Docker-Compose persistent data MySQL - docker

Question

I can't seem to get MySQL data to persist if I run $ docker-compose down with the following .yml
version: '2'
services:
# other services
data:
container_name: flask_data
image: mysql:latest
volumes:
- /var/lib/mysql
command: "true"
mysql:
container_name: flask_mysql
restart: always
image: mysql:latest
environment:
MYSQL_ROOT_PASSWORD: 'test_pass' # TODO: Change this
MYSQL_USER: 'test'
MYSQL_PASS: 'pass'
volumes_from:
- data
ports:
- "3306:3306"
My understanding is that in my data container using volumes: - /var/lib/mysql maps it to my local machines directory where mysql stores data to the container and because of this mapping the data should persist even if the containers are destroyed. And the mysql container is just a client interface into the db and can see the local directory because of volumes_from: - data
Attempted this answer and it did not work. Docker-Compose Persistent Data Trouble
EDIT
Changed my .yml as shown below and created a the dir ./data but now when I run docker-compose up --build the mysql container wont start throws error saying
data:
container_name: flask_data
image: mysql:latest
volumes:
- ./data:/var/lib/mysql
command: "true"
mysql:
container_name: flask_mysql
restart: always
image: mysql:latest
environment:
MYSQL_ROOT_PASSWORD: 'test_pass' # TODO: Change this
MYSQL_USER: 'test'
MYSQL_PASS: 'pass'
volumes_from:
- data
ports:
- "3306:3306"
flask_mysql | mysqld: Can't create/write to file '/var/lib/mysql/is_writable' (Errcode: 13 - Permission denied)
flask_mysql | 2016-08-26T22:29:21.182144Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
flask_mysql | 2016-08-26T22:29:21.185392Z 0 [ERROR] --initialize specified but the data directory exists and is not writable. Aborting.

Answer 1

The data container is a superfluous workaround. Data-volumes would do the trick for you. Alter your docker-compose.yml to:
version: '2'
services:
mysql:
container_name: flask_mysql
restart: always
image: mysql:latest
environment:
MYSQL_ROOT_PASSWORD: 'test_pass' # TODO: Change this
MYSQL_USER: 'test'
MYSQL_PASS: 'pass'
volumes:
- my-datavolume:/var/lib/mysql
volumes:
my-datavolume:
Docker will create the volume for you in the /var/lib/docker/volumes folder. This volume persist as long as you are not typing docker-compose down -v

Answer 2

There are 3 ways:
First way
You need specify the directory to store mysql data on your host machine. You can then remove the data container. Your mysql data will be saved on you local filesystem.
Mysql container definition must look like this:
mysql:
container_name: flask_mysql
restart: always
image: mysql:latest
environment:
MYSQL_ROOT_PASSWORD: 'test_pass' # TODO: Change this
MYSQL_USER: 'test'
MYSQL_PASS: 'pass'
volumes:
- /opt/mysql_data:/var/lib/mysql
ports:
- "3306:3306"
Second way
Would be to commit the data container before typing docker-compose down:
docker commit my_data_container
docker-compose down
Third way
Also you can use docker-compose stop instead of docker-compose down (then you don't need to commit the container)

Answer 3

first, you need to delete all old mysql data using
docker-compose down -v
after that add two lines in your docker-compose.yml
volumes:
- mysql-data:/var/lib/mysql
and
volumes:
mysql-data:
your final docker-compose.yml will looks like
version: '3.1'
services:
php:
build:
context: .
dockerfile: Dockerfile
ports:
- 80:80
volumes:
- ./src:/var/www/html/
db:
image: mysql
command: --default-authentication-plugin=mysql_native_password
restart: always
environment:
MYSQL_ROOT_PASSWORD: example
volumes:
- mysql-data:/var/lib/mysql
adminer:
image: adminer
restart: always
ports:
- 8080:8080
volumes:
mysql-data:
after that use this command
docker-compose up -d
now your data will persistent and will not be deleted even after using this command
docker-compose down
extra:- but if you want to delete all data then you will use
docker-compose down -v

Answer 4

You have to create a separate volume for mysql data.
So it will look like this:
volumes_from:
- data
volumes:
- ./mysql-data:/var/lib/mysql
And no, /var/lib/mysql is a path inside your mysql container and has nothing to do with a path on your host machine. Your host machine may even have no mysql at all. So the goal is to persist an internal folder from a mysql container.

Answer 5

Adding on to the answer from #Ohmen, you could also add an external flag to create the data volume outside of docker compose. This way docker compose would not attempt to create it. Also you wouldn't have to worry about losing the data inside the data-volume in the event of $ docker-compose down -v.
The below example is from the official page.
version: "3.8"
services:
db:
image: postgres
volumes:
- data:/var/lib/postgresql/data
volumes:
data:
external: true

Answer 6

Actually this is the path and you should mention a valid path for this to work. If your data directory is in current directory then instead of my-data you should mention ./my-data, otherwise it will give you that error in mysql and mariadb also.
volumes:
./my-data:/var/lib/mysql

Answer 7

Feasible bind mount solution:
mariadb:
image: mariadb:latest
restart: unless-stopped
environment:
- MARIADB_ROOT_PASSWORD=${MARIADB_ROOT_PASSWORD}
volumes:
- type: bind
source: /host/dir
target: /var/lib/mysql