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Docker Persistence: When and How to Keep Your Container Data


This content originally appeared on DEV Community and was authored by Farouk BENNACEUR

Containers are designed to be lightweight, fast, and ephemeral by nature. But what happens when your app needs to retain data between restarts or share files with other containers? That’s where Docker persistence comes in.

A container is considered disposed (or removed) when it is explicitly deleted with docker rm, or when it’s started with the --rm flag and stops running. In both cases, any data written inside the container that is not stored in a volume will be lost.

🔢 When Should You Persist Container Data?

✅ Persist Data When:

  • Your application generates data that must survive container restarts (e.g., database data).
  • You want to share data between containers.
  • You need to back up or migrate container data.

❌ Do Not Persist When:

  • The container is stateless (e.g., an API service, a compute worker).
  • You need temporary cache or test data.
  • You want to ensure full isolation and reproducibility.

Persisting unnecessarily can lead to data bloat, complexity, and coupling between host and container.

📁 Docker Volume Types and Use Cases

Docker provides several ways to manage persistent data. Here are the main volume types:

1. Named Volumes (Managed Volumes)

  • Created by Docker and stored in its internal directory (e.g., /var/lib/docker/volumes).
  • Portable and easy to back up.

Use When:

  • You want durable data without caring about host path details.
  • Running databases, persistent app data. 
docker volume create my_data
docker run -v my_data:/app/data my_image

2. Bind Mounts

  • Mount a specific path on the host into the container.
  • Allows real-time access to host files.

Use When:

  • You need to edit files from your host (e.g., during development).
  • Config files need to be versioned on the host. 
docker run -v /path/to/config:/app/config my_image

3. tmpfs Mounts

  • Stored in RAM, lost when the container stops.
  • No disk I/O, high-speed access.

Use When:

  • You need fast access to sensitive or temporary data like passwords. 
docker run --tmpfs /run/cache:rw my_image

✅ Final Thoughts

Not every container needs persistent storage. But when it does, Docker gives you flexible, powerful tools:

  • Use named volumes for standard persistent data.
  • Use bind mounts for full control and local development.
  • Use tmpfs when speed or security is a priority.

Manage them wisely, and your containers will be both clean and capable.


This content originally appeared on DEV Community and was authored by Farouk BENNACEUR