one
created by uuidgen on OSX.

lib/ansible/runner/filter_plugins/core.py

@@ -29,6 +29,7 @@ import hashlib
 import string
 import operator as py_operator
 from random import SystemRandom, shuffle
+import uuid
 
 import yaml
 from jinja2.filters import environmentfilter
@@ -38,6 +39,9 @@ from ansible import errors
 from ansible.utils import md5s, checksum_s
 
 
+UUID_NAMESPACE_ANSIBLE = uuid.UUID('361E6D51-FAEC-444A-9079-341386DA8E2E')
+
+
 def to_nice_yaml(*a, **kw):
     '''Make verbose, human readable yaml'''
     return yaml.safe_dump(*a, indent=4, allow_unicode=True, default_flow_style=False, **kw)
@@ -297,6 +301,8 @@ def get_encrypted_password(password, hashtype='sha512', salt=None):
 
     return None
 
+def to_uuid(string):
+    return str(uuid.uuid5(UUID_NAMESPACE_ANSIBLE, str(string)))
 
 class FilterModule(object):
     ''' Ansible core jinja2 filters '''
@@ -307,6 +313,9 @@ class FilterModule(object):
             'b64decode': base64.b64decode,
             'b64encode': base64.b64encode,
 
+            # uuid
+            'to_uuid': to_uuid,
+
             # json
             'to_json': to_json,
             'to_nice_json': to_nice_json,