Containers make software engineering easier and more efficient, and Docker containers are popular and easy to use.

Containers are essential for local development. They let you test-run your applications in local environments and start building out the required infrastructure.

Docker containers are immutable by nature. This means that restarting a container erases all your stored data in the container. But Docker provides volumes and bind mounts, which are two mechanisms for persisting data in your Docker container.

This tutorial will teach you how to bind local directories to your Docker container and use docker-managed volumes alternatively. Knowing both enables you to use Docker containers for many more use cases that can boost your productivity.

How to Mount Local Directories using docker run -v

The docker run command first creates a writeable container layer over the specified image and then starts using the specified command. (Source

Using the parameter -v allows you to bind a local directory.

-v or --volume allows you to mount local directories and files to your container. For example, you can start a MySQL database and mount the data directory to store the actual data in your mounted directory.

# run mysql container in the background

$ docker run --name mysql-db -v $(pwd)/datadir:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=my-secret-pw -d mysql:8.0.28-debian

# show content of data directory
$ ls -la datadir
total 383848
-rw-r-----    1 sebarthel  staff    196608 Mar 26 22:47 #ib_16384_0.dblwr
-rw-r-----    1 sebarthel  staff   8585216 Mar 26 22:47 #ib_16384_1.dblwr
drwxr-x---   12    sebarthel  staff       384 Mar 26 22:47 #innodb_temp
drwxr-xr-x@  27 sebarthel  staff       864 Mar 26 22:47 .
drwxr-xr-x    3 sebarthel  staff        96 Mar 26 22:47 ..
-rw-r-----    1 sebarthel  staff        56 Mar 26 22:47 auto.cnf
-rw-r-----    1 sebarthel  staff       913 Mar 26 22:47 binlog.000001
(more directories)

# stop mysql container
docker rm -f mysql-db

Binding a directory is a 2-way sync. Every file you change on the host is changed in the container, and every file that is changed in the container is changed on the host. So if you stop and start the database, you can mount the same directory, and your configuration and stored data will be available.

The advantages of this method are that it’s straightforward to use and easy to access. You should use binding local directories for files you want to change or observe on the host, like configuration files and log files.

How to Use Docker Volumes to Persist Changes

Instead of binding your local directory, you can use Docker volumes. A Docker volume is a directory somewhere in your Docker storage directory and can be mounted to one or many containers. They are fully managed and do not depend on certain operating system specifics.

Let’s create a Docker volume and mount it to persist MySQL data:

# create volume
docker volume create mysql-data

# run mysql container in the background
$ docker run --name mysql-db -v mysql-data:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=my-secret-pw -d mysql:latest

# stop mysql container
docker rm -f mysql-db

# remove volume
docker volume remove mysql-data

Before removing the Docker volume, you can open your Docker GUI and inspect the volume by clicking on the data tab.


You see the files, but they're isolated in a Docker volume. It’s recommended to use them for persisting files that you don’t need to observe or change from your host system. This method is known to have better performance than local directory bindings.


Docker containers get more powerful when you know how to persist your data and not to lose them when stopping a container.

You bind local directories and volumes to a container by providing the Docker run -v parameter. You need to give the absolute local path or a volume name and map it to a directory within the container -v <source>:<target>.

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