Retry EC2 run_instances on "Invalid IAM Instance Profile name" errors

Instance creation could fail with an error like this if the IAM instance
profile for the instance was created a short time before run_instances,
and had not yet propagated (which happened nearly every time on fast
networks):

    "Instance creation failed => InvalidParameterValue: Value
    (xxx_profile) for parameter iamInstanceProfile.name is invalid.
    Invalid IAM Instance Profile name"

We modify ec2.py to use an "EC2Retry" wrapper that inherits from
CloudRetry and wraps run_instances, detects the InvalidParameterValue
exception with the 'iamInstanceProfile.name is invalid' message, and
retries that request a few times.

Incidentally, terraform has the same problem and used the same fix,
right up to using string matching on the error message to figure out
whether it's the right error or not:

hashicorp/terraform-provider-aws#3055

lib/ansible/modules/cloud/amazon/ec2.py

@@ -576,6 +576,7 @@
 from ansible.module_utils.ec2 import get_aws_connection_info, ec2_argument_spec, ec2_connect
 from ansible.module_utils.six import get_function_code, string_types
 from ansible.module_utils._text import to_bytes, to_text
+from ansible.module_utils.cloud import CloudRetry
 
 try:
     import boto.ec2
@@ -588,6 +589,20 @@
     HAS_BOTO = False
 
 
+class EC2Retry(CloudRetry):
+    base_class = boto.exception.BotoServerError
+
+    @staticmethod
+    def status_code_from_exception(e):
+        return [e.error_code, e.error_message]
+
+    @staticmethod
+    def found(rc, catch_extra_error_codes=None):
+        if rc[0] == 'InvalidParameterValue' and 'iamInstanceProfile.name is invalid' in rc[1]:
+            return True
+
+        return False
+
 def find_running_instances_by_count_tag(module, ec2, vpc, count_tag, zone=None):
 
     # get reservations for instances that match tag(s) and are in the desired state
@@ -959,6 +974,9 @@ def enforce_count(module, ec2, vpc):
 
     return (all_instances, instance_dict_array, changed_instance_ids, changed)
 
+@EC2Retry.backoff(tries=3, delay=5, backoff=2.0)
+def run_instances(ec2, **params):
+    return ec2.run_instances(**params)
 
 def create_instances(module, ec2, vpc, override_count=None):
     """
@@ -1165,7 +1183,7 @@ def create_instances(module, ec2, vpc, override_count=None):
                 params['instance_initiated_shutdown_behavior'] = instance_initiated_shutdown_behavior or 'stop'
 
                 try:
-                    res = ec2.run_instances(**params)
+                    res = run_instances(ec2, **params)
                 except boto.exception.EC2ResponseError as e:
                     if (params['instance_initiated_shutdown_behavior'] != 'terminate' and
                             "InvalidParameterCombination" == e.error_code):