Docker-Compose persistent data MySQL
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.
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The data container is an 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
There are 3 ways:
First. You need specify directory to store mysql data on your host machine. You can remove data container. Your mysql data will be saved on you local filesystem.
Mysql container definition must looks 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 is commit 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 commit container)
You have to create an 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.