![]() busybox is the name of the image we’re using to create the container.-v myvolume:/vol mounts the myvolume volume to the path /vol inside the container. ![]() This is useful for cleanup since we’re only creating this container to peek into the volume. -rm tells Docker to remove the container after it exits.-it tells Docker to run the container in interactive mode so you can interact with the BusyBox shell.docker run is the command to create and start a new container.Here’s the command: docker run -it -rm -v myvolume:/vol busybox ls /vol For this purpose, we can use a lightweight image like busybox. We can create and run a temporary container which mounts myvolume. Let’s say we have a volume named myvolume and we want to view its contents. So, how can we view the data? The answer is by creating a new Docker container that has the volume attached, and then exploring the data from within this new container. However, the data is not easily accessible and it’s not recommended to directly interact with these directories, as Docker manages them. Each volume is represented by a directory within this folder. On a typical Linux installation, Docker stores the data in volumes in the following directory on the host machine: /var/lib/docker/volumes/. Now that you’re familiar with Docker volumes and how to use them with Docker Compose, you might be wondering, “How can I actually view the data inside a Docker volume?” In this section, I will guide you through the steps to do exactly that.įirstly, it’s important to understand where Docker volumes are stored. How can I view the data inside a Docker volume? After doing this, you should see that the table you created still exists, which means your data has persisted. To verify that the data is persisting, you could create a table in the MySQL database, then stop and remove the containers with docker-compose down, and then bring them back up again with docker-compose up -d. If the container is stopped or deleted, the data will remain intact and can be used by new containers. With this configuration, any data that your MySQL server writes to /var/lib/mysql will be stored in the db_data volume. The -d flag tells Docker Compose to run the containers in the background. We’re also setting an environment variable MYSQL_ROOT_PASSWORD to specify the root password for the MySQL server.Īfter you’ve created this file, you can start your MySQL container with Docker Compose by running the following command in the same directory as your docker-compose.yml file: docker-compose up -d The volumes field mounts a volume named db_data at /var/lib/mysql, which is where MySQL stores its data by default. Here we’re defining a single service named db using the mysql:8 image. We’re going to create a docker-compose.yml file with the following content: version: '3' I’ll walk you through an example of creating a persistent MySQL database using Docker Compose. Now let’s put what you’ve learned into practice. Example: Creating a Persistent MySQL Database The volumes field at the root level of the configuration file declares the myvolume volume. The volumes field under the myservice specifies that a volume named myvolume should be mounted at /path/in/container within the running container. In this configuration, we’re creating a service named myservice using an image named myimage. To use a volume in Docker Compose, you need to define it in your docker-compose.yml file. It uses a YAML file (usually named docker-compose.yml) to define the multi-container setup. Now that you understand what Docker volumes are, let’s see how to use them in Docker Compose.ĭocker Compose is a tool that simplifies the process of managing multi-container Docker applications. Furthermore, the data in the volume continues to exist even if no containers are currently using it. This means any changes in this folder can be seen by all linked containers, providing a way to share data between containers. ![]() They are like dedicated folders lying on the host filesystem that can be connected to one or more containers. However, what if we need our data to persist beyond the lifespan of a single container instance? That’s where Docker volumes come into play.ĭocker volumes are essentially a mechanism that allows data to persist even after a container is stopped or deleted. In the world of Docker, data is usually ephemeral, meaning it only exists for the lifespan of the container.
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