deploy multiple services using serverless to Apigateway with shared path - aws-api-gateway

Question

The documentation addresses shared paths:
service: service-b
provider:
apiGateway:
restApiId: xxxxxxxxxx
restApiRootResourceId: xxxxxxxxxx
restApiResources:
/reports: xxxxxxxxxx
functions:
...
However, how can I reference the ID of the resource (the path, that is)? In the first service I have:
Outputs:
apiGatewayRestApiId:
Value:
Ref: ApiGatewayRestApi
Export:
Name: ${self:service}-${opt:stage, 'dev'}-apiGateway-restApiId
apiGatewayRestApiRootResourceId:
Value:
Fn::GetAtt:
- ApiGatewayRestApi
- RootResourceId
Export:
Name: ${self:service}-${opt:stage, 'dev'}-apiGateway-rootResourceId
apiGatewayResourceReports:
Value: !Ref ApiGatewayResource/reports
Export:
Name: ${self:service}-${opt:stage, 'dev'}-apiGateway-reportPath
The first two work, and can be referred to with FN::ImportValue in the 2nd service. However, the third doesn't work. I presume the problem is
that I have to explicitly create the resource ApiGatewayResource/reports
rather than have it created as a side effect of the function definitions in the first service. But how should I do that? And won't it conflict with the function definitions?

Answer 1

After some floundering, I hit upon the following: the first service should
define the resource path, but leave the rest of the gateway definition implicit. And it should output the relevant ids:
provider:
apiGateway:
restApiResources:
/reports: !Ref ReportPath
...
resources:
Resources:
ReportPath:
Type: AWS::ApiGateway::Resource
Properties:
RestApiId: !Ref ApiGatewayRestApi
ParentId:
Fn::GetAtt: [ ApiGatewayRestApi, RootResourceId ]
PathPart: 'reports'
Outputs:
apiGatewayRestApiId:
Value:
Ref: ApiGatewayRestApi
Export:
Name: ${self:service}-${opt:stage, 'dev'}-apiGateway-restApiId
apiGatewayRestApiRootResourceId:
Value:
Fn::GetAtt:
- ApiGatewayRestApi
- RootResourceId
Export:
Name: ${self:service}-${opt:stage, 'dev'}-apiGateway-rootResourceId
apiGatewayResourceReports:
Value: !Ref ReportPath
Export:
Name: ${self:service}-${opt:stage, 'dev'}-apiGateway-reportPath
The 2nd service can reference all three ids:
provider:
apiGateway:
restApiId:
'Fn::ImportValue': crane-mg-reports-${opt:stage, 'dev'}-apiGateway-restApiId
restApiRootResourceId:
'Fn::ImportValue': crane-mg-reports-${opt:stage, 'dev'}-apiGateway-rootResourceId
restApiResources:
/reports:
'Fn::ImportValue': crane-mg-reports-${opt:stage, 'dev'}-apiGateway-reportPath
In both cases, the function definition can define paths using /reports prefix without conflict.