Concatenate Websocket API name

Hi! I could get close to what I need with this code:

    WEBSOCKET_ENDPOINT: {
        'Fn::Join': [
          '',
          [
            'https://',
            {
              Ref: 'WebsocketsApi',
            },
            '.execute-api.us-east-1.',
            {
              Ref: 'AWS::URLSuffix',
            },
            '/dev',
          ],
        ],
      }

But here I still have 2 vars hard coded (us-east-1 and /dev). I tried a lot to put them with no sucess.

Any advice on this? both of these vars I have on the yml as {self:provider.region} {self:provider.stage}. How can I concatenate them?

cheers

Just figured out that I was doing wrong… here is the correct code.

                     !Join
                          - ''
                          - - 'https://'
                            - !Ref "WebsocketsApi"
                            - ".execute-api."
                            - !Ref "AWS::Region"
                            - "."
                            - !Ref "AWS::URLSuffix"
                            - "/"
                            - ${self:provider.stage}