http_timing_breakdown.sh

#!/usr/bin/env bash

set -euo pipefail

# http_timing_breakdown.sh
# Measures HTTP timing phases (DNS/connect/TLS/TTFB/total) over repeated requests.

usage() {
  cat <<'EOF'
Usage: ./http_timing_breakdown.sh --url URL [options]

Options:
  --url URL              Target URL (required)
  --attempts N           Number of requests (default: 5)
  --timeout SEC          Per-request timeout (default: 10)
  --insecure             Allow insecure TLS certs (curl -k)
  --warn-total MS        Warn threshold for total request time in ms (default: 1500)
  --warn-ttfb MS         Warn threshold for time-to-first-byte in ms (default: 800)
  --strict               Exit non-zero if thresholds are exceeded
  -h, --help             Show help

Exit codes:
  0 = no threshold warnings (or warnings in non-strict mode)
  2 = threshold warning in strict mode
EOF
}

URL=""
ATTEMPTS=5
TIMEOUT=10
INSECURE=false
WARN_TOTAL_MS=1500
WARN_TTFB_MS=800
STRICT=false

while [[ $# -gt 0 ]]; do
  case "$1" in
    --url) URL="$2"; shift 2 ;;
    --attempts) ATTEMPTS="$2"; shift 2 ;;
    --timeout) TIMEOUT="$2"; shift 2 ;;
    --insecure) INSECURE=true; shift ;;
    --warn-total) WARN_TOTAL_MS="$2"; shift 2 ;;
    --warn-ttfb) WARN_TTFB_MS="$2"; shift 2 ;;
    --strict) STRICT=true; shift ;;
    -h|--help) usage; exit 0 ;;
    *) echo "Unknown option: $1"; usage; exit 1 ;;
  esac
done

if [[ -z "$URL" ]]; then
  echo "--url is required"
  usage
  exit 1
fi

if ! command -v curl >/dev/null 2>&1; then
  echo "curl command not found"
  exit 1
fi

echo "HTTP timing breakdown timestamp: $(date -Iseconds)"
echo "url=$URL attempts=$ATTEMPTS timeout=${TIMEOUT}s strict_mode=$STRICT"
echo "warn_total_ms=$WARN_TOTAL_MS warn_ttfb_ms=$WARN_TTFB_MS"
echo

curl_insecure_flag=()
if [[ "$INSECURE" == true ]]; then
  curl_insecure_flag=("-k")
fi

echo "attempt,status,dns_ms,connect_ms,tls_ms,ttfb_ms,total_ms"

warn_count=0
success_count=0
fail_count=0

total_ms_values=()
ttfb_ms_values=()

for ((i=1; i<=ATTEMPTS; i++)); do
  line=$(curl -sS -o /dev/null \
    --max-time "$TIMEOUT" \
    "${curl_insecure_flag[@]}" \
    -w "%{http_code},%{time_namelookup},%{time_connect},%{time_appconnect},%{time_starttransfer},%{time_total}" \
    "$URL" 2>/dev/null || true)

  if [[ -z "$line" ]]; then
    echo "$i,000,NA,NA,NA,NA,NA"
    ((fail_count+=1))
    continue
  fi

  IFS=',' read -r status dns_s connect_s tls_s ttfb_s total_s <<< "$line"

  dns_ms=$(awk -v n="$dns_s" 'BEGIN {printf "%.0f", n*1000}')
  connect_ms=$(awk -v n="$connect_s" 'BEGIN {printf "%.0f", n*1000}')
  tls_ms=$(awk -v n="$tls_s" 'BEGIN {printf "%.0f", n*1000}')
  ttfb_ms=$(awk -v n="$ttfb_s" 'BEGIN {printf "%.0f", n*1000}')
  total_ms=$(awk -v n="$total_s" 'BEGIN {printf "%.0f", n*1000}')

  echo "$i,$status,$dns_ms,$connect_ms,$tls_ms,$ttfb_ms,$total_ms"

  if [[ "$status" == "000" ]]; then
    ((fail_count+=1))
    continue
  fi

  ((success_count+=1))
  total_ms_values+=("$total_ms")
  ttfb_ms_values+=("$ttfb_ms")

  if [[ "$total_ms" -gt "$WARN_TOTAL_MS" || "$ttfb_ms" -gt "$WARN_TTFB_MS" ]]; then
    ((warn_count+=1))
  fi
done

echo
if [[ "$success_count" -gt 0 ]]; then
  total_stats=$(printf '%s\n' "${total_ms_values[@]}" | awk '
    NR==1{min=$1;max=$1;sum=$1;next}
    {if($1<min)min=$1; if($1>max)max=$1; sum+=$1}
    END{avg=sum/NR; printf "%d %.2f %d", min, avg, max}
  ')
  ttfb_stats=$(printf '%s\n' "${ttfb_ms_values[@]}" | awk '
    NR==1{min=$1;max=$1;sum=$1;next}
    {if($1<min)min=$1; if($1>max)max=$1; sum+=$1}
    END{avg=sum/NR; printf "%d %.2f %d", min, avg, max}
  ')

  total_min=$(printf '%s' "$total_stats" | awk '{print $1}')
  total_avg=$(printf '%s' "$total_stats" | awk '{print $2}')
  total_max=$(printf '%s' "$total_stats" | awk '{print $3}')

  ttfb_min=$(printf '%s' "$ttfb_stats" | awk '{print $1}')
  ttfb_avg=$(printf '%s' "$ttfb_stats" | awk '{print $2}')
  ttfb_max=$(printf '%s' "$ttfb_stats" | awk '{print $3}')

  echo "Summary: success=$success_count fail=$fail_count warn=$warn_count total_ms(min/avg/max)=${total_min}/${total_avg}/${total_max} ttfb_ms(min/avg/max)=${ttfb_min}/${ttfb_avg}/${ttfb_max}"
else
  echo "Summary: success=0 fail=$fail_count warn=$warn_count"
fi

if [[ "$STRICT" == true && "$warn_count" -gt 0 ]]; then
  exit 2
fi

exit 0