App-Search failed to connect to Elasticsearch backup

Hi anyone solved or encounter issue with app-search?

[2020-03-09T13:31:14.528+00:00][14][2002][app-server][INFO]: Failed to connect to Elasticsearch backend. Make sure it is running.

app-search7.6.1:

    image: docker.elastic.co/app-search/app-search:7.6.1

    container_name: app-search7.6.1

    hostname: app-search7.6.1

    restart: always

    links:

      - elasticsearch7.6.1

      - kibana7.6.1

    depends_on:

      - elasticsearch7.6.1

      - kibana7.6.1

    user: root #To read the docker socket

    ports:

      - 38887:3002

    expose: 

      - 38887

    environment:

      - secret_session_key=supersecretsessionkey

      - setup.kibana.host=["http://kibana7.6.1:5601"]

      - output.elasticsearch.hosts=["http://elasticsearch7.6.1:9200"]

      - "allow_es_settings_modification=true"

      - "JAVA_OPTS=-Xmx256m -Xmx256m"

    networks:

        - elastic

setup.kibana.hosts and output.elasticsearch.hosts are not App Search config options.
You can see what they are called in App Search here; my guess is that you have to remove setup.kibana.hosts and then replace

- output.elasticsearch.hosts=["http://elasticsearch7.6.1:9200"]

with

- elasticsearch.host=http://elasticsearch7.6.1:9200