Add ability to retrieve error information from the WaiterError class

[jarruda]

When creating a CloudFormation stack that fails due to a resource already existing and rollback is enabled, the StackCreateComplete waiter throws an exception that it encountered a terminal failure state.

    boto3.set_stream_logger('boto3', level=boto3.logging.DEBUG)
    boto3.set_stream_logger('botocore', level=boto3.logging.DEBUG)
    boto3.set_stream_logger('boto3.resources', level=boto3.logging.DEBUG)

    cf = boto3.client('cloudformation')
    print("Creating stack...")
    cf.create_stack(StackName=STACKNAME, TemplateBody=TEMPLATE)
    print("Waiting for stack creation to complete...")
    cf.get_waiter('stack_create_complete').wait(StackName=STACKNAME)

Logging output:

2017-08-10 09:48:45,051 botocore.credentials [DEBUG] Looking for credentials via: env
2017-08-10 09:48:45,051 botocore.credentials [INFO] Found credentials in environment variables.
2017-08-10 09:48:45,052 botocore.loaders [DEBUG] Loading JSON file: /usr/local/lib/python2.7/dist-packages/botocore/data/endpoints.json
2017-08-10 09:48:45,069 botocore.loaders [DEBUG] Loading JSON file: /usr/local/lib/python2.7/dist-packages/botocore/data/cloudformation/2010-05-15/service-2.json
2017-08-10 09:48:45,080 botocore.loaders [DEBUG] Loading JSON file: /usr/local/lib/python2.7/dist-packages/botocore/data/_retry.json
2017-08-10 09:48:45,081 botocore.client [DEBUG] Registering retry handlers for service: cloudformation
2017-08-10 09:48:45,082 botocore.hooks [DEBUG] Event creating-client-class.cloudformation: calling handler <function add_generate_presigned_url at 0x7ff8793a57d0>
2017-08-10 09:48:45,083 botocore.args [DEBUG] The s3 config key is not a dictionary type, ignoring its value of: None
2017-08-10 09:48:45,084 botocore.endpoint [DEBUG] Setting cloudformation timeout as (60, 60)
Creating stack...
2017-08-10 09:48:45,085 botocore.hooks [DEBUG] Event before-parameter-build.cloudformation.CreateStack: calling handler <function generate_idempotent_uuid at 0x7ff879351e60>
2017-08-10 09:48:45,086 botocore.endpoint [DEBUG] Making request for OperationModel(name=CreateStack) (verify_ssl=True) with params: [redacted]
2017-08-10 09:48:45,087 botocore.hooks [DEBUG] Event request-created.cloudformation.CreateStack: calling handler <bound method RequestSigner.handler of <botocore.signers.RequestSigner object at 0x7ff878eeb390>>
2017-08-10 09:48:45,087 botocore.hooks [DEBUG] Event choose-signer.cloudformation.CreateStack: calling handler <function set_operation_specific_signer at 0x7ff879351d70>
2017-08-10 09:48:45,088 botocore.auth [DEBUG] Calculating signature using v4 auth.
2017-08-10 09:48:45,088 botocore.auth [DEBUG] CanonicalRequest:[redacted]
2017-08-10 09:48:45,090 botocore.auth [DEBUG] Signature:[redacted]
2017-08-10 09:48:45,094 botocore.endpoint [DEBUG] Sending http request: <PreparedRequest [POST]>
2017-08-10 09:48:45,095 botocore.vendored.requests.packages.urllib3.connectionpool [INFO] Starting new HTTPS connection (1): cloudformation.us-west-2.amazonaws.com
2017-08-10 09:48:45,455 botocore.vendored.requests.packages.urllib3.connectionpool [DEBUG] "POST / HTTP/1.1" 200 380
2017-08-10 09:48:45,455 botocore.parsers [DEBUG] Response headers: {'x-amzn-requestid': '[redacted]', 'date': 'Thu, 10 Aug 2017 16:48:45 GMT', 'content-length': '380', 'content-type': 'text/xml'}
2017-08-10 09:48:45,456 botocore.parsers [DEBUG] Response body:
<CreateStackResponse xmlns="http://cloudformation.amazonaws.com/doc/2010-05-15/">
  <CreateStackResult>
    <StackId>[redacted]</StackId>
  </CreateStackResult>
  <ResponseMetadata>
    <RequestId>[redacted]</RequestId>
  </ResponseMetadata>
</CreateStackResponse>

2017-08-10 09:48:45,457 botocore.hooks [DEBUG] Event needs-retry.cloudformation.CreateStack: calling handler <botocore.retryhandler.RetryHandler object at 0x7ff878f64cd0>
2017-08-10 09:48:45,457 botocore.retryhandler [DEBUG] No retry needed.
Waiting for stack creation to complete...
2017-08-10 09:48:45,465 botocore.loaders [DEBUG] Loading JSON file: /usr/local/lib/python2.7/dist-packages/botocore/data/cloudformation/2010-05-15/waiters-2.json
2017-08-10 09:48:45,466 botocore.hooks [DEBUG] Event before-parameter-build.cloudformation.DescribeStacks: calling handler <function generate_idempotent_uuid at 0x7ff879351e60>
2017-08-10 09:48:45,466 botocore.endpoint [DEBUG] Making request for OperationModel(name=DescribeStacks) (verify_ssl=True) with params: {'body': {'Action': u'DescribeStacks', 'StackName': '[redacted]', 'Version': u'2010-05-15'}, 'url': u'https://cloudformation.us-west-2.amazonaws.com/', 'headers': {'User-Agent': 'Boto3/1.4.5 Python/2.7.6 Linux/4.4.0-43-Microsoft Botocore/1.5.94'}, 'context': {'auth_type': None, 'client_region': 'us-west-2', 'has_streaming_input': False, 'client_config': <botocore.config.Config object at 0x7ff878eeb410>}, 'query_string': '', 'url_path': '/', 'method': u'POST'}
2017-08-10 09:48:45,466 botocore.hooks [DEBUG] Event request-created.cloudformation.DescribeStacks: calling handler <bound method RequestSigner.handler of <botocore.signers.RequestSigner object at 0x7ff878eeb390>>
2017-08-10 09:48:45,466 botocore.hooks [DEBUG] Event choose-signer.cloudformation.DescribeStacks: calling handler <function set_operation_specific_signer at 0x7ff879351d70>
2017-08-10 09:48:45,467 botocore.auth [DEBUG] Calculating signature using v4 auth.
2017-08-10 09:48:45,467 botocore.auth [DEBUG] CanonicalRequest:[redacted]
2017-08-10 09:48:45,468 botocore.auth [DEBUG] StringToSign:[redacted]
2017-08-10 09:48:45,533 botocore.parsers [DEBUG] Response body:
<DescribeStacksResponse xmlns="http://cloudformation.amazonaws.com/doc/2010-05-15/">
  <DescribeStacksResult>
    <Stacks>
      <member>
        <CreationTime>2017-08-10T16:48:45.324Z</CreationTime>
        <NotificationARNs/>
        <StackId>[redacted]</StackId>
        <StackName>[redacted]</StackName>
        <StackStatus>CREATE_IN_PROGRESS</StackStatus>
        <DisableRollback>false</DisableRollback>
        <Tags/>
        <StackStatusReason>User Initiated</StackStatusReason>
      </member>
    </Stacks>
  </DescribeStacksResult>
  <ResponseMetadata>
    <RequestId>[redacted]</RequestId>
  </ResponseMetadata>
</DescribeStacksResponse>

2017-08-10 09:48:45,535 botocore.hooks [DEBUG] Event needs-retry.cloudformation.DescribeStacks: calling handler <botocore.retryhandler.RetryHandler object at 0x7ff878f64cd0>
2017-08-10 09:48:45,535 botocore.retryhandler [DEBUG] No retry needed.
2017-08-10 09:49:15,536 botocore.hooks [DEBUG] Event before-parameter-build.cloudformation.DescribeStacks: calling handler <function generate_idempotent_uuid at 0x7ff879351e60>
2017-08-10 09:49:15,536 botocore.endpoint [DEBUG] Making request for OperationModel(name=DescribeStacks) (verify_ssl=True) with params: [redacted]
2017-08-10 09:49:15,537 botocore.hooks [DEBUG] Event request-created.cloudformation.DescribeStacks: calling handler <bound method RequestSigner.handler of <botocore.signers.RequestSigner object at 0x7ff878eeb390>>
2017-08-10 09:49:15,537 botocore.hooks [DEBUG] Event choose-signer.cloudformation.DescribeStacks: calling handler <function set_operation_specific_signer at 0x7ff879351d70>
2017-08-10 09:49:15,537 botocore.auth [DEBUG] Calculating signature using v4 auth.
2017-08-10 09:49:15,537 botocore.auth [DEBUG] CanonicalRequest:[redacted]
2017-08-10 09:49:15,539 botocore.auth [DEBUG] StringToSign:[redacted]
2017-08-10 09:49:15,539 botocore.auth [DEBUG] Signature:[redacted]
2017-08-10 09:49:15,540 botocore.endpoint [DEBUG] Sending http request: <PreparedRequest [POST]>
2017-08-10 09:49:15,540 botocore.vendored.requests.packages.urllib3.connectionpool [INFO] Resetting dropped connection: cloudformation.us-west-2.amazonaws.com
2017-08-10 09:49:15,721 botocore.vendored.requests.packages.urllib3.connectionpool [DEBUG] "POST / HTTP/1.1" 200 704
2017-08-10 09:49:15,721 botocore.parsers [DEBUG] Response headers: {'x-amzn-requestid': [redacted]', 'date': 'Thu, 10 Aug 2017 16:49:15 GMT', 'content-length': '704', 'content-type': 'text/xml'}
2017-08-10 09:49:15,721 botocore.parsers [DEBUG] Response body:
<DescribeStacksResponse xmlns="http://cloudformation.amazonaws.com/doc/2010-05-15/">
  <DescribeStacksResult>
    <Stacks>
      <member>
        <CreationTime>2017-08-10T16:48:45.324Z</CreationTime>
        <NotificationARNs/>
        <StackId>[redacted]</StackId>
        <StackName>[redacted]</StackName>
        <StackStatus>ROLLBACK_COMPLETE</StackStatus>
        <DisableRollback>false</DisableRollback>
        <Tags/>
      </member>
    </Stacks>
  </DescribeStacksResult>
  <ResponseMetadata>
    <RequestId>[redacted]</RequestId>
  </ResponseMetadata>
</DescribeStacksResponse>

2017-08-10 09:49:15,723 botocore.hooks [DEBUG] Event needs-retry.cloudformation.DescribeStacks: calling handler <botocore.retryhandler.RetryHandler object at 0x7ff878f64cd0>
2017-08-10 09:49:15,723 botocore.retryhandler [DEBUG] No retry needed.
Traceback (most recent call last):
  File "test.py", line 23, in <module>
    main()
  File "test.py", line 19, in main
    cf.get_waiter('stack_create_complete').wait(StackName=STACKNAME)
  File "/usr/local/lib/python2.7/dist-packages/botocore/waiter.py", line 53, in wait
    Waiter.wait(self, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/botocore/waiter.py", line 321, in wait
    last_response=response,
botocore.exceptions.WaiterError: Waiter StackCreateComplete failed: Waiter encountered a terminal failure state

[joguSD]

What behavior are you expecting from this?

[jarruda]

After looking through the source it appears that this is working as intended. My apologies. I was under the impression that this exception was for unexpected failures instead of ones specific to StackCreateComplete.

Instead I will frame this as a feature request:

I would like to be able to retrieve error information from the WaiterError class, similar to ClientError's API. In my example, there was a CREATE_FAILED event on the stack resource that resulted from my CreateStack call (which subsequently resulted in a rollback) that would be desirable to access after using the waiter. At present, the user has to list the stack events after the wait and obtain the error from there.

[JordonPhillips]

Being able to track the exact reasons for failure states may be tricky. Marking as a feature request.