How to Mount a Host Directory in a Docker Container

TLDR

Use the -v or --volume flag with docker run to mount a host directory into your container. This is useful for sharing code, data, or configuration files between your system and the container.

Prerequisites

• Docker installed
• A directory on your host to mount

Basic Syntax for Mounting a Directory

The -v flag lets you specify a host directory and a container directory, separated by a colon. For example:

# Mount ./data from your host to /app/data in the container
docker run --rm -v $(pwd)/data:/app/data busybox ls /app/data

This command runs ls inside the container, showing the contents of your local ./data directory as seen from /app/data in the container.

Read-Only Mounts

If you want the container to have read-only access, add :ro to the end:

# Mount as read-only
docker run --rm -v $(pwd)/config:/etc/config:ro busybox ls /etc/config

This is helpful for sharing configuration files without letting the container modify them.

Permissions and SELinux Notes

On Linux, make sure your user has permission to access the host directory. If you run into permission issues, try adjusting ownership or using sudo.

Next Steps

Try mounting different directories for development, or use named volumes for persistent data. Explore Docker Compose for more complex setups.

Good luck with your project!

Related Resources

• How to Add a Volume to an Existing Container: add volumes after creation
• Docker Persistent Storage for Databases: database volume patterns
• Docker Data Loss When Container Exits: prevent data loss
• Introduction to Docker: Volumes: volume fundamentals