Docker: how to set up proxying?

Question

Web development

I need to set up proxying between docker containers. In my variation of the container, they are accessible from the host machine, but they do not see each other. What am I doing wrong? How right?

version: "2.4"
services:
  nginx:
    image: nginx:1.17.2-alpine
    container_name: nginx
    volumes:
      - ./default.nginx:/etc/nginx/conf.d/default.conf
    ports:
      - 8989:8989

  frontend:
    container_name: frontend
    environment:
      - VIRTUAL_HOST=localhost:3000
    build:
      context: ./frontend
      dockerfile: Dockerfile
    ports:
      - 3000:3000

  backend:
    container_name: backend
    environment:
      - VIRTUAL_HOST=localhost:1337
    build:
      context: ./backend
      dockerfile: Dockerfile
    ports:
      - 1337:1337

front

FROM keymetrics/pm2:latest-alpine

ENV NPM_CONFIG_LOGLEVEL error

WORKDIR /usr/src/app

RUN apk update && apk upgrade && apk add --no-cache bash git openssh
RUN apk --no-cache add curl

COPY . .

RUN yarn install
RUN yarn build:ssr

EXPOSE 3000 1337

CMD [ "pm2-runtime", "start", "pm2.json" ]</blockquote>

back 
<blockquote>FROM strapi/base:latest

RUN yarn global add strapi

RUN mkdir /srv/app && chown 1000:1000 -R /srv/app
RUN apk --no-cache add curl

WORKDIR /srv/app

EXPOSE 1337 3000

COPY . .

RUN yarn

# CMD ["strapi", "develop"]
CMD ["strapi", "start"]

default.nginx

server {
    listen 8989;
    server_name localhost;

    location / {
        proxy_pass       http://frontend:3000;
        proxy_set_header Host      $host;
        proxy_set_header X-Real-IP $remote_addr;
    }

    location localhost:3000 {
        proxy_pass       http://frontend:3000;
        proxy_set_header Host      $host;
        proxy_set_header X-Real-IP $remote_addr;
    }
    location localhost:3000/graphql {
        proxy_pass       http://backend:1337/graphql;
#         proxy_pass       http://backend:1337;
        proxy_set_header Host      $host;
        proxy_set_header X-Real-IP $remote_addr;
    }
      location ^~/graphql {
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_set_header Host $http_host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Frame-Options SAMEORIGIN;

#         proxy_pass http://backend:1337/graphql;
        proxy_pass http://localhost:1337/graphql;

      }

    location localhost:1337 {
        proxy_pass       http://backend:1337;
        proxy_set_header Host      $host;
        proxy_set_header X-Real-IP $remote_addr;
    }


    # location ~ /\.ht {
    #     deny  all;
    # }
}

Answer 1

Posted the correct configs on github:
https://github.com/StekolschikovV/Docker-nginx-str...

Answer 2

Read here:
https://docs.docker.com/compose/networking/
In short, add to each container:

network:
    - mynetwork

And register this network:

networks:
  mynetwork:

Answer 3

In docker-compose.yml for nginx, you need to add a dependency on other containers:

nginx:
    #...
    links:
        - frontend
        - backend

Thus, inside the nginx container, the frontend and backend domains will become available and you can refer to them in the nginx configuration.