client.validate_template return error while aws cloudformation validate-template doesn't

python --version Python 2.7.11 :: Anaconda 2.5.0 (64-bit)

print boto3.version 1.3.0

I’m seeing a problem where boto3 client.validate_template returns ValidationError consistently on any template I tried on; however, aws cloudformation validate-template reads the same templates ok.

In my test.py:

        cfclient = boto3.client('cloudformation')
       response = cfclient.validate_template(TemplateBody='file://mytemplate.json')

and this would return: Traceback (most recent call last): File “./test.py”, line 207, in <module> response = cfclient.validate_template(TemplateBody=‘file:/mytemplate.json’) File “/root/anaconda2/lib/python2.7/site-packages/botocore/client.py”, line 228, in _api_call return self._make_api_call(operation_name, kwargs) File “/root/anaconda2/lib/python2.7/site-packages/botocore/client.py”, line 492, in _make_api_call raise ClientError(parsed_response, operation_name) botocore.exceptions.ClientError: An error occurred (ValidationError) when calling the ValidateTemplate operation: Template format error: JSON not well-formed. (line 1, column 5) NOTE: the error always points to line 1, column 5.

When I run "aws cloudformation validate-template --template-body file://mytemplate.json. It appears to be okay. { “Description”: “Template to launch an instance”, “Parameters”: [] }

I have tried giving the TemplateBody absolute path (file:///root/development/mytemplate.json) or relative path (file://mytemplate.json) and the problem still persists. This lead me to believe that the cause is something else.

My ultimate goal being able to create a stack with the following code with Boto3: response = cfclient.create_stack(StackName='my-stack', TemplateBody=tdmctemplate)

Currently, this statement will fail on the same error.

[kyleknap]

I think this a similar solution. You cannot provide the filename, you need to open the file and pass its contents to the parameter. So something like:

cf = boto3.client('cloudformation')
with open('mytemplate.json', 'r') as f:
    resp = cf.create_stack(StackName=stack_name, TemplateBody=f.read())

[kyleknap]

So you cannot use the file:// from the CLI. We only have this in the CLI because there is not a good way of getting the contents of the file from the command line. For boto3, you will have to open a file yourself and read its contents. So something like this:

cfclient = boto3.client('cloudformation')
with open('mytemplate.json', 'r') as f:
    response = cfclient.validate_template(TemplateBody=f.read())

Let us know if that helps.