Genericize module to support multiple distros

Make the module implementatino more generic to support distributions
other than Ubuntu in the future.

Adds distro as a new parameter.

library/cloud/ec2_ami_search

@@ -18,16 +18,18 @@
 # along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
 DOCUMENTATION = '''
 ---
-module: ec2_ubuntu_ami
-short_description: Retrieve AWS AMIs for official Ubuntu images
+module: ec2_ami_search
+short_description: Retrieve AWS AMI for a given operating system.
 description:
-  - The Ubuntu project maintains a list of the latest version of Ubuntu images on EC2 accessible via http.
-  - This module retrieves the AMI for a given Ubuntu release by making an http query against the appropriate cloud-images.ubuntu.com url and parsing the output.
-  - For example: https://cloud-images.ubuntu.com/query/precise/server/released.current.txt has information about Ubuntu 12.04 (precise pangolin) release, server edition.
+  - Look up the most recent AMI on AWS for a given operating system.
   - Returns C(ami), C(aki), C(ari), C(serial), C(tag)
   - If there is no AKI or ARI associated with an image, these will be C(null).
   - Example output: C({"ami": "ami-69f5a900", "changed": false, "aki": "aki-88aa75e1", "tag": "release", "ari": null, "serial": "20131024"})
 options:
+  distro:
+    description: Linux distribution (e.g., C(ubuntu))
+    required: true
+    choices: ["ubuntu"]
   release:
     description: short name of the release (e.g., C(precise))
     required: true
@@ -67,7 +69,7 @@ EXAMPLES = '''
   connection: local
   tasks:
   - name: Get the Ubuntu precise AMI
-    ec2_ubuntu_ami: release=precise region=us-west-1 store=instance-store
+    ec2_ami_search: distro=ubuntu release=precise region=us-west-1 store=instance-store
     register: ubuntu_image
   - name: Start the EC2 instance
     ec2: image={{ ubuntu_image.ami }} instance_type=m1.small key_name=mykey
@@ -78,6 +80,8 @@ import json
 import urllib2
 import urlparse
 
+SUPPORTED_DISTROS = ['ubuntu']
+
 AWS_REGIONS = ['ap-northeast-1',
                'ap-southeast-1',
                'ap-southeast-2',
@@ -98,9 +102,31 @@ def get_url(module, url):
     return r
 
 
-def get_ami(table, release, stream, store,
-            arch, region, virt):
-    """ Get the Ubuntu AMI that matches query given a table of AMIs
+def ubuntu(module):
+    """ Get the ami for ubuntu """
+
+    release = module.params['release']
+    stream = module.params['stream']
+    store = module.params['store']
+    arch = module.params['arch']
+    region = module.params['region']
+    virt = module.params['virt']
+
+    url = get_ubuntu_url(release, stream)
+
+    req = get_url(module, url)
+    reader = csv.reader(req, delimiter='\t')
+    try:
+        ami, aki, ari, tag, serial = lookup_ubuntu_ami(reader, release, stream,
+            store, arch, region, virt)
+        module.exit_json(changed=False, ami=ami, aki=aki, ari=ari, tag=tag,
+            serial=serial)
+    except KeyError:
+        module.fail_json(msg="No matching AMI found")
+
+
+def lookup_ubuntu_ami(table, release, stream, store, arch, region, virt):
+    """ Look up the Ubuntu AMI that matches query given a table of AMIs
 
         table: an iterable that returns a row of
                (release, stream, tag, serial, region, ami, aki, ari, virt)
@@ -138,6 +164,7 @@ def get_ubuntu_url(release, stream):
 
 def main():
     arg_spec = dict(
+        distro=dict(required=True, choices=SUPPORTED_DISTROS),
         release=dict(required=True),
         stream=dict(required=False, default='server',
             choices=['desktop', 'server']),
@@ -150,24 +177,13 @@ def main():
             choices=['paravirtual', 'hvm'])
     )
     module = AnsibleModule(argument_spec=arg_spec)
-    release = module.params['release']
-    stream = module.params['stream']
-    store = module.params['store']
-    arch = module.params['arch']
-    region = module.params['region']
-    virt = module.params['virt']
+    distro = module.params['distro']
 
-    url = get_ubuntu_url(release, stream)
+    if distro == 'ubuntu':
+        ubuntu(module)
+    else:
+        module.fail_json(msg="Unsupported distro: %s" % distro)
 
-    req = get_url(module, url)
-    reader = csv.reader(req, delimiter='\t')
-    try:
-        ami, aki, ari, tag, serial = get_ami(reader, release, stream, store,
-          arch, region, virt)
-        module.exit_json(changed=False, ami=ami, aki=aki, ari=ari, tag=tag,
-            serial=serial)
-    except KeyError:
-        module.fail_json(msg="No matching AMI found")
 
 
 # this is magic, see lib/ansible/module_common.py