DefinitionUri doesnt support Intrinsic Functions

[shivaman]

I have an external Swagger file (not in S3), and trying to do something like

DefinitionUri: !Ref SwaggerFile
or !Join or !Sub results in

Transform AWS::Serverless-2016-10-31 failed with: Invalid Serverless Application Specification document. Number of errors found: 1. Resource with id [MyAPI] is invalid. 'DefinitionUri' requires Bucket and Key properties to be specified

Whereas DefinitionUri: swagger_development.yml works fine.

https://github.com/awslabs/serverless-application-model/blob/master/HOWTO.md#using-intrinsic-functions seems to claim this should work. This makes working with a SAM template with different configs for development and testing difficult.

[cluggas]

That error is suggesting that the DefinitionUri is not matching an expected regex pattern. It needs a bucket and key, which are parts of an S3 Uri.

I think this has to be an S3 bucket Uri, which is why I am surprised that swagger_development.yml works.

If you want to parametrise DefinitionUri, try building it up from parameters using the !Sub function...

DefinitionUri !Sub s3://${ArtifactsBucket}/swagger_development.yml

[badfun]

I am getting the same error message, but without trying intrinsic functions, just calling the api file. I have done a lot of testing and it seems this part of the documentation is wrong. The example shown here does not work: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#example-awsserverlessapi

A similar example is shown in the Lambda developer guide: http://docs.aws.amazon.com/lambda/latest/dg/deploying-lambda-apps.html

AWSTemplateFormatVersion: '2010-09-09' Transform: AWS::Serverless-2016-10-31 Resources: Api: Type: AWS::Serverless::Api Properties: StageName: prod DefinitionUri: swagger.yml

Has anyone been able to get this to work? Or can it only call an S3 bucket? Interestingly, in CodeStar it references a local file as well, and it works fine.

[badfun]

Found the answer here: https://github.com/awslabs/serverless-application-model/pull/86

If you use the AWS CLI command aws cloudformation package it will do the uploading job for you. But if you are passing a SAM template directly to CloudFormation, DefinitionUri has to be a S3 URI. Technically, the spec accepts only S3 URI for this property.

[sanathkr]

That's correct. "aws cloudformation package" command doesn't de-reference intrinsic functions. Its only the CFN service that can do this.