How to access Cognito User Pool Arn as a function authorizer?

Serverless Framework
,
5

SOLVED.

I was able to reference an explicitly declared authorizer. In my cognito-user-pool.yml file I added the MyApiGatewayAuthorizer section, ending up with

CognitoUserPool:
    Type: AWS::Cognito::UserPool
    Properties:
      UserPoolName: company-${self:custom.stage}-user-pool

      UsernameAttributes:
        - email
      AutoVerifiedAttributes:
        - email

  MyApiGatewayAuthorizer: 
    Type: AWS::ApiGateway::Authorizer
    Properties: 
      AuthorizerResultTtlInSeconds: 10
      IdentitySource: method.request.header.Authorization
      Name: MyCognitoAuthorizer
      RestApiId: 
        Ref: ApiGatewayRestApi
      Type: COGNITO_USER_POOLS
      ProviderARNs: 
        - {"Fn::Join": ["", ["arn:aws:cognito-idp:", {Ref: "AWS::Region"}, ":", {Ref: "AWS::AccountId"}, ":userpool/", Ref: CognitoUserPool]]}

and in my function event definition, I specified the authorizer as such:

events:
  - http:
      path: target
      method: get
      cors: true
      authorizer:
        type: COGNITO_USER_POOLS
        authorizerId: { Ref: MyApiGatewayAuthorizer }

This worked for me. I hope it can help someone else!

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