【Rails】rails6 + docker + nuxt ssr で connect ECONNREFUSED ERROR socket hang up

rails + docker + nuxtでなにか作ろうとしていた際にハマった部分
時間があるときに詳細を書きたい。

docker-compose.yml

version: '3'
services:
  db:
    image: mysql:8.0
    environment:
      MYSQL_ROOT_PASSWORD: password
    ports:
      - '3306:3306'
    command: --default-authentication-plugin=mysql_native_password
    volumes:
      - mysql-data:/var/lib/mysql
  backend:
    build: ./backend/
    command: bash -c "rm -f tmp/pids/server.pid && bundle install && bundle exec rails s -p 3000 -b '0.0.0.0'"
    volumes:
      - .:/app
    ports:
      - "3000:3000"
    depends_on:
      - db
    stdin_open: true
    tty: true
    command: bundle exec rails server -b 0.0.0.0
  frontend:
    build: ./frontend/
    command: npm run dev
    volumes:
      - .:/app
    ports:
      - 8080:3000
volumes:
  mysql-data:
    driver: local

frontend/pages/users/_id.vue

<template>
  <h1>Hello, {{ id }}</h1>
</template>

<script>
export default {
  asyncData ({ $axios, params }) {
    return $axios.$get(`http://localhost:3000/users/${params.id}`).then((res) => {
      return { id: res.id }
    })
  }
}
</script>

ブラウザからapi(http://localhost:3000/users/1) を叩くと

{
id: 1,
email: "[e-mail]",
created_at: "2020-02-29T13:39:03.638Z",
updated_at: "2020-02-29T13:39:12.055Z",
url: "http://localhost:3000/users/1"
}

vueのfront(http://localhost:8080/users/1) からアクセスすると

frontend_1  |  ERROR  socket hang up
frontend_1  | 
frontend_1  |   at connResetException (internal/errors.js:604:14)
frontend_1  |   at Socket.socketOnEnd (_http_client.js:460:23)
frontend_1  |   at Socket.emit (events.js:323:22)
frontend_1  |   at Socket.EventEmitter.emit (domain.js:482:12)
frontend_1  |   at endReadableNT (_stream_readable.js:1204:12)
frontend_1  |   at processTicksAndRejections (internal/process/task_queues.js:84:21)

以下に書き換える

frontend/pages/users/_id.vue

<template>
  <h1>Hello, {{ id }}</h1>
</template>

<script>
export default {
  asyncData ({ $axios, params }) {
    return $axios.$get(`http://backend:3000/users/${params.id}`).then((res) => {
      return { id: res.id }
    })
  }
}
</script>

Request failed with status code 403

railsを以下を追加

backend/config/environments/development.rb

  config.hosts << "backend"

解決した。