Database connection refused for Laravel artisan command with Docker - php

Question

I am trying to run Laravel using Docker locally. Everything works fine expect the database. This is how my docker-compose looks like:
services:
app:
build:
context: ./
dockerfile: ./docker/Dockerfile
container_name: my-app
working_dir: /var/www/
volumes:
- ./:/var/www
networks:
- my-network
db:
image: mysql:8.0
container_name: my-db
environment:
MYSQL_DATABASE: ${DB_DATABASE}
MYSQL_ROOT_PASSWORD: ${DB_PASSWORD}
SERVICE_TAGS: dev
SERVICE_NAME: mysql
ports:
- 3307:3306
volumes:
- ./docker/mysql:/docker-entrypoint-initdb.d
networks:
- my-network
nginx:
image: nginx:alpine
container_name: my-nginx
ports:
- 8001:80
volumes:
- ./:/var/www
- ./docker/nginx/nginx.conf:/etc/nginx/conf.d
networks:
- my-network
My .env file looks like this:
DB_CONNECTION=mysql
DB_HOST=db
DB_PORT=3306
DB_DATABASE=laravel
DB_USERNAME=admin
DB_PASSWORD=
When I run php artisan migrate:fresh within the app container, I am getting the following message:
SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo failed: Name or service not known (SQL: SHOW FULL TABLES WHERE table_type = 'BASE TABLE')
Can someone see what is the problem here?
UPDATE: When I run docker-compose ps I can see
NAME COMMAND SERVICE STATUS PORTS
my-app "docker-php-entrypoi…" app running 9000/tcp
my-db "docker-entrypoint.s…" db restarting
my-nginx "/docker-entrypoint.…" nginx running 0.0.0.0:8001->80/tcp, :::8001->80/tcp
This is the log when I run docker-compose logs db
my-db | 2021-07-29T20:18:37.340769Z 0 [System] [MY-013169] [Server] /usr/sbin/mysqld (mysqld 8.0.20) initializing of server in progress as process 104
my-db | 2021-07-29T20:18:37.354423Z 0 [ERROR] [MY-010457] [Server] --initialize specified but the data directory has files in it. Aborting.
my-db | 2021-07-29T20:18:37.354605Z 0 [ERROR] [MY-013236] [Server] The designated data directory /var/lib/mysql/ is unusable. You can remove all files that the server added to it.
my-db | 2021-07-29T20:18:37.356184Z 0 [ERROR] [MY-010119] [Server] Aborting
my-db | 2021-07-29T20:18:37.358746Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.20) MySQL Community Server - GPL.