how to access phpMyAdmin with docker compose?

Hi
I installed invoiceninja with docker-compose.yml file.
Since I move to another site, I want to create a perfect backup of the site, but I do not have much knowledge so I can not log in to mysql successfully.
I want to access phpMyAdmin instead, but how can I rewrite docker-compose yml specifically?

version: “2”

services:
db:
image: mysql:5
env_file: .env
restart: always
volumes:
- data-volume:/var/lib/mysql

app:
image: invoiceninja/invoiceninja
links:
- db:mysql
env_file: .env
restart: always
volumes:
- ./srv/invoiceninja/storage:/var/www/app/storage:rw
- ./srv/invoiceninja/logo:/var/www/app/public/logo:rw

web:
image: nginx:1
volumes:
- ./nginx.conf:/etc/nginx/nginx.conf:ro
links:
- app
volumes_from:
- app
ports:
- 8000:80

cron:
image: invoiceninja/invoiceninja
links:
- db:mysql
env_file: .env
volumes_from:
- app
entrypoint: |
bash -c ‘bash -s <<EOF
trap “break;exit” SIGHUP SIGINT SIGTERM
sleep 300s
while /bin/true; do
./artisan ninja:send-invoices
./artisan ninja:send-reminders
sleep 1h
done
EOF’

volumes:
data-volume:

You may want to post the question on the dockerfiles repo.

https://github.com/invoiceninja/dockerfiles