Are you tired of losing your precious data every time you restart your Docker container? Do you find yourself scratching your head, wondering why your Docker volume is cleared on every restart via Docker-Compose on Ubuntu? Fear not, dear reader, for you have stumbled upon the right article! In this comprehensive guide, we’ll delve into the world of Docker volumes, explore the reasons behind this phenomenon, and provide you with step-by-step instructions to overcome it.
What is a Docker Volume?
A Docker volume is a directory that is shared between the host machine and a Docker container. It allows you to persist data even after the container is deleted or restarted. Docker volumes are essential when working with databases, as they ensure that your valuable data is not lost during container recreation.
Why is Docker Volume Cleared on Every Restart via Docker-Compose on Ubuntu?
There are several reasons why your Docker volume might be cleared on every restart via Docker-Compose on Ubuntu:
- volumes are not persisted by default: When you create a Docker container, the volume is not persisted by default. This means that when the container is restarted, the volume is recreated, and all data is lost.
- docker-compose down removes volumes: When you run
docker-compose down, Docker-Compose removes all containers, networks, and volumes. This means that your data is deleted, and the volume is cleared. - Ubuntu’s Docker configuration: Ubuntu’s Docker configuration might be set up to remove volumes on restart. This can be due to the way Docker is installed or configured on your system.
How to Persist Docker Volume on Ubuntu
Now that we’ve explored the reasons behind the issue, let’s dive into the solutions! Here are step-by-step instructions to persist your Docker volume on Ubuntu:
Method 1: Use Docker-Compose Volumes
docker-compose.yml file, add the volumes keyword to specify a persistent volume:
version: '3'
services:
db:
image: postgres
volumes:
- db-data:/var/lib/postgresql/data
volumes:
db-data:
driver: local
driver_opts:
type: none
device: ${PWD}/db-data
o: bind
In this example, we’re using a named volume db-data to persist data in the /var/lib/postgresql/data directory. The driver_opts section specifies the location of the volume on the host machine.
Method 2: Use Docker Volume Command
Instead of using Docker-Compose, you can create a Docker volume using the docker volume command:
docker volume create --driver local \
--opt type=none \
--opt device=$(pwd)/db-data \
--opt o=bind \
db-data
Then, in your docker-compose.yml file, reference the volume:
version: '3'
services:
db:
image: postgres
volumes:
- db-data:/var/lib/postgresql/data
Method 3: Use Ubuntu Disk Configuration
On Ubuntu, you can configure the Docker disk usage to persist data across restarts. Edit the /etc/docker/daemon.json file:
sudo nano /etc/docker/daemon.json
Add the following configuration:
{
"graph": "/mnt/docker"
}
Restart the Docker service:
sudo systemctl restart docker
This method persists all Docker data, including volumes, across restarts.
Troubleshooting Common Issues
If you’re still experiencing issues with your Docker volume being cleared on every restart, here are some common issues to check:
- permissions issues: Ensure that the user running the Docker service has the necessary permissions to access the volume.
- volume path issues: Verify that the volume path is correct and that the directory exists on the host machine.
- docker-compose version issues: Make sure you’re using the latest version of Docker-Compose.
Conclusion
Persisting Docker volumes on Ubuntu can be a challenge, but with the right approaches, you can overcome it. By using Docker-Compose volumes, Docker volume commands, or Ubuntu disk configuration, you can ensure that your data is safe across restarts. Remember to troubleshoot common issues, and you’ll be well on your way to Docker volume persistence.
| Method | Description |
|---|---|
| Method 1: Use Docker-Compose Volumes | Specify a persistent volume in docker-compose.yml file |
| Method 2: Use Docker Volume Command | Create a Docker volume using the docker volume command |
| Method 3: Use Ubuntu Disk Configuration | Configure Docker disk usage to persist data across restarts |
Bookmark this article as your go-to guide for persisting Docker volumes on Ubuntu. With these methods and troubleshooting tips, you’ll be able to overcome the mystery of the cleared Docker volume and ensure data persistence across restarts.
Frequently Asked Question
Got stuck with Docker volumes disappearing on every restart? You’re not alone! Here are some frequently asked questions and answers to help you troubleshoot the issue on Ubuntu.
Why does my Docker volume get cleared on every restart?
By default, Docker volumes are ephemeral, meaning they are deleted when the container is removed or restarted. To persist data, you need to use a named volume or a bind mount.
How can I persist data in a Docker volume using docker-compose?
In your docker-compose file, add a volume section with a named volume, like `volumes: myvol:/path/to/data`. This will create a persistent volume that survives container restarts.
What’s the difference between a named volume and a bind mount?
A named volume is a Docker-managed directory that persists data across container restarts. A bind mount, on the other hand, mounts a host machine directory to a container directory, allowing you to access files on the host machine.
Can I use a bind mount to persist data in a Docker volume?
Yes, you can use a bind mount to persist data in a Docker volume. For example, `volumes: ./data:/path/to/container/data` will mount the `./data` directory on the host machine to the container’s `/path/to/container/data` directory.
How can I troubleshoot Docker volume issues on Ubuntu?
Check the Docker volume logs with `docker-compose logs -f`, verify volume permissions, and inspect the volume configuration with `docker volume inspect
