early version works for create, not idempotent

playbooks/library/ec2_subnet

+#!/usr/bin/env python
+# This file is part of Ansible
+#
+# Ansible is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Ansible is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
+
+DOCUMENTATION = """
+---
+module: ec2_subnet
+short_description: Create or delete AWS Subnets
+description:
+  - Can create or delete AwS Subnets
+version_added: "1.8"
+author: Edward Zarecor
+options:
+  state:
+    description:
+      - create, update or delete the subnet
+    required: true
+    choices: ['present', 'absent']
+  name:
+    description:
+      - Unique name for subnet
+    required: true
+  cidr_block:
+    description:
+      - The cidr block of the subnet
+    aliases: ['cidr']
+  availability_zone
+    description:
+      - The availability zone of the subnet
+    aliases: ['az']
+  vpc_id:
+    description:
+      - The VPC that this acl belongs to
+    required: true
+    default: null
+extends_documentation_fragment: aws
+"""
+
+EXAMPLES = '''
+'''
+
+from ansible.module_utils.basic import *
+from ansible.module_utils.ec2 import *
+import sys
+try:
+    import boto.vpc
+except ImportError:
+    print "failed=True msg='boto required for this module'"
+    sys.exit(1)
+
+from boto.exception import NoAuthHandlerFound
+
+
+class NonUniqueSubnetSpecification(Exception):
+    pass
+
+
+class SubnetManager:
+
+    def __init__(self, connection, vpc_id, cidr_block, az, name, route_table_id, tags=[]):
+
+        self.connection = connection
+        self.vpc_id = vpc_id
+        self.cidr_block = cidr_block
+        self.az = az
+        self.name = name
+        self.route_table_id = route_table_id
+        self.tags = tags
+        self.subnet = None
+
+    def get_subnet(self):
+
+        if not self.subnet:
+
+            subnets = self.connection. \
+                get_all_subnets(filters={"vpc_id": self.vpc_id,
+                                         "cidr_block": self.cidr_block,
+                                         "availability_zone": self.az})
+            if len(subnets) > 1:
+                message = "Subnet specifier of vpc_id {vpc_id}, cidr_block {cidr_block} " \
+                          "and az {az}, return more than one result".format(
+                    vpc_id=self.vpc_id, cidr_block=self.cidr_block,az=self.az)
+                raise NonUniqueSubnetSpecification(message)
+            elif len(subnets) == 1:
+                self.subnet = subnets[0]
+
+        return self.subnet
+
+    def present(self):
+
+        if self.get_subnet():
+            changed = self.update_subnet()
+        else:
+            changed = self.create_subnet()
+
+        results = dict(changed=changed,
+                       subnet_id=self.subnet.id,
+                       subnet_name=self.name,
+                       vpc_id=self.vpc_id)
+
+        return results
+
+    def create_subnet(self):
+        changed = True
+        self.subnet = self.connection.create_subnet(self.vpc_id, self.cidr_block, availability_zone=self.az)
+        self.do_tags()
+        self.connection.associate_route_table(self.route_table_id, self.subnet.id)
+        return changed
+
+    def update_subnet(self):
+        changed = False
+        self.do_tags()
+
+        results = self.connection.get_all_route_tables(
+                    filters={'association.subnet_id': self.subnet.id, 'vpc_id': self.vpc_id})
+
+        if len(results) == 1:
+            route_table = results[0]
+            assoc = self.get_association_from_route_table(route_table, self.subnet)
+            if assoc.route_table_id != self.route_table_id:
+                self.connection.replace_route_table_association_with_assoc(assoc.id, self.route_table_id)
+                changed = True
+        elif len(results) == 0:
+            # unlikely unless manual monkeying around
+            self.connection.associate_route_table(self.route_table_id, self.subnet.id)
+            changed == True
+
+        return changed
+
+    def absent(self):
+        changed = self.connection.delete_subnet(self.subnet.id)
+        return dict(changed=changed)
+
+    def get_association_from_route_table(self, route_table, subnet):
+        target = None
+        for assoc in route_table.associations:
+            if assoc.subnet_id == subnet.id:
+                target = assoc
+                break
+
+        return target
+
+    def do_tags(self):
+        """
+        Utility that creates all tags including the Name tag which is treated
+        as a first class params as a convenience.  Currently updates
+        existing tags, as the API overwrites them, but does not remove
+        orphans.
+        :return: None
+        """
+        tags = {'Name': self.name}
+        for tag in self.tags:
+            tags[tag['key']] = tag['value']
+
+        self.subnet.add_tags(tags)
+
+
+def main():
+    argument_spec = ec2_argument_spec()
+    argument_spec.update(
+        dict(
+            name=dict(required=True, type='str'),
+            state=dict(default='present', choices=['present', 'absent']),
+            vpc_id=dict(required=True, type='str'),
+            cidr_block=dict(required=True, type='str'),
+            az=dict(required=True, type='str'),
+            route_table_id=dict(require=True, type='str'),
+            tags=dict(type='list'),
+        )
+    )
+
+    module = AnsibleModule(argument_spec=argument_spec)
+    ec2_url, aws_access_key, aws_secret_key, region = get_ec2_creds(module)
+    profile = module.params.get('profile')
+    if region:
+        try:
+            connection = boto.vpc.connect_to_region(region, profile_name=profile)
+        except boto.exception.NoAuthHandlerFound, e:
+            module.fail_json(msg=str(e))
+    else:
+        module.fail_json(msg="region must be specified")
+
+    vpc_id = module.params.get('vpc_id')
+    cidr_block = module.params.get('cidr_block')
+    az = module.params.get('az')
+    name = module.params.get('name')
+    route_table_id = module.params.get('route_table_id')
+    tags = module.params.get('tags')
+
+    manager = SubnetManager(connection, vpc_id, cidr_block, az, name, route_table_id, tags)
+
+    state = module.params.get('state')
+
+    if state == 'present':
+        results = manager.present()
+    elif state == 'absent':
+        results = manager.absent()
+    else:
+        raise Exception("Unexpected value for state {0}".format(state))
+
+    module.exit_json(**results)
+
+main()