Working with Docker Volumes

A Hands-on Lab Guide

Table of Contents

1. Introduction

2. Solution Overview

3. Step-by-Step Implementation

4. Command Reference

5. Conclusion

1. Introduction

This guide demonstrates how to create a Docker container using an NGINX base image with two persistent volumes:

Volume 1: Stores HTML files (/usr/share/nginx/html)

Volume 2: Stores NGINX logs (/var/log/nginx)

Persistent volumes ensure data survives container restarts or deletions. 

2. Solution Overview

We will:

Create a Dockerfile defining the NGINX image with volumes

Build and tag the Docker image

Create named volumes for persistence

Run a container with volume mount

Test by modifying the default webpage

3. Step-by-Step Implementation

Step 1: Create a Dockerfile

A. Gain root privileges:

bash

sudo su -

Switches to admin user to avoid permission issues

B. Create and edit the Dockerfile:

bash

vi Dockerfile

Opens Vim editor to create the configuration file

C. Add these instructions:

FROM nginx

VOLUME /usr/share/nginx/html

VOLUME /var/log/nginx

WORKDIR /usr/share/nginx/html

NOTE

• FROM: Uses official NGINX image as base

• VOLUME: Declares persistent storage paths

• WORKDIR: Sets default container working directory

D. Save and exit (:wq in Vim)

Step 2: Build the Docker Image

bash

docker build -t la/nextgen:latest -f Dockerfile .

NOTE

- -t: Tags the image (name:version)

- -f: Specifies Dockerfile name

- ‘:’ Uses current directory as build context

Step 3: Create Docker Volumes

For HTML content:

bash

docker volume create nginx-code

For server logs:

bash

docker volume create nginx-logs

NOTE

This creates named volumes managed by Docker

Step 4: Run the Container

bash

docker run -d --name=nextgen-dev -p 80:80 --mount source=nginx-code,target=/usr/share/nginx/html --mount source=nginx-logs,target=/var/log/nginx la/nextgen:latest

NOTE

- -d: Runs in background

- --name: Assigns container name

- -p: Maps host:container ports

- --mount: Attaches volumes to container paths

Verify it's running:

`bash

docker ps

Step 5: Test the Setup

a. Locate the volume data:

bash

cd /var/lib/docker/volumes/nginx-code/_data/

Docker stores volume contents here by default

b. Edit the webpage:

bash

vi index.html

Add:

html

<p>ANY WELCOME MESSAGE! </p>

c. Access http: //localhost` to see your changes.

4. Command Reference

6. Conclusion

You've now:

- Created a Docker image with persistent storage

- Learned essential Docker commands for volume management

- Verified data persists across container lifecycles