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# Copyright 2012-2015, Inc. or its affiliates. All Rights Reserved.
# Licensed under the Apache License, Version 2.0 (the "License"). You
# may not use this file except in compliance with the License. A copy of
# the License is located at
# or in the "license" file accompanying this file. This file is
# ANY KIND, either express or implied. See the License for the specific
# language governing permissions and limitations under the License.
import sys
import time
import logging
import botocore
import collections
from awscli.customizations.cloudformation import exceptions
from awscli.customizations.cloudformation.artifact_exporter import mktempfile, parse_s3_url
from datetime import datetime
LOG = logging.getLogger(__name__)
ChangeSetResult = collections.namedtuple(
"ChangeSetResult", ["changeset_id", "changeset_type"])
class Deployer(object):
def __init__(self, cloudformation_client,
self._client = cloudformation_client
self.changeset_prefix = changeset_prefix
def has_stack(self, stack_name):
Checks if a CloudFormation stack with given name exists
:param stack_name: Name or ID of the stack
:return: True if stack exists. False otherwise
resp = self._client.describe_stacks(StackName=stack_name)
if len(resp["Stacks"]) != 1:
return False
# When you run CreateChangeSet on a a stack that does not exist,
# CloudFormation will create a stack and set it's status
# REVIEW_IN_PROGRESS. However this stack is cannot be manipulated
# by "update" commands. Under this circumstances, we treat like
# this stack does not exist and call CreateChangeSet will
# ChangeSetType set to CREATE and not UPDATE.
stack = resp["Stacks"][0]
return stack["StackStatus"] != "REVIEW_IN_PROGRESS"
except botocore.exceptions.ClientError as e:
# If a stack does not exist, describe_stacks will throw an
# exception. Unfortunately we don't have a better way than parsing
# the exception msg to understand the nature of this exception.
msg = str(e)
if "Stack with id {0} does not exist".format(stack_name) in msg:
LOG.debug("Stack with id {0} does not exist".format(
return False
# We don't know anything about this exception. Don't handle
LOG.debug("Unable to get stack details.", exc_info=e)
raise e
def create_changeset(self, stack_name, cfn_template,
parameter_values, capabilities, role_arn,
notification_arns, s3_uploader, tags):
Call Cloudformation to create a changeset and wait for it to complete
:param stack_name: Name or ID of stack
:param cfn_template: CloudFormation template string
:param parameter_values: Template parameters object
:param capabilities: Array of capabilities passed to CloudFormation
:param tags: Array of tags passed to CloudFormation
now = datetime.utcnow().isoformat()
description = "Created by AWS CLI at {0} UTC".format(now)
# Each changeset will get a unique name based on time
changeset_name = self.changeset_prefix + str(int(time.time()))
if not self.has_stack(stack_name):
changeset_type = "CREATE"
# When creating a new stack, UsePreviousValue=True is invalid.
# For such parameters, users should either override with new value,
# or set a Default value in template to successfully create a stack.
parameter_values = [x for x in parameter_values
if not x.get("UsePreviousValue", False)]
changeset_type = "UPDATE"
# UsePreviousValue not valid if parameter is new
summary = self._client.get_template_summary(StackName=stack_name)
existing_parameters = [parameter['ParameterKey'] for parameter in \
parameter_values = [x for x in parameter_values
if not (x.get("UsePreviousValue", False) and \
x["ParameterKey"] not in existing_parameters)]
kwargs = {
'ChangeSetName': changeset_name,
'StackName': stack_name,
'TemplateBody': cfn_template,
'ChangeSetType': changeset_type,
'Parameters': parameter_values,
'Capabilities': capabilities,
'Description': description,
'Tags': tags,
# If an S3 uploader is available, use TemplateURL to deploy rather than
# TemplateBody. This is required for large templates.
if s3_uploader:
with mktempfile() as temporary_file:
url = s3_uploader.upload_with_dedup(, "template")
# TemplateUrl property requires S3 URL to be in path-style format
parts = parse_s3_url(url, version_property="Version")
kwargs['TemplateURL'] = s3_uploader.to_path_style_s3_url(parts["Key"], parts.get("Version", None))
# don't set these arguments if not specified to use existing values
if role_arn is not None:
kwargs['RoleARN'] = role_arn
if notification_arns is not None:
kwargs['NotificationARNs'] = notification_arns
resp = self._client.create_change_set(**kwargs)
return ChangeSetResult(resp["Id"], changeset_type)
except Exception as ex:
LOG.debug("Unable to create changeset", exc_info=ex)
raise ex
def wait_for_changeset(self, changeset_id, stack_name):
Waits until the changeset creation completes
:param changeset_id: ID or name of the changeset
:param stack_name: Stack name
:return: Latest status of the create-change-set operation
sys.stdout.write("\nWaiting for changeset to be created..\n")
# Wait for changeset to be created
waiter = self._client.get_waiter("change_set_create_complete")
# Poll every 5 seconds. Changeset creation should be fast
waiter_config = {'Delay': 5}
waiter.wait(ChangeSetName=changeset_id, StackName=stack_name,
except botocore.exceptions.WaiterError as ex:
LOG.debug("Create changeset waiter exception", exc_info=ex)
resp = ex.last_response
status = resp["Status"]
reason = resp["StatusReason"]
if status == "FAILED" and \
"The submitted information didn't contain changes." in reason or \
"No updates are to be performed" in reason:
raise exceptions.ChangeEmptyError(stack_name=stack_name)
raise RuntimeError("Failed to create the changeset: {0} "
"Status: {1}. Reason: {2}"
.format(ex, status, reason))
def execute_changeset(self, changeset_id, stack_name):
Calls CloudFormation to execute changeset
:param changeset_id: ID of the changeset
:param stack_name: Name or ID of the stack
:return: Response from execute-change-set call
return self._client.execute_change_set(
def wait_for_execute(self, stack_name, changeset_type):
sys.stdout.write("Waiting for stack create/update to complete\n")
# Pick the right waiter
if changeset_type == "CREATE":
waiter = self._client.get_waiter("stack_create_complete")
elif changeset_type == "UPDATE":
waiter = self._client.get_waiter("stack_update_complete")
raise RuntimeError("Invalid changeset type {0}"
# Poll every 5 seconds. Optimizing for the case when the stack has only
# minimal changes, such the Code for Lambda Function
waiter_config = {
'Delay': 5,
'MaxAttempts': 720,
waiter.wait(StackName=stack_name, WaiterConfig=waiter_config)
except botocore.exceptions.WaiterError as ex:
LOG.debug("Execute changeset waiter exception", exc_info=ex)
raise exceptions.DeployFailedError(stack_name=stack_name)
def create_and_wait_for_changeset(self, stack_name, cfn_template,
parameter_values, capabilities, role_arn,
notification_arns, s3_uploader, tags):
result = self.create_changeset(
stack_name, cfn_template, parameter_values, capabilities,
role_arn, notification_arns, s3_uploader, tags)
self.wait_for_changeset(result.changeset_id, stack_name)
return result
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