Website Uptime Monitoring Script

This repository contains a bash script to monitor the uptime of a list of websites. The script sends email notifications if a website goes down or comes back up. It can also send summary reports of websites that are currently down.

Features

• Monitors a list of websites for uptime.
• Sends email notifications when a website goes down or comes back up.
• Can run in summary mode to send a list of all websites that are currently down.

How It Works

The script monitors the uptime of a list of websites by performing the following steps:

1. Website Status Check: The script uses curl to send an HTTP request to each website. The curl command is configured to follow redirects (-L option) and handle cookies (-c and -b options) to ensure that websites using cookies for session management are properly checked. The command retrieves the HTTP status code of the website, which indicates whether the website is up or down.

   http_code=$(curl -L -c $tempfile -b $tempfile --silent -o /dev/null --head --write-out "%{http_code}" "$url")

2. Status Comparison: The script compares the current status of each website with its previous status, stored in a temporary file. If the status has changed (e.g., from up to down or from down to up), the script prepares an email notification with the relevant information.

3. Email Notifications: The script sends email notifications to a predefined list of recipients. When a website goes down, it sends a "DOWN Alert" email with the time the website was first detected as down. When a website comes back up, it sends an "UP Alert" email with the duration of the downtime.

4. Summary Mode: In summary mode, the script does not perform uptime checks. Instead, it reads the previous status file and sends a summary email listing all websites that are currently down. This mode relies on the output from the most recent uptime checks performed in regular mode.

Requirements

• curl for making HTTP requests.
• mailx for sending emails.

Usage

Running the Script

./uptime.sh

Options

• --summary: Runs the script in summary mode, sending an email with the list of all websites that are currently down.
• --debug: Enables debug mode, printing detailed information about the script's execution.
• --help: Displays usage information.

Summary mode does not check website uptime. It only sends a summary email based on the results of the most recent uptime check. Therefore, you still need to run the script in regular mode to perform the actual uptime checks.

Example Cron Jobs

To run the script every minute:

* * * * * /path/to/this/uptime.sh
0 * * * * /path/to/this/uptime.sh --summary

Email Notifications Examples

Down Alert

Subject: 🔴 [example.com] DOWN Alert

example.com is down since January 01, 2024 12:00:00 GMT.

HTTP code: 500

Up Alert

Subject: ✅ [example.com] UP Alert

example.com is UP again at January 01, 2024 12:05:00 GMT, after 5m of downtime.

Summary

Subject: 🔴 DOWN Alert Summary

The following sites are down:

https://example.com is down since January 01, 2024 12:00:00 GMT
https://anotherexample.com is down since January 01, 2024 12:00:00 GMT

Configuration

Email Addresses

The script sends notifications to a predefined list of email addresses. To add or remove email addresses, modify the emails array in the script:

emails=("your-email@example.com")

Timezone

The script uses a specific timezone for formatting timestamps. To change the timezone, modify the timezone variable in the script:

timezone="America/Winnipeg"

Websites

The script monitors a predefined list of websites. To add or remove websites, modify the websites array in the script:

websites=(
  "https://example.com"
  "https://anotherexample.com"
)