Docker-compose database table reset - mysql

Question

I am new to docker technology. I use docker-compose in my project and every time I start docker-compose my database tables are reset.
docker-compose.yaml
version: '3'
services:
#PHP Service
app:
build:
context: .
dockerfile: ./docker/php/Dockerfile
image: php-7.4.1-extended
container_name: php
restart: unless-stopped
tty: true
environment:
SERVICE_NAME: app
SERVICE_TAGS: dev
working_dir: /var/www
volumes:
- ./:/var/www
- ./docker/php/local.ini:/usr/local/etc/php/conf.d/local.ini
networks:
- app-network
#Nginx Service
webserver:
image: nginx:alpine
container_name: nginx
restart: unless-stopped
tty: true
ports:
- "80:80"
- "443:443"
volumes:
- ./:/var/www
- ./docker/nginx/conf.d/:/etc/nginx/conf.d/
networks:
- app-network
#MySQL Service
db:
image: mysql:5.7.22
container_name: mysql
restart: unless-stopped
tty: true
ports:
- "3306:3306"
environment:
MYSQL_ROOT_USER: root
MYSQL_ROOT_PASSWORD: root
MYSQL_DATABASE: root
MYSQL_USER: root
MYSQL_PASSWORD: root
SERVICE_TAGS: dev
SERVICE_NAME: mysql
volumes:
- ./docker/mysql/my.cnf:/etc/mysql/my.cnf
networks:
- app-network
#Docker Networks
networks:
app-network:
driver: bridge
#Volumes
volumes:
dbdata:
driver: local
I found an example of docker-compose.yaml file from some sources and made changes on it. What should I do to fix the problem.

Answer 1

Your docker image is storing its data within the image, which isn't persisted. You need to tell Docker to store the data on a volume, instead. This is a bit version-dependent, but something like
#MySQL Service
db:
image: mysql:5.7.22
container_name: mysql
restart: unless-stopped
tty: true
ports:
- "3306:3306"
environment:
MYSQL_ROOT_USER: root
MYSQL_ROOT_PASSWORD: root
MYSQL_DATABASE: root
MYSQL_USER: root
MYSQL_PASSWORD: root
SERVICE_TAGS: dev
SERVICE_NAME: mysql
volumes:
- ./docker/mysql/my.cnf:/etc/mysql/my.cnf
- "./.mysql-data/db:/var/lib/mysql"
And then delete
dbdata:
driver: local