How to Access Node API within Docker Container

Question

I have a three tier application on Docker tat consists of the following: 1. An Adonis app to server as the api for the application 2. A MongoDB database 3. A NuxtJS app for the client application.

When I run the application locally with docker-compose up it seems to start up just fine. However, when I try to access the api with postman (localhost:3333) or try to access the Next app on my browser (localhost:3000/), I get a "Could not get any response" error and a "Cannot open the page error" respectively.

I have tried exposing the ports within each component's Dockerfile, in addition to specifying port mappings on the docker-compose.yml file.

Here is my Dockerfile for the API application

# The API application

FROM node:alpine
WORKDIR home/api

COPY ./server-api/package.json .
RUN npm install
COPY  ./server-api .

EXPOSE 3333

CMD ["npm", "start"]

Here is the Dockerfile for the NuxtJS application

# The Web application

FROM node:latest
WORKDIR home/app

COPY ./web-client/package.json .
RUN npm install
COPY ./web-client .

EXPOSE 3000

CMD ["npm", "start"]

Here is my docker-compose.yml file

version: '3'

services:

  api:
    build: ./server
    restart: always
    ports:
      - "3333:3333"

  mongodb:
    image: 'mongo'
    restart: always
    environment:
      MONGO_INITDB_ROOT_USERNAME: root
      MONGO_INITDB_ROOT_PASSWORD: NoneOfYourBusiness

  web:
    build: ./web
    restart: always
    ports:
      - "3000:3000"

When I send a GET request to "localhost:3333/" I expect to get a response of "test". However, I am getting a "Could not get any response" error from Postman instead.

When I go to "localhost:3000/" on by browser, I expect to get a page. Instead, it is saying it cannot connect to the server.

Answer 1

If you want to access using localhost, you should share your host network interfaces with dockers. Otherwise, lo iface is different. Definitively, try with this docker-compose:

version: '3'

services:

  api:
    build: ./server
    restart: always
    network_mode: "host"
    ports:
      - "3333:3333"

  mongodb:
    image: 'mongo'
    restart: always
    network_mode: "host"
    environment:
      MONGO_INITDB_ROOT_USERNAME: root
      MONGO_INITDB_ROOT_PASSWORD: NoneOfYourBusiness

  web:
    build: ./web
    restart: always
    network_mode: "host"
    ports:
      - "3000:3000"

Answer 2

From your machine:

You should be able to use localhost:3333 with your current setup. You can double check if a program is listening on the port 3333 (lsof -i:3333 on linux).

From inside your docker:

Set up networks and use the container names to call them, example

version: '3'

networks:
    back:

services:

  api:
    build: ./server
    restart: always
    ports:
      - "3333:3333"
    networks:
      - back
  mongodb:
    image: 'mongo'
    restart: always
    environment:
      MONGO_INITDB_ROOT_USERNAME: root
      MONGO_INITDB_ROOT_PASSWORD: NoneOfYourBusiness
    networks:
      - back
  web:
    build: ./web
    restart: always
    ports:
      - "3000:3000"
    networks:
      - back

From the web container, you could call api:3333 for the api.

BTW, you don't need the EXPOSES 3333 in the Dockerfile since it's already done in the docker-compose file.