One of Docker’s most powerful features is the ability to mount a directory from your host machine into a container. This allows you to:
- Share code or configuration files between host and container
- Persist container data on the host
- Live-edit files during development
In this blog, you’ll learn how to mount a host directory in a Docker container using the -v or --mount flag, when to use each, and common pitfalls to avoid.
🧠 Why Mount a Directory?
Mounting host directories into containers lets you:
- Avoid rebuilding images for every file change
- Access logs or output files generated by containers
- Use local configuration files (e.g.,
.env,.yaml) directly - Store persistent data like databases outside the container
✅ Syntax 1: Use -v (Volume Mount)
docker run -v /path/on/host:/path/in/container my-image
Example:
docker run -v $(pwd)/app:/usr/src/app node:18
- The code from your current directory (
./app) will be mounted to/usr/src/appin the container. - Changes in either location are reflected immediately.
✅ Syntax 2: Use --mount (More Explicit)
docker run \
--mount type=bind,source=/path/on/host,target=/path/in/container \
my-image
Example:
docker run \
--mount type=bind,source="$(pwd)/data",target=/app/data \
python:3.11
The --mount syntax is more verbose but easier to read and manage in complex scripts or Compose files.
📌 Difference Between -v and --mount
| Feature | -v or --volume | --mount |
|---|---|---|
| Simpler syntax | ✅ | ❌ |
| Better readability | ❌ | ✅ |
| Recommended for | Quick CLI usage | Scripts & production setup |
🛠️ Use with Docker Compose
In docker-compose.yml, you can define volume mounts like this:
services:
web:
image: nginx
volumes:
- ./html:/usr/share/nginx/html
This will mount the local html directory into the container’s web root.
⚠️ Permissions & Path Tips
- Make sure the host directory exists. Docker won’t auto-create nested folders.
- On Windows or macOS, paths must be absolute or properly escaped.
- Some base images may need
chownorchmodto access mounted directories.
📝 Conclusion
Mounting a host directory into a Docker container is a must-know technique for development, debugging, and data persistence. Whether you use -v or --mount, this simple feature can dramatically improve your container workflows.
🔑 Quick Summary
| Task | Command Example |
|---|---|
Mount with -v | docker run -v /host:/container my-image |
Mount with --mount | docker run --mount type=bind,source=/h,target=/c |
| In Docker Compose | volumes: - ./local:/container/path |