Cognito user pool authorizer With Serverless Framework

Question

I need to authorize my API end point using aws cognito userpool. I can do it manually, but I need to automate the authorization part with the serverless framework.

Answer 1

Yes . Serverless (v1.5) support to Cognito user pool authorizer.

If you use previous version of serverless you have to update v1.5 or later.

For the user-pool authorization of api end point you have to specify pool arn.

functions:
  hello:
    handler: handler.hello
    events:
      - http:
          path: hello
          method: get
          integration: lambda
          authorizer:
            name: authorizer
            arn: arn:aws:cognito-idp:us-east-1:123456789:userpool/us-east-1_XXXXXX

More details read this article.

Answer 2

If you want to set the authorizer to a Cognito User Pool you have declared in your resources you must use CloudFormation to create the authorizer as well.

functions:
  functionName:
    # ...
    events:
      - http:
          # ...
          authorizer: 
             type: COGNITO_USER_POOLS
             authorizerId: 
               Ref: ApiGatewayAuthorizer

resources:
  Resources:
    ApiGatewayAuthorizer: 
      Type: AWS::ApiGateway::Authorizer
      Properties: 
        Name: CognitoUserPool
        Type: COGNITO_USER_POOLS
        IdentitySource: method.request.header.Authorization
        RestApiId: 
          Ref: ApiGatewayRestApi
        ProviderARNs: 
          - Fn::GetAtt:
              - UserPool
              - Arn

    UserPool:
      Type: AWS::Cognito::UserPool

Answer 3

Serverless 1.35.1

In case someone stumbles across this how I did. Here is my working solution.

Wherever you create the user pool, you can go ahead and add ApiGatewayAuthorizer

# create a user pool as normal
CognitoUserPoolClient:
  Type: AWS::Cognito::UserPoolClient
  Properties:
    # Generate an app client name based on the stage
    ClientName: ${self:custom.stage}-user-pool-client
    UserPoolId:
      Ref: CognitoUserPool
   ExplicitAuthFlows:
   - ADMIN_NO_SRP_AUTH
   GenerateSecret: true

# then add an authorizer you can reference later
ApiGatewayAuthorizer:
  DependsOn:
  # this is pre-defined by serverless
  - ApiGatewayRestApi
  Type: AWS::ApiGateway::Authorizer
  Properties:
    Name: cognito_auth
    # apparently ApiGatewayRestApi is a global string
    RestApiId: { "Ref" : "ApiGatewayRestApi" }
    IdentitySource: method.request.header.Authorization
    Type: COGNITO_USER_POOLS
    ProviderARNs:
    - Fn::GetAtt: [CognitoUserPool, Arn]

Then when you define your functions

graphql:
  handler: src/app.graphqlHandler
  events:
  - http:
    path: /
    method: post
    cors: true
    integration: lambda
    # add this and just reference the authorizer
    authorizer:
      type: COGNITO_USER_POOLS
      authorizerId:
        Ref: ApiGatewayAuthorizer