Mysql database gone on each docker restart - mysql

Question

Background: I was updating my dockerfile and to make sure it works I rebuild my docker from scratch after purging everything using system prune -a. After it was built successfully I tried making a database called "database_A" and using "show databases" it does show that "database_A" was created. However whenever I restart the container it will be gone and checking using the query "show databases" the database "database_A" does not exist.
This is how I run the mysql container:
echo "runing mysql container..."
docker run --rm -it \
--network host \
-e MYSQL_ROOT_PASSWORD=secret \
--volume $(pwd)/mysql_data:/var/lib/mysql \
--volume $(pwd)/mysql.conf:/etc/mysql/mysql.conf.d \
--name mysql \
-p 3307:3307 \
-d mysql:5.6
in mysql.conf.d/mysqld.cnf it was specified
datadir = /var/lib/mysql
Using the bash terminal on the mysql container I checked the /var/lib/mysql folder and the ibdata1 file wasn't update at all. I tried creating a folder in the /var/lib/mysql and it does shows up in /mysql_data in host. So it's using the right volume but saving in different location? How can I verify it?

Answer 1

Try to use permanent folder for storing mysql db data files. Using $(pwd)/mysql_data seems temporary and dependent of where you run the container.
Below flow shows that created database is retained after container removal and starting new one with the same bind mount:
$ docker run --name some-mysql -v ~/private/mysql-data:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=secret -d mysql:5.6
$docker exec -it some-mysql bash
root#0873b9898e23:/# mysql -uroot -psecret
Welcome to the MySQL monitor...
mysql> crete database test;
Query OK, 1 row affected (0.01 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.01 sec)
mysql> ^DBye
root#0873b9898e23:/# exit
# let's remove the container and create new one
$ docker rm -f some-mysql
some-mysql
$docker run --name some-mysql -v ~/private/mysql-data:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=secret -d mysql:5.6
docker exec -it some-mysql bash
root#6f77e071321e:/# mysql -uroot -psecret
Welcome to the MySQL monitor....
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.01 sec)
Also, note mysql docker docs.