docker-compose up でコンテナを起動したが、localhost　で開けない

dockerを使って、既存のrailアプリをコンテナで動かしたいと考えています。

dockerfile
docker-composr.yml　でアプリとdbの連携をしました。

docker-compose up　で、うまく起動できたと思ったのですが、localhost:3000で接続確認をしようとしても、接続を拒否されてしまいます。

ターミナル

app_1  | Puma starting in single mode...
app_1  | * Version 4.3.1 (ruby 2.5.1-p57), codename: Mysterious Traveller
app_1  | * Min threads: 5, max threads: 5
app_1  | * Environment: development
app_1  | * Listening on tcp://0.0.0.0:3000
app_1  | Use Ctrl-C to stop

dockerfile

FROM ruby:2.5.1

RUN apt-get update && \
    apt-get install -y mysql-client nodejs vim --no-install-recommends && \
    rm -rf /var/lib/apt/lists/*

RUN mkdir /myproject

WORKDIR /myproject

ADD Gemfile /myproject/Gemfile
ADD Gemfile.lock /myproject/Gemfile.lock

RUN gem install bundler
RUN bundle install

ADD . /myproject

docker-compose

version: '2'
services:
  db:
    image: mysql:5.6
    environment:
      MYSQL_DATABASE: dbname
      MYSQL_ROOT_PASSWORD: P@ssw0rd
    volumes:
      - mysql-data:/var/lib/mysql
    ports:
      - "4306:3306"

  app:
    tty: true
    stdin_open: true
    build: .
    command: bundle exec rails s -p 3000 -b '0.0.0.0'
    volumes:
      - .:/myproject
      - bundle:/usr/local/bundle
    links:
      - db

volumes:
  mysql-data:
  bundle:

database.yml

default: &default
adapter: mysql2
encoding: utf8
pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
username: root
password:password
host: db


気になったのが、データベースがの部分ですが、エラーはでていないので、問題ないと思うのですが。。。

PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER !
db_1   | To do so, start the server, then issue the following commands:
db_1   | 
db_1   |   /usr/bin/mysqladmin -u root password 'new-password'
db_1   |   /usr/bin/mysqladmin -u root -h f210024dcd38 password 'new-password'
db_1   | 
db_1   | Alternatively you can run:
db_1   | 
db_1   |   /usr/bin/mysql_secure_installation
db_1   | 
db_1   | which will also give you the option of removing the test
db_1   | databases and anonymous user created by default.  This is
db_1   | strongly recommended for production servers.
db_1   | 
db_1   | See the manual for more instructions.
db_1   | 
db_1   | Please report any problems at http://bugs.mysql.com/
db_1   | 
db_1   | The latest information about MySQL is available on the web at
db_1   | 
db_1   |   http://www.mysql.com
db_1   | 
db_1   | Support MySQL by buying support/licenses at http://shop.mysql.com
db_1   | 
db_1   | Note: new default config file not created.
db_1   | Please make sure your config file is current

どなたか、原因が分かる方、いらっしゃいませんか？