Can not connect mysql with laravel (docker)

Question

I'm very new to laravel and docker and trying to connect mysql to php container(laravel). I thought set right my docker-compose.yml and env file in laravel project.

Also, I can connect to mysql db inside the container.

Here is a error when I did php artisan migrate :

SQLSTATE[HY000] [2002] Connection refused (SQL: select * from information_schema.tables where table_schema = myapp and table_name = migrations and table_type = 'BASE TABLE')

Can anyone know what happened?

docker-compose.yml

version: '3'

services:
  php:
    container_name: php
    build: ./docker/php
    volumes:
    - ./myapp/:/var/www


  nginx:
    image: nginx:latest
    container_name: nginx
    ports:
    - 80:80
    volumes:
    - ./myapp/:/var/www
    - ./docker/nginx/default.conf:/etc/nginx/conf.d/default.conf
    depends_on:
    - php

  db:
    image: mysql:8.0
    container_name: db
    environment:
      MYSQL_ROOT_PASSWORD: root1234
      MYSQL_DATABASE: myapp
      MYSQL_USER: docker
      MYSQL_PASSWORD: docker
      TZ: 'Asia/Tokyo'
    command: mysqld --character-set-server=utf8mb4 --collation-server=utf8mb4_unicode_ci
    ports:
    - 3306:3306

env

DB_CONNECTION=mysql
DB_HOST=127.0.0.1
DB_PORT=3306
DB_DATABASE=myapp
DB_USERNAME=docker
DB_PASSWORD=docker

Answer 1

finally this problem is solved. I changed .env DB_HOST=127.0.0.1 to DB_HOST=db then it's work!!

" DB_HOST= service name of mysql container on docker-compose.yml "

this time my mysql container name is db, so needed to DB_HOST to be db.