Instead you’ll need to use docker ps -a to view the container: ~> docker ps -a | grep mysqlĮc48ddda196e mysql:5 "/entrypoint.sh mysq 2 days ago mysql_dataĭocker allows to mount, or pull in, volumes from other containers using -volumes-from switch specified when running the container. Since this container is not running, it will not be visible with just docker ps. If you intend to use MySQL, then this data-only container can be created as: docker create -name mysql_data arungupta/mysql-data-containerĭockerfile for this container is pretty simple and can be adopted for a database server of your choice. You can adjust this command for whatever database container you are using. If you plan to use a MySQL container later, its recommended to use the mysql image to save bandwidth and space from downloading another random image. These containers don’t even need to start or run, and so the command really is irrelevant, just creating them is enough.Ĭreate the container as: docker create -name mysql_data -v /var/lib/mysql mysql Docker Data-only containers are NoOp containers that perform a command that is not really relevant, and instead mount volumes that are used for storing data. Meet Docker data-only containers! Docker Data-only Containersĭocker follows Single Responsibility Principle (SRP) really well. That means, you once again loose the big benefit of portability as offered by Docker. ![]() It restricts MySQL to a particular Boot2Docker VM image. It’ll be great if somebody who has tried that configuration can share that recipe.īut as mentioned before, this approach is host-centric. This might be configured using master/slave configuration, where the master and slave have access to same volume. So you need to make sure to stop an existing MySQL container, start a new MySQL container using the same volume, and the data would still be accessible. 02:35:58 1 InnoDB: Retrying to lock the first data file 02:35:58 1 InnoDB: Check that you do not already have another mysqld process using the same InnoDB data or log files. Remember, multiple MySQL containers cannot access this shared mount together and instead will give the error: 02:35:58 1 InnoDB: Unable to lock. Now any additional runs of the container can mount the same volume and will have access to the data. Start a MySQL container as: docker run -name mysqldb -e MYSQL_USER=mysql -e MYSQL_PASSWORD=mysql -e MYSQL_DATABASE=sample -e MYSQL_ROOT_PASSWORD=supersecret -d mysqlĪnd inspect as: docker inspect -f cd7deacc9d18 Lets see the default location where MySQL Docker container stores the data. Default Data Location of MySQL Docker Container This blog shows different approaches of Docker MySQL Persistence – across container restarts and accessible from multiple containers. So even though MySQL containers can be used as explained in the recipe, DDL/DML commands can be used to persist data, but that state is lost, or at least not accessible, after the container is terminated and removed. Docker containers are ephemeral, and so any state stored in them is gone after they are terminated and removed. Notify me of follow-up comments by email.One of the recipes in 9 Docker recipes for Java developers is using MySQL container with WildFly. Save my name, email, and website in this browser for the next time I comment. Your email address will not be published. var/lib/mysql will end up in relative safety of host FS: We can map host directory to container’s data directory, so anything mysql writes to e.g. Imagine you you’re running mysql container and want to preserve its data files during upgrades, or just perform occasional backups. The simplest approach is mounting arbitrary host directory to container’s FS. There’re several approaches of how to use Docker volumes and today we’ll take a look at three of them. As it no longer belongs to container’s FS, it’s not a problem to delete one container, create another one and mount existing data volume to it. ![]() Generally speaking, Docker volume is just a host directory mounted to container’s file system. However, along with the problem Docker also provides a solution: Docker volumes. What will you do with its database files? In containers world “upgrade” means “nuke an old one, start a new one” and your data will turn into radioactive ashes with the rest of container’s file system. Imagine you have MySQL container which you decided to upgrade. As Docker containers supposed to be small, single process and easy replaceable instances, it’s not particularly clear how persistent data fits into that picture.
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