HTTP Performance Metrics Script

Custom Commands
1

1. Introduction

Monitoring the performance of web endpoints is essential to ensure optimal user experience.
This Bash script collects detailed HTTP timing metrics for a given URL, allowing network engineers to identify potential bottlenecks in the web request lifecycle.

Example Use Cases:

  • Measure Time To First Byte (TTFB) to evaluate server responsiveness
  • Monitor DNS lookup, connection, and SSL handshake times
  • Track total page load performance for web monitoring

2. Overview of the Script

This Bash script:

  1. Accepts a target URL (defaulting to https://example.com if none is provided)
  2. Uses curl to retrieve HTTP timing metrics
  3. Outputs key measurements including:
    • DNS lookup time
    • TCP connect time
    • SSL handshake time
    • Time to first byte (TTFB)
    • Total load time

Prerequisites:

  • Linux-based NetBeez agent
  • Bash shell

Expected Output:

  • Metrics reported in seconds with decimal precision for easy monitoring

3. Script Code

#!/usr/bin/env bash

# URL to measure (default if not provided)
URL="${1:-https://example.com}"

# Use curl to get timing metrics
read -r namelookup connect appconnect starttransfer total < <(
  curl -o /dev/null -s -w "%{time_namelookup} %{time_connect} %{time_appconnect} %{time_starttransfer} %{time_total}\n" "$URL"
)

# Print results in a format compatible with NetBeez metrics
echo "dns_lookup_time=$namelookup"
echo "connect_time=$connect"
echo "ssl_handshake_time=$appconnect"
echo "ttfb=$starttransfer"
echo "total_load_time=$total"

4. Sample Output

dns_lookup_time=0.012
connect_time=0.034
ssl_handshake_time=0.056
ttfb=0.123
total_load_time=0.245

5. Closing Remarks

This script provides a quick way to monitor HTTP performance metrics from a NetBeez agent, enabling you to pinpoint slow components in the request lifecycle.

Extensions you could try:

  • Automate testing multiple URLs and log metrics over time

  • Alert if any metric exceeds a threshold

  • Integrate with dashboards for real-time web performance monitoring

Share your enhancements in the comments so the community can benefit!