dev-ops-challenges

Linux Bash Scripts (Automated Backups)

Technical Overview

In production environments, automated data backup is a critical component of disaster recovery (DR) plans. Automating these procedures using Bash scripts reduces human error, guarantees schedule consistency, and speeds up recovery times.

A typical backup automation workflow involves:

  1. Locating Source Data: Identifying the target files, folders, or databases to back up (e.g., website files under /var/www/html/).
  2. Archiving & Compression: Packing and compressing the directory to reduce storage space and network transfer times (e.g., using tar or zip).
  3. Local Staging: Saving the compressed archive in a local storage path (e.g., /backup/).
  4. Remote Transfer: Copying the staging file over a secure network channel to a dedicated backup server (using scp or rsync).
  5. Security Integration: Configuring password-less public-key SSH authentication between the servers to ensure the script executes non-interactively without stalling for user inputs.

This guide outlines the steps to configure password-less SSH between an application server and the central backup server, write a robust Bash script (ecommerce_backup.sh), and verify automated file delivery.

Infrastructure & Configuration Requirements

Step-by-Step Implementation

Step 1: Connect to the Application Server

SSH into the assigned application server from the Jump Host:

# Example for App Server 2
ssh steve@stapp02

Step 2: Configure Password-less SSH to the Backup Server

To allow the backup script to run automatically without prompting for password credentials during the file transfer step:

  1. Generate SSH Key Pair on the App Server (press Enter through all prompt defaults): 
    ssh-keygen -t rsa
  2. Copy the Public Key to the target backup server. You will be prompted to enter the backup user’s password once: 
    # Example copying to user clinton on backup server stbkp01
ssh-copy-id clinton@stbkp01
  3. Verify Connection: Test that you can SSH to the backup server without entering a password: 
    ssh clinton@stbkp01

    Expected result: Immediate terminal prompt switch to [clinton@stbkp01 ~]$ without a password challenge. Type exit to return to the App Server.

Step 3: Create Local Staging & Script Directories

Create the folders required to house the script and store the local backup files. Set appropriate ownership if necessary:

sudo mkdir -p /scripts /backup
sudo chown -R $USER:$USER /scripts /backup

Step 4: Install the Compression Utility

Ensure the zip utility package is installed on the server:

sudo yum install -y zip

Step 5: Write the Backup Script

Create the backup script file using a text editor:

vi /scripts/ecommerce_backup.sh

Paste the following script content into the file. It zips the target directory and transfers it to the remote server using scp:

#!/bin/bash

# Define variables
SOURCE_DIR="/var/www/html/ecommerce"
BACKUP_DIR="/backup"
ARCHIVE_NAME="xfusioncorp_ecommerce.zip"
BACKUP_SERVER="stbkp01"
BACKUP_USER="clinton"

# 1. Compress the website files into a local zip archive
zip -r "${BACKUP_DIR}/${ARCHIVE_NAME}" "${SOURCE_DIR}"

# 2. Transfer the archive to the remote backup server
scp "${BACKUP_DIR}/${ARCHIVE_NAME}" "${BACKUP_USER}@${BACKUP_SERVER}:${BACKUP_DIR}/"

Save and exit the file (in vi, press Esc, type :wq, and press Enter).

Step 6: Grant Execution Permissions

Make the script executable so it can be run directly:

chmod +x /scripts/ecommerce_backup.sh

Post-Deployment Verification

1. Test Run the Script

Manually execute the script to verify that it completes without warnings or prompts:

/scripts/ecommerce_backup.sh

2. Verify Local Staging Archive

Confirm that the compressed .zip archive exists in the local backup folder:

ls -lh /backup/

Expected output:

-rw-r--r-- 1 steve steve 12M Jun 27 18:20 xfusioncorp_ecommerce.zip

3. Verify Remote Transfer

SSH into the backup server and check that the file has been successfully copied into the target backup folder:

ssh clinton@stbkp01 "ls -lh /backup/"

Expected output:

-rw-r--r-- 1 clinton clinton 12M Jun 27 18:20 xfusioncorp_ecommerce.zip

Log out of the Application Server:

exit