httpoison cannot access elasticsearch from webapp in a docker environment

Question

When trying to bring up a project with a webapp (using elixir/ecto as backend language),a postgres database, elasticsearch, and kibana using following docker-compose.yaml file:

version: '3'
services:
  registry:
    restart: always
    image: registry:2
    ports:
      - 443:443
    volumes:
      - /path/data:/var/lib/registry
      - /path/certs:/registry/certs
      - /path/auth:/registry/auth
  webapp:
    build:
      context: ../../../
      dockerfile: config/docker/dev/Dockerfile-dev
    container_name: MyWebApp-dev
    image: 'localhost:443/123'
    environment:
      - ELASTICSEARCH_URL=http://localhost:9200
      - ELASTICSEARCH_HOST=localhost
    ports:
      - "4000:4000"
      - "3000:3000"
    depends_on:
      - db
      - elasticsearch
      - kibana
    networks:
      - esnet
  db:
    image: postgres:10
    container_name: db
    environment:
      - POSTGRES_USER=paul
      - POSTGRES_PASSWORD=SilviaZita1
      - POSTGRES_DB=snitch_dev
    networks:
      - esnet
  elasticsearch:
    image: docker.elastic.co/elasticsearch/elasticsearch:7.0.1
    container_name: elasticsearch
    environment:
      - node.name=elasticsearch
      - discovery.seed_hosts=es02
      - cluster.initial_master_nodes=elasticsearch,es02
      - cluster.name=docker-cluster
      - bootstrap.memory_lock=true
      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
    ulimits:
      memlock:
        soft: -1
        hard: -1
    volumes:
      - esdata01:/usr/share/elasticsearch/data
    ports:
      - 9200:9200
      - 9300:9300
    networks:
      - esnet
  es02:
    image: docker.elastic.co/elasticsearch/elasticsearch:7.0.1
    container_name: es02
    environment:
      - node.name=es02
      - discovery.seed_hosts=elasticsearch
      - cluster.initial_master_nodes=elasticsearch,es02
      - cluster.name=docker-cluster
      - bootstrap.memory_lock=true
      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
    ulimits:
      memlock:
        soft: -1
        hard: -1
    volumes:
      - esdata02:/usr/share/elasticsearch/data
    networks:
      - esnet

  kibana:
    image: docker.elastic.co/kibana/kibana:7.0.1
    ports:
      - "5601:5601"
    container_name: kibana
    environment:
      - ELASTICSEARCH_URL=http://elasticsearch:9200
      - ELASTICSEARCH_HOST=elasticsearch
    depends_on:
    - elasticsearch
    networks:
      - esnet

volumes:
  esdata01:
    driver: local
  esdata02:
    driver: local

networks:
  esnet:  

,

I am getting following error:

** (Mix) Index products could not be created. MyWebApp-dev | MyWebApp-dev | %HTTPoison.Error{id: nil, reason: :econnrefused}

Does anyone know how to solve this problem?

Answer 1

I believe you are getting this connection refused error when you are trying to access elasticsearch from your webapp .

Using localhost inside a container refers to itself. In docker-compose, if you want to access another service which is listening in a particular port, then you have to frame your URL like http://<service-name>:<port>

In your case:

If you want to access elasticsearch service which is listening on 9200 from webapp container, then your URL should be http://elasticsearch:9200

In your webapp service definition, for ELASTICSEARCH_URL and ELASTICSEARCH_HOST use elasticsearch instead of localhost .

Use the below compose file:

version: '3'
services:
  registry:
    restart: always
    image: registry:2
    ports:
      - 443:443
    volumes:
      - /path/data:/var/lib/registry
      - /path/certs:/registry/certs
      - /path/auth:/registry/auth
  webapp:
    build:
      context: ../../../
      dockerfile: config/docker/dev/Dockerfile-dev
    container_name: MyWebApp-dev
    image: 'localhost:443/123'
    environment:
      - ELASTICSEARCH_URL=http://elasticsearch:9200
      - ELASTICSEARCH_HOST=elasticsearch
    ports:
      - "4000:4000"
      - "3000:3000"
    depends_on:
      - db
      - elasticsearch
      - kibana
    networks:
      - esnet
  db:
    image: postgres:10
    container_name: db
    environment:
      - POSTGRES_USER=paul
      - POSTGRES_PASSWORD=SilviaZita1
      - POSTGRES_DB=snitch_dev
    networks:
      - esnet
  elasticsearch:
    image: docker.elastic.co/elasticsearch/elasticsearch:7.0.1
    container_name: elasticsearch
    environment:
      - node.name=elasticsearch
      - discovery.seed_hosts=es02
      - cluster.initial_master_nodes=elasticsearch,es02
      - cluster.name=docker-cluster
      - bootstrap.memory_lock=true
      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
    ulimits:
      memlock:
        soft: -1
        hard: -1
    volumes:
      - esdata01:/usr/share/elasticsearch/data
    ports:
      - 9200:9200
      - 9300:9300
    networks:
      - esnet
  es02:
    image: docker.elastic.co/elasticsearch/elasticsearch:7.0.1
    container_name: es02
    environment:
      - node.name=es02
      - discovery.seed_hosts=elasticsearch
      - cluster.initial_master_nodes=elasticsearch,es02
      - cluster.name=docker-cluster
      - bootstrap.memory_lock=true
      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
    ulimits:
      memlock:
        soft: -1
        hard: -1
    volumes:
      - esdata02:/usr/share/elasticsearch/data
    networks:
      - esnet

  kibana:
    image: docker.elastic.co/kibana/kibana:7.0.1
    ports:
      - "5601:5601"
    container_name: kibana
    environment:
      - ELASTICSEARCH_URL=http://elasticsearch:9200
      - ELASTICSEARCH_HOST=elasticsearch
    depends_on:
    - elasticsearch
    networks:
      - esnet

volumes:
  esdata01:
    driver: local
  esdata02:
    driver: local

networks:
  esnet: