Rebase attempt

No idea if I'm rebasing properly or not.  This is my first attempt.

library/cloud/ec2_ami

@@ -23,22 +23,22 @@ description:
 options:
   ec2_url:
     description:
-      - url to use to connect to EC2 or your Eucalyptus cloud (by default the module will use EC2 endpoints)
+      - Url to use to connect to EC2 or your Eucalyptus cloud (by default the module will use EC2 endpoints).  Must be specified if region is not used. If not set then the value of the EC2_URL environment variable, if any, is used
     required: false
     default: null
     aliases: []
-  ec2_secret_key:
+  aws_secret_key:
     description:
-      - ec2 secret key
+      - AWS secret key. If not set then the value of the AWS_SECRET_KEY environment variable is used. 
     required: false
     default: null
-    aliases: []
-  ec2_access_key:
+    aliases: [ 'ec2_secret_key', 'secret_key' ]
+  aws_access_key:
     description:
-      - ec2 access key
+      - AWS access key. If not set then the value of the AWS_ACCESS_KEY environment variable is used.
     required: false
     default: null
-    aliases: []
+    aliases: ['ec2_access_key', 'access_key' ]
   instance_id:
     description:
       - instance id of the image to create
@@ -71,10 +71,10 @@ options:
     aliases: []
   region:
     description:
-      - the EC2 region to use
+      - The AWS region to use.  Must be specified if ec2_url is not used. If not specified then the value of the EC2_REGION environment variable, if any, is used.
     required: false
     default: null
-    aliases: []
+    aliases: [ 'aws_region', 'ec2_region' ]
   description:
     description:
       - An optional human-readable string describing the contents and purpose of the AMI.
@@ -113,8 +113,8 @@ EXAMPLES = '''
 # Basic AMI Creation
 - local_action:
     module: ec2_ami
-    ec2_access_key: xxxxxxxxxxxxxxxxxxxxxxx
-    ec2_secret_key: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+    aws_access_key: xxxxxxxxxxxxxxxxxxxxxxx
+    aws_secret_key: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
     instance_id: i-xxxxxx
     wait: yes
     name: newtest
@@ -123,8 +123,9 @@ EXAMPLES = '''
 # Basic AMI Creation, without waiting
 - local_action:
     module: ec2_ami
-    ec2_access_key: xxxxxxxxxxxxxxxxxxxxxxx
-    ec2_secret_key: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+    aws_access_key: xxxxxxxxxxxxxxxxxxxxxxx
+    aws_secret_key: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+    region: xxxxxx
     instance_id: i-xxxxxx
     wait: no
     name: newtest
@@ -133,8 +134,9 @@ EXAMPLES = '''
 # Deregister/Delete AMI
 - local_action:
     module: ec2_ami
-    ec2_access_key: xxxxxxxxxxxxxxxxxxxxxxx
-    ec2_secret_key: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+    aws_access_key: xxxxxxxxxxxxxxxxxxxxxxx
+    aws_secret_key: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+    region: xxxxxx
     image_id: ${instance.image_id}
     delete_snapshot: True
     state: absent
@@ -142,8 +144,9 @@ EXAMPLES = '''
 # Deregister AMI
 - local_action:
     module: ec2_ami
-    ec2_access_key: xxxxxxxxxxxxxxxxxxxxxxx
-    ec2_secret_key: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+    aws_access_key: xxxxxxxxxxxxxxxxxxxxxxx
+    aws_secret_key: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+    region: xxxxxx
     image_id: ${instance.image_id}
     delete_snapshot: False
     state: absent
@@ -152,6 +155,15 @@ EXAMPLES = '''
 import sys
 import time
 
+AWS_REGIONS = ['ap-northeast-1',
+               'ap-southeast-1',
+               'ap-southeast-2',
+               'eu-west-1',
+               'sa-east-1',
+               'us-east-1',
+               'us-west-1',
+               'us-west-2']
+
 try:
     import boto.ec2
 except ImportError:
@@ -235,9 +247,9 @@ def deregister_image(module, ec2):
 def main():
     module = AnsibleModule(
         argument_spec = dict(
-            ec2_url = dict(aliases=['EC2_URL']),
-            ec2_secret_key = dict(aliases=['EC2_SECRET_KEY'], no_log=True),
-            ec2_access_key = dict(aliases=['EC2_ACCESS_KEY']),
+            ec2_url = dict(),
+            aws_secret_key = dict(aliases=['ec2_secret_key', 'secret_key'], no_log=True),
+            aws_access_key = dict(aliases=['ec2_access_key', 'access_key']),
             instance_id = dict(),
             image_id = dict(),
             delete_snapshot = dict(),
@@ -247,38 +259,51 @@ def main():
             description = dict(default=""),
             no_reboot = dict(default=True, type="bool"),
             state = dict(default='present'),
-            region = dict()
+            region = dict(aliases=['aws_region', 'ec2_region'], choices=AWS_REGIONS)
         )
     )
 
     ec2_url = module.params.get('ec2_url')
-    ec2_secret_key = module.params.get('ec2_secret_key')
-    ec2_access_key = module.params.get('ec2_access_key')
+    aws_secret_key = module.params.get('aws_secret_key')
+    aws_access_key = module.params.get('aws_access_key')
     region = module.params.get('region')
 
     # allow eucarc environment variables to be used if ansible vars aren't set
     if not ec2_url and 'EC2_URL' in os.environ:
         ec2_url = os.environ['EC2_URL']
-    if not ec2_secret_key and 'EC2_SECRET_KEY' in os.environ:
-        ec2_secret_key = os.environ['EC2_SECRET_KEY']
-    if not ec2_access_key and 'EC2_ACCESS_KEY' in os.environ:
-        ec2_access_key = os.environ['EC2_ACCESS_KEY']
+
+    if not aws_secret_key:
+        if  'AWS_SECRET_KEY' in os.environ:
+            aws_secret_key = os.environ['AWS_SECRET_KEY']
+        elif 'EC2_SECRET_KEY' in os.environ:
+            aws_secret_key = os.environ['EC2_SECRET_KEY']
+
+    if not aws_access_key:
+        if 'AWS_ACCESS_KEY' in os.environ:
+            aws_access_key = os.environ['AWS_ACCESS_KEY']
+        elif 'EC2_ACCESS_KEY' in os.environ:
+            aws_access_key = os.environ['EC2_ACCESS_KEY']
+
+    if not region:
+        if 'AWS_REGION' in os.environ:
+            region = os.environ['AWS_REGION']
+        elif 'EC2_REGION' in os.environ:
+            region = os.environ['EC2_REGION']
 
     # If we have a region specified, connect to its endpoint.
     if region:
         try:
-            ec2 = boto.ec2.connect_to_region(region, aws_access_key_id=ec2_access_key, aws_secret_access_key=ec2_secret_key)
-        except boto.exception.NoAuthHandlerFound, e:
-            module.fail_json(msg = str(" %s %s %s " % (region, ec2_access_key, ec2_secret_key)))
-    # Otherwise, no region so we fallback to the old connection method
-    else:
-        try:
-            if ec2_url: # if we have an URL set, connect to the specified endpoint
-                ec2 = boto.connect_ec2_endpoint(ec2_url, ec2_access_key, ec2_secret_key)
-            else: # otherwise it's Amazon.
-                ec2 = boto.connect_ec2(ec2_access_key, ec2_secret_key)
+            ec2 = boto.ec2.connect_to_region(region, aws_access_key_id=aws_access_key, aws_secret_access_key=aws_secret_key)
         except boto.exception.NoAuthHandlerFound, e:
             module.fail_json(msg = str(e))
+    # If we specified an ec2_url then try connecting to it
+    elif ec2_url:
+        try:
+            ec2 = boto.connect_ec2_endpoint(ec2_url, aws_access_key, aws_secret_key)
+        except boto.exception.NoAuthHandlerFound, e:
+            module.fail_json(msg = str(e))
+    else:
+        module.fail_json(msg="Either region or ec2_url must be specified")
 
     if module.params.get('state') == 'absent':
         if not module.params.get('image_id'):