Specify nova image and flavor by name

Putting uuid and numberic identifies in playbooks is fragile, especially
with cloud providers who change them out from under you. Asking for
Ubuntu 14.04 is consistent, the UUID associated with that is not. Add
mutually exclusive parameters to allow for specifying images by name and
flavors by RAM amount.

library/cloud/nova_compute

@@ -73,12 +73,22 @@ options:
      default: None
    image_id:
      description:
-        - The id of the image that has to be cloned
+        - The id of the base image to boot. Mutually exclusive with image_name
+     required: true
+     default: None
+   image_name:
+     description:
+        - The name of the base image to boot. Mutually exclusive with image_id
      required: true
      default: None
    flavor_id:
      description:
-        - The id of the flavor in which the new VM has to be created
+        - The id of the flavor in which the new VM has to be created. Mutually exclusive with flavor_ram
+     required: false
+     default: 1
+   flavor_ram:
+     description:
+        - The minimum amount of ram in MB that the flavor in which the new VM has to be created must have. Mutually exclusive with flavor_id
      required: false
      default: 1
    key_name:
@@ -323,8 +333,35 @@ def _get_ips(addresses, ext_tag, key_name):
     return ret
 
 
+def _get_image_id(module, nova):
+    if module.params['image_name']:
+        image = None
+        for img in nova.images.list():
+            if img.name == module.params['image_name']:
+                image = img
+                break
+            if img.name.startswith(module.params['image_name']) and '(deprecated)' not in img.name:
+                image = img
+        if not image:
+            module.fail_json(msg = "Error finding image id from name(%s)" % module.params['image_name'])
+        return image.id
+    return module.params['image_id']
+
+
+def _get_flavor_id(module, nova):
+    if module.params['flavor_ram']:
+        try:
+            flavor = nova.flavors.find(ram=module.params['flavor_ram'])
+        except exceptions.NotFound as e:
+            module.fail_json(msg = "Error finding flavor with %sMB of RAM" % module.params['flavor_ram'])
+        return flavor.id
+    return module.params['flavor_id']
+
+
 def _create_server(module, nova):
-    bootargs = [module.params['name'], module.params['image_id'], module.params['flavor_id']]
+    image_id = _get_image_id(module, nova)
+    flavor_id = _get_flavor_id(module, nova)
+    bootargs = [module.params['name'], image_id, flavor_id]
     bootkwargs = {
                 'nics' : module.params['nics'],
                 'meta' : module.params['meta'],
@@ -402,7 +439,9 @@ def main():
     argument_spec.update(dict(
         name                            = dict(required=True),
         image_id                        = dict(default=None),
+        image_name                      = dict(default=None),
         flavor_id                       = dict(default=1),
+        flavor_ram                      = dict(default=None, type='int'),
         key_name                        = dict(default=None),
         security_groups                 = dict(default='default'),
         nics                            = dict(default=None),
@@ -421,6 +460,8 @@ def main():
             ['auto_floating_ip','floating_ips'],
             ['auto_floating_ip','floating_ip_pools'],
             ['floating_ips','floating_ip_pools'],
+            ['image_id','image_name'],
+            ['flavor_id','flavor_ram'],
         ],
     )
 
@@ -438,8 +479,8 @@ def main():
         module.fail_json(msg = "Unable to authorize user: %s" % e.message)
 
     if module.params['state'] == 'present':
-        if not module.params['image_id']:
+        if not module.params['image_id'] and not module.params['image_name']:
-            module.fail_json( msg = "Parameter 'image_id' is required if state == 'present'")
+            module.fail_json( msg = "Parameter 'image_id' or `image_name` is required if state == 'present'")
         else:
             _get_server_state(module, nova)
             _create_server(module, nova)