Docker compose (mysql, elasticsearch, kibana) with healthchecks

docker-compose.yml

version: '2.1'
services:
  mysql:
    container_name: mysql
    image: mysql:5.7
    ports:
      - "13306:3306"
    environment:
      - MYSQL_ROOT_PASSWORD=Welcome123
    healthcheck:
        test: ["CMD-SHELL", "mysqladmin -h 'localhost' -u root -pWelcome123 ping --silent"]
        interval: 30s
        timeout: 30s
        retries: 3
    volumes:
      - mysqldata:/var/lib/mysql
    networks:
      - dbnet

  elasticsearch:
    image: elasticsearch:5.3
    container_name: elasticsearch
    depends_on:
      mysql:
          condition: service_healthy
    healthcheck:
        test: ["CMD-SHELL", "curl --silent --fail localhost:9200/_cluster/health || exit 1"]
        interval: 30s
        timeout: 30s
        retries: 3
    environment:
      - "ES_JAVA_OPTS=-Xmx2g -Xms2g"
      - bootstrap.memory_local=true
      - cluster.name=adlp-cluster
    ports:
      - 19200:9200
      - 19300:9300
    volumes:
      - ./elasticsearch/config/elasticsearch.yml:/etc/elasticsearch/config/elasticsearch.yml
      - ./elasticsearch/config/jvm.options:/etc/elasticsearch/config/jvm.options
      - ./elasticsearch/config/log4j2.properties:/etc/elasticsearch/config/log4j2.properties
      - esdata:/usr/share/elasticsearch/data
    networks:
      - esnet
  kibana:
    image: kibana:5.3
    container_name: kibana
    depends_on:
      elasticsearch:
          condition: service_healthy
    ports:
     - "5601:5601"
    environment:
     - ELASTICSEARCH_URL=http://elasticsearch:9200
     - XPACK_MONITORING_ENABLED=false
    depends_on:
     - elasticsearch
    networks:
     - esnet

volumes:
  mysqldata:
    driver: local
  esdata:
    driver: local

networks:
  esnet:
    driver: bridge
  dbnet:
    driver: bridge

Finally, for debugging health checks, the Docker inspect command lets you view the output of commands that succeed or fail (here in JSON format):

docker inspect --format='{{json .State.Health}}' elasticsearch

After the container image is rebuilt and run, the health state is returned in parentheses in the output of docker ps

how does elasticsearch communicate with mysql? They are in 2 different networks. Shouldn't container elasticsearch belong to both esnet and dbnet?