10 Docker Database Best Practices

Docker containers have changed the way we think about packaging and deploying applications. By packaging all dependencies into a single container image, Docker makes it easy to deploy and run applications in any environment.

However, running databases in Docker containers comes with its own set of challenges. In this article, we will discuss 10 best practices for running databases in Docker containers. By following these best practices, you can avoid common pitfalls and ensure that your database deployments are successful.

1. Use a separate container for each process

When you use a single container for multiple processes, it can be difficult to troubleshoot problems because you’re not sure which process is causing the issue. By using separate containers, you can isolate each process and make it easier to identify the source of any problems.

It’s also important to remember that containers are meant to be immutable, so if you need to make changes to your database, you should create a new container rather than trying to modify an existing one.

2. Keep containers lean and mean

When you first set up a Docker container, it’s going to be pretty small. But as you start adding data and files to it, that container is going to grow in size. And the bigger the container gets, the more resources it’s going to need, which can impact performance.

So it’s important to keep your containers as lean as possible by only adding the files and data that you absolutely need. That way, you can minimize the impact on performance and keep your database running smoothly.

3. Run one application per container

When you run multiple applications in the same container, they share the same resources. This can lead to contention and performance issues. For example, if one application is using a lot of CPU, the other applications in the same container will be affected.

Additionally, running multiple applications in the same container makes it more difficult to manage and update those applications. It’s much easier to update and manage a single application in its own container than it is to update and manage multiple applications in the same container.

Finally, by running one application per container, you can make use of Docker’s built-in orchestration features. For example, with Docker Compose, you can define all of your applications in a single file and then spin up all of those applications with a single command.

4. Don’t store data in the container itself

If you store data in the container and then later delete that container, your data is gone. That might not be a big deal if it’s just some test data, but if it’s important production data, you could be in for a world of hurt.

Instead, what you want to do is use a volume to store your data. Volumes are separate from containers, so even if you delete the container, the volume will still exist and your data will be safe.

There are two ways to create a volume: using the docker volume create command or using the -v flag when you run the docker run command.

Once you have a volume created, you can mount it into a container using the -v flag. For example, let’s say you have a volume named my-data and you want to mount it into a container. You would use the following command:

docker run -d –name my-container -v my-data:/data my-image

This would mount the my-data volume into the /data directory inside the container. Now, any data that you write to /data inside the container will actually be written to the my-data volume, and it will persist even if you delete the container.

5. Avoid running databases as root

When you run a database as root, it means that the database has full access to the host machine. This can be a security risk because if there is a vulnerability in the database software, an attacker could potentially gain access to the host machine and all of its data.

It’s also important to avoid running databases as root because it can lead to performance issues. When a database runs as root, it has access to all of the host machine’s resources, which can cause contention with other processes that are running on the host machine.

The best practice is to create a dedicated user for the database, and then run the database as that user. This will limit the database’s access to only the resources it needs, and will help to prevent any potential security risks.

6. Make sure your database is accessible from outside the Docker host

If you’re using Docker for development, you might be tempted to think that you don’t need to worry about this since your database will only be accessed from within the development environment. However, there are several situations where you might need to access the database from outside Docker, such as:

– When you need to run database migrations
– When you need to access the database directly for debugging or troubleshooting purposes
– When you need to use a tool that doesn’t have native support for Docker

Therefore, it’s important to make sure your database is accessible from outside Docker, so you don’t get caught in a situation where you can’t access it when you need to.

There are two main ways to do this:

– Use a reverse proxy server, such as NGINX, to expose the database port to the outside world.
– Use Docker’s built-in port mapping feature to map the database port to a port on the Docker host.

Both of these methods have their own pros and cons, so you’ll need to decide which one is best for your particular situation.

7. Monitor your containers

When you’re using containers in production, it’s important to have visibility into what’s going on inside of them. This means monitoring things like CPU usage, memory usage, and disk IO.

There are a few different ways to do this, but one of the simplest is to use the docker stats command. This will give you a live view of all of your running containers, including their resource usage.

If you want more comprehensive monitoring, there are a number of third-party tools that can help, like Datadog or New Relic.

8. Backup your containers regularly

If you lose your data, you can’t just spin up a new container and start from scratch. You need to have backups in place so that you can restore your data if something goes wrong.

There are two main ways to backup Docker containers:

1. Use a tool like Docker Trusted Registry (DTR) to take snapshots of your containers.

2. Export your containers as tar files and store them in a safe location.

You should ideally do both so that you have multiple backups in different formats. That way, if one method fails, you have another to fall back on.

Backing up your containers regularly is essential, but it’s not the only best practice you need to follow. Keep reading to learn more.

9. Consider using an orchestration tool to manage your containers

When you’re using Docker to containerize your database, you’re essentially packaging your database into a self-contained unit that can be run on any server. However, managing these containers can be a challenge, especially if you have a lot of them.

This is where an orchestration tool like Kubernetes or Docker Compose comes in handy. These tools allow you to manage your Docker containers from a single place, making it much easier to keep track of them and ensuring that they are always running as intended.

While there is some overhead involved in setting up and using these tools, the benefits far outweigh the costs, especially as your number of containers grows.

10. Use volumes to persist data

When you use volumes, the data in your database is stored outside of the Docker container on the host machine. This has a few advantages.

If something happens to the Docker container, like it’s deleted or corrupted, the data is still safe on the host machine. Also, if you need to move the database to another server, you can just copy the data from the host machine to the new server. The data is also accessible on the host machine, so you can take backups easily.

To create a volume, you just need to specify the -v flag when you run the docker run command. For example, to create a volume for MySQL, you would use this command:

docker run -d -v /var/lib/mysql:/var/lib/mysql –name mysql mysql

This will create a volume at /var/lib/mysql on the host machine that will be used by the MySQL container.