def determine_changed_bucket_policy()

in social-media/create-aml-model.py [0:0]

• 22 lines of code
• 12 McCabe index (conditional complexity)

def determine_changed_bucket_policy(existing_bucket_policy, target_bucket_policy):
    if existing_bucket_policy == '':
        return target_bucket_policy
    json_policy = json.loads(existing_bucket_policy)
    target_statement = json.loads(target_bucket_policy)['Statement'][0]
    target_resource_arn = target_statement['Resource'][0]
    for statement in json_policy['Statement']:
        if (
            statement.has_key('Principal') and
            statement['Principal'].has_key('Service') and
            statement['Principal']['Service'] == 'machinelearning.amazonaws.com' and
            statement['Effect'] == "Allow" and
            "s3:GetObject" in statement['Action']
        ):
            if target_resource_arn == statement['Resource'] or target_resource_arn in statement['Resource']:
                # no change required
                return None
            elif isinstance(statement['Resource'], str) or isinstance(statement['Resource'], unicode):
                # convert the resource value to a list
                statement['Resource'] = [statement['Resource']]
            # If we reach here then we know that resource is a list that doesn't contain target_resource_arn
            statement['Resource'].append(target_resource_arn)
            return json.dumps(json_policy)
    # If we reach here then we know that simplest change is to append the desired statement into the policy.
    json_policy['Statement'].append(target_statement)
    return json.dumps(json_policy)