Leveraging NFS Filesystem as Volumes in Docker: A Comprehensive Guide

As a DevOps engineer, I’ve had my fair share of experiences with containerized environments and the challenges that come with managing data persistence. One of the most significant problems I’ve faced is ensuring that data generated by Docker containers is persisted even when the container is stopped or deleted. That’s when I discovered the power of leveraging the Network File System (NFS) as volumes in Docker.

It all started when I was working on a complex, multi-container application that required efficient data management. I knew that Docker volumes were the way to go, but I needed a solution that would provide centralized storage management, scalability, and seamless file sharing across different containers and hosts. That’s when I turned to NFS.

Let’s understand what is a Docker Volume

In containerized environments, the persistent storage of data generated by Docker containers is enabled by Docker volumes. Within the Docker context, a volume is considered a specially designated directory within one or more containers that exists outside the typical Union File System. This means that data stored in volumes is persisted even when the container is stopped or deleted, making volumes indispensable for scenarios where data persistence is required.

What does Network File System mean ?

NFS, also known as Network File System, is a distributed file system protocol that allows files and directories stored on remote servers to be accessed by clients as if they were local. Operated over a network, NFS provides a shared file system that can be accessed by multiple clients simultaneously. Benefits such as centralized storage management, improved data availability, and seamless file sharing across heterogeneous environments are offered by NFS.

Install these Before proceeding further

• NFS server installed
• Docker and Docker-compose installed

My journey began with setting up an NFS server. I created a directory at /srv/nfs where the NFS server would store the shared files. I then added an entry to the /etc/exports file, specifying that the directory /srv/nfs could be accessed by any client with read-write permissions. I also set the permissions for the NFS directory to 755, ensuring that the owner had full read-write-execute permissions, while others had read and execute permissions.

Use this Script to things I just mentioned above

#!/bin/bash

# Step 1: Create a directory for NFS
NFS_DIR="/srv/nfs"
echo "Creating NFS directory at $NFS_DIR..."
sudo mkdir -p $NFS_DIR

# Step 2: Add export entry to /etc/exports
EXPORTS_ENTRY="$NFS_DIR *(rw,sync,no_subtree_check)"
echo "Adding the following entry to /etc/exports:"
echo "$EXPORTS_ENTRY"
echo "$EXPORTS_ENTRY" | sudo tee -a /etc/exports

# Step 3: Grant necessary permissions to the NFS directory
echo "Setting permissions for $NFS_DIR..."
sudo chmod 755 -R $NFS_DIR

# Step 4: Restart NFS service to apply changes
echo "Restarting NFS service..."
sudo exportfs -ra
sudo systemctl restart nfs-kernel-server

echo "NFS server setup complete!"

Run the script using the command

chmod +x setup_nfs.sh

sudo ./setup_nfs.sh

With the NFS server setup complete, I created an NFS Docker volume using the docker volume create command. I specified the NFS server’s IP address, the mount point, and the device path.

Run these command to create a docker volume with nfs configuration

docker volume create --driver local --opt type=nfs --opt o=addr=<ip-address-of-nfs-server>,rw --opt device=:/srv/nfs  nfs-volume

Output:

To verify that the volume was created successfully, I used this command.

docker volume ls

It would show like this

Mounting NFS in a Container: A Moment of Truth

Next, I mounted the NFS volume in a container using the docker run command. I specified the NFS volume and the mount point in the –mount section.

Output:

To verify, we can use the following command with docker exec:

docker exec -it nfs_mounted_node_container sh

mount | grep /opt

It will display something similar to this

Docker Compose and NFS: Expanding Horizons

But the journey didn’t stop there. I needed to ensure that my NFS volumes could be easily managed across multiple containers. This is where Docker Compose came into play. By creating a docker-compose.yml file, I could define services that utilized NFS volumes:

nano docker-compose.yml

Write the following contents inside the Docker Compose file.

version: '3.8'
services:
  mongo:
    image: mongo
    container_name: nfs_mounted_container
    volumes:
    - mongo_data:/data/db
volumes:
  mongo_data:
    driver_opts:
    type: nfs4
    o: addr=<ip-address-of-nfs-server>,rw
    device: ":/srv/nfs"

Reflections: The Benefits of Using NFS with Docker

Looking back at this, the benefits of using NFS for persistent volumes in Docker are clear:

1. Centralized Storage Management: NFS provides a centralized storage solution where files and directories are stored on remote servers. This centralized approach simplifies storage management as administrators can manage and maintain data from a single location.
2. Scalability: NFS allows for seamless scaling of storage capacity by adding more NFS servers or expanding existing ones. This scalability ensures that Docker containers have access to sufficient storage resources as application demands grow.
3. Improved Data Availability: With NFS, data stored on remote servers is readily available to Docker containers across the network. This improved availability ensures that applications have continuous access to critical data, minimizing downtime and improving overall reliability.
4. Seamless File Sharing: NFS enables seamless file sharing across multiple Docker containers and hosts. Containers can mount NFS volumes and access shared files and directories, facilitating collaboration and data sharing among different parts of the application.
5. Data Consistency and Reliability: NFS ensures data consistency and reliability by maintaining a single version of truth for files and directories stored on remote servers. This reliability ensures that Docker containers retrieve accurate and up-to-date information from NFS volumes, enhancing application stability.But, using this setup for database containers will be a bad idea.
6. Compatibility and Interoperability: NFS is supported by a wide range of operating systems and platforms, making it highly compatible and interoperable with various Docker environments. This compatibility allows Docker containers running on different systems to access NFS volumes seamlessly.

Conclusion

In short, using NFS with Docker offers many benefits, it helps manage storage in one place, scales easily, ensures data is always available, allows easy file sharing, maintains data accuracy, and works well with different systems. Overall, it boosts application performance and reliability by handling data efficiently across different setups. This makes it a strong choice for managing data effectively in modern applications.

Question

Have you tried using NFS with Docker yet? If you have, what did you like, and what didn’t you like?