Apache Benchmark (ab) - HTTP Server Testing Tool Guide

Table of Contents

• Overview
• Installation
• Basic Usage
• Advanced Options
• Performance Testing
• Results Analysis
• Best Practices
• Common Scenarios

Overview

Apache Benchmark (ab) is a simple but powerful command-line tool for measuring HTTP server performance. It’s particularly useful for quick load testing and server benchmarking.

Key Features

• HTTP/HTTPS testing
• Concurrent connections
• POST data support
• Custom headers
• Basic authentication
• Cookie support
• Detailed statistics
• Percentile analysis

Installation

Ubuntu (22.04/24.04)

# Install apache2-utils
sudo apt update
sudo apt install apache2-utils

macOS

# Using Homebrew
brew install apache2-utils

Basic Usage

Simple Tests

# Basic test (100 requests, 1 concurrent)
ab -n 100 http://localhost/
 
# Concurrent requests
ab -n 1000 -c 10 http://localhost/
 
# With verbosity
ab -v 2 -n 100 -c 10 http://localhost/

Basic Options

# Test with keep-alive
ab -k -n 1000 -c 10 http://localhost/
 
# Specify timeout
ab -n 1000 -c 10 -t 2 http://localhost/
 
# Display progress
ab -n 1000 -c 10 -r http://localhost/

Advanced Options

Authentication and Headers

# Basic authentication
ab -A username:password -n 100 http://localhost/
 
# Custom headers
ab -H "Accept-Encoding: gzip" -n 100 http://localhost/
 
# Multiple headers
ab -H "Authorization: Bearer token" \
   -H "Content-Type: application/json" \
   -n 100 http://localhost/

POST Requests

# POST with data
ab -p data.json -T application/json \
   -n 100 -c 10 http://localhost/api
 
# POST with inline data
ab -p - -T application/x-www-form-urlencoded \
   -n 100 "http://localhost/" <<EOF
param1=value1&param2=value2
EOF

Cookie Support

# Send cookie
ab -C "sessionId=abc123" -n 100 http://localhost/
 
# Use cookie file
ab -C cookie.txt -n 100 http://localhost/

Performance Testing

Load Testing

# Gradual load increase
ab -n 100 -c 1 http://localhost/
ab -n 100 -c 10 http://localhost/
ab -n 100 -c 50 http://localhost/
 
# Sustained load
ab -n 10000 -c 100 http://localhost/

Time-based Testing

# Run for specific duration
ab -t 60 -c 10 http://localhost/
 
# With keep-alive
ab -k -t 60 -c 10 http://localhost/

SSL Testing

# HTTPS testing
ab -n 100 -c 10 https://localhost/
 
# With SSL options
ab -n 100 -c 10 -f SSL3 https://localhost/
 
# Ignore SSL errors
ab -n 100 -c 10 -k -s 1 https://localhost/

Results Analysis

Understanding Output

Server Software:        nginx/1.18.0
Server Hostname:        localhost
Server Port:           80
 
Document Path:         /
Document Length:       1234 bytes
 
Concurrency Level:     10
Time taken for tests:  1.234 seconds
Complete requests:     1000
Failed requests:       0
Keep-Alive requests:   1000
Total transferred:     1234567 bytes
HTML transferred:      1234000 bytes
Requests per second:   810.37 [#/sec] (mean)
Time per request:      12.340 [ms] (mean)
Time per request:      1.234 [ms] (mean, across all concurrent requests)
Transfer rate:         975.61 [Kbytes/sec] received

Important Metrics

# High-level performance check
ab -n 1000 -c 10 -g results.tsv http://localhost/
 
# Analyze percentiles
ab -n 1000 -c 10 -e results.csv http://localhost/
 
# Detailed verbosity
ab -v 3 -n 100 -c 10 http://localhost/

Best Practices

Testing Guidelines

# Warm-up run
ab -n 100 -c 1 http://localhost/
 
# Progressive load testing
for c in 1 10 50 100; do
    echo "Testing with $c concurrent users"
    ab -n 1000 -c $c http://localhost/
    sleep 5
done

Resource Monitoring

# Monitor system during test
vmstat 1
 
# Watch network connections
watch -n1 'netstat -an | grep ESTABLISHED | wc -l'
 
# Monitor server load
top -b -n 1

Common Scenarios

API Testing

# GET request with headers
ab -H "Authorization: Bearer token" \
   -H "Accept: application/json" \
   -n 1000 -c 10 http://localhost/api
 
# POST request
ab -p payload.json \
   -T application/json \
   -H "Authorization: Bearer token" \
   -n 1000 -c 10 http://localhost/api

Web Application Testing

# Test with cookies
ab -C "session=123456" \
   -n 1000 -c 10 http://localhost/
 
# Form submission
ab -p form.txt \
   -T application/x-www-form-urlencoded \
   -n 100 -c 10 http://localhost/submit

Quick Reference

Essential Commands

# Basic test
ab -n 100 -c 10 http://localhost/
 
# Keep-alive test
ab -k -n 100 -c 10 http://localhost/
 
# POST test
ab -p data.json -T application/json -n 100 http://localhost/
 
# HTTPS test
ab -n 100 -c 10 https://localhost/

Common Options

-n    # Number of requests
-c    # Concurrent requests
-k    # Keep-alive
-p    # POST file
-T    # Content-type
-H    # Custom header
-A    # Authentication
-C    # Cookie
-v    # Verbosity level

Example Configurations

Basic Load Test

#!/bin/bash
# Progressive load test
URLS="
http://localhost/page1
http://localhost/page2
"
 
for url in $URLS; do
    echo "Testing $url"
    for c in 10 50 100; do
        echo "Concurrency: $c"
        ab -n 1000 -c $c -r "$url"
        sleep 2
    done
done

API Performance Test

#!/bin/bash
# API endpoints test
ab -n 1000 -c 10 \
   -H "Authorization: Bearer token" \
   -H "Content-Type: application/json" \
   -T application/json \
   -p payload.json \
   http://localhost/api/endpoint

---

Remember:

• Start with lower concurrency
• Monitor server resources
• Use appropriate timeouts
• Consider keep-alive for real-world scenarios
• Document test conditions
• Analyze all metrics

For detailed information, consult the ab man page (man ab).