feat: cron job for pruning docker images

docker-prune-cron/README.md

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+# Docker Image Pruning Cron Job for Dev server
+
+This README provides instructions for setting up a cron job to regularly prune old Docker images on a Dev server. Pruning Docker images helps to manage disk space effectively by removing unused images.
+
+## Prerequisites
+
+- SSH access to the Dev server.
+
+## Steps to Set Up the Cron Job
+
+### 1. Access the Dev Server
+
+SSH into your Dev server:
+
+```sh
+ssh [email protected]
+```
+
+
+### 2. Set Up the Cron Job
+
+Edit the cron table to schedule the pruning job every 4 hours.
+
+Open the crontab for editing:
+
+```sh
+crontab -e
+```
+
+Add the following line to schedule the job:
+
+```
+0 */4 * * * /home/azureuser/prune_docker_images.sh
+```
+
+### 3. Verify the Cron Job
+
+List the current cron jobs to ensure your job is added:
+
+```sh
+crontab -l
+```
+You can also check the logged output:
+
+```sh
+
+cat docker_prune_cron.log
+```
+
+## Troubleshooting
+
+Check cron service status to ensure the cron service is running:
+
+```sh
+systemctl status cron
+```
+
+#### Check Syslog for Errors
+
+If the cron job doesn’t seem to run, check the syslog for cron errors:
+
+```sh
+grep CRON /var/log/syslog
+```

docker-prune-cron/docker_prune_cron.sh

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+#!/bin/bash
+
+set -o errexit
+set -o nounset
+
+LOGFILE="$HOME/docker_prune_cron.log"
+
+current_date=$(date -Iseconds)
+
+{
+  echo "Starting Docker system prune at $current_date"
+  sudo docker system prune --volumes --force
+  echo "Completed at $(date -Iseconds)"
+} >> "$LOGFILE" 2>&1