Dhanian 🗯️@e_opore
🐳 Day 6/30 — #Docker
Containers are designed to be temporary. If a container is removed, any data stored inside it is lost. Docker Volumes solve this problem by providing persistent storage that exists independently of containers.
Docker Volumes – Persistent Storage and Data Management
Docker volumes allow applications to store and manage data safely, even when containers are stopped, restarted, or deleted.
Volumes are the recommended way to persist data in Docker because they are managed by Docker and optimized for performance.
Why Docker Volumes?
Without volumes:
→ Container is deleted
→ Application data is lost
With volumes:
→ Data survives container removal
→ Multiple containers can access shared data (when appropriate)
→ Easy backup and migration
→ Better performance than storing data inside containers
Volumes are commonly used for databases, file uploads, logs, and application data.
Creating a Volume
Create a new volume:
→ docker volume create postgres-data
List available volumes:
→ docker volume ls
Inspect a volume:
→ docker volume inspect postgres-data
Docker stores the volume in a managed location on the host machine.
Using a Volume
Attach a volume when running a container:
→ docker run -d
→ --name postgres-db
→ -v postgres-data:/var/lib/postgresql/data
→ postgres
The -v option mounts the volume into the container.
Any data written to /var/lib/postgresql/data is stored persistently.
Viewing Volume Usage
Inspect running containers:
→ docker ps
View mounted volumes:
→ docker inspect postgres-db
This shows where volumes are attached inside the container.
Removing Volumes
Remove an unused volume:
→ docker volume rm postgres-data
Remove unused volumes:
→ docker volume prune
Be careful—removing a volume permanently deletes its stored data.
Volumes vs Bind Mounts
Docker Volumes
→ Managed by Docker
→ Portable across environments
→ Better performance
→ Recommended for production
Bind Mounts
→ Maps a host directory into the container
→ Useful during development
→ Allows live editing of project files
→ Depends on the host filesystem structure
For databases and production applications, Docker volumes are usually the better choice.
Project
Run PostgreSQL with persistent data.
Complete the following tasks:
→ Create a Docker volume:
→ docker volume create postgres-data
→ Run a PostgreSQL container using the volume:
→ docker run -d
→ --name postgres-db
→ -e POSTGRES_PASSWORD=mysecretpassword
→ -v postgres-data:/var/lib/postgresql/data
→ -p 5432:5432
→ postgres
→ Verify the container is running:
→ docker ps
→ Stop the container:
→ docker stop postgres-db
→ Start it again:
→ docker start postgres-db
→ Confirm your database data is still available
The PostgreSQL data remains intact because it is stored in the Docker volume rather than inside the container.
Why This Matters:
→ Persist application and database data
→ Prevent data loss when containers are removed
→ Simplify backups and migrations
→ Build reliable production deployments
→ Learn one of Docker's most important storage features
Understanding Docker volumes is essential for running databases, stateful applications, and production workloads that require reliable persistent storage.
🐳 Grab Docker Ebook: codewithdhanian.gumroad.com/l/vnqwjy
#Docker #DockerTutorial #DockerVolumes #PostgreSQL #Containers #Databases #DevOps #CloudComputing #SoftwareEngineering #100DaysOfCode
