compute load time stats for web page

loadtime_webpage_stats.py

import os
import sys
import json
import pprint
import argparse
import subprocess

"""
Reference: https://blog.cloudflare.com/a-question-of-timing/

Usage: 
    single url:
        $> python3 ttfb.py -u www.zasag.mn
        $> {'proctime_server': 0.266721,
           'tcp_handshake': 0.421435,
           'time_appconnect': 1.302903,
           'time_connect': 0.423711,
           'time_namelookup': 0.002276,
           'time_starttransfer': 1.991059,
           'ttfb': 0.688156}
     single or multiple urls:
         $> python3 ttfb.py -U www.zasag.mn
         $> {'proctime_server': 0.266721,
            'tcp_handshake': 0.421435,
            'time_appconnect': 1.302903,
            'time_connect': 0.423711,
            'time_namelookup': 0.002276,
            'time_starttransfer': 1.991059,
            'ttfb': 0.688156}
         $> python3 ttfb.py -U www.zasag.mn www.zasag.mn
            {'proctime_server': 0.3054720000000001,
            'tcp_handshake': 0.41525,
            'time_appconnect': 1.270451,
            'time_connect': 0.417553,
            'time_namelookup': 0.002303,
            'time_starttransfer': 1.991173,
            'ttfb': 0.7207220000000001,
            'url': 'www.zasag.mn'}
            {'proctime_server': 0.30917799999999995,
            'tcp_handshake': 0.400841,
            'time_appconnect': 1.295195,
            'time_connect': 0.403332,
            'time_namelookup': 0.002491,
            'time_starttransfer': 2.005214,
            'ttfb': 0.710019,
            'url': 'www.zasag.mn'}
    multiple urls from file:
         $> cat urls.txt | xargs python3 ttfb.py -U
            {'proctime_server': 0.3054720000000001,
            'tcp_handshake': 0.41525,
            'time_appconnect': 1.270451,
            'time_connect': 0.417553,
            'time_namelookup': 0.002303,
            'time_starttransfer': 1.991173,
            'ttfb': 0.7207220000000001,
            'url': 'www.zasag.mn'}
            {'proctime_server': 0.30917799999999995,
            'tcp_handshake': 0.400841,
            'time_appconnect': 1.295195,
            'time_connect': 0.403332,
            'time_namelookup': 0.002491,
            'time_starttransfer': 2.005214,
            'ttfb': 0.710019,
            'url': 'www.zasag.mn'}
"""

parser = argparse.ArgumentParser(
    description="compute Time To First Byte (TTFB) for a given page"
)
parser.add_argument("-u", "--url", type=str, help="url to compute TTFB")
parser.add_argument("-U", "--urls", nargs="+", type=str, help="urls to compute TTFB")
args = parser.parse_args()

if args.url:
    urls = [args.url]
elif args.urls:
    urls = args.urls
else:
    os.system("python3 ttfb.py -h")
    sys.exit(1)

for url in urls:
    result_raw = subprocess.run(
        [
            "curl",
            "--no-sessionid",
            "-w",
            '{"time_appconnect": %{time_appconnect}, '
            '"time_starttransfer": %{time_starttransfer}, '
            '"time_namelookup": %{time_namelookup}, '
            '"time_connect": %{time_connect}}',
            "-H 'Cache-Control: no-cache'",
            "-so",
            "/dev/null",
            url,
        ],
        capture_output=True,
        text=True,
    )
    result_dict = json.loads(result_raw.stdout)
    result_dict["ttfb"] = (
        result_dict["time_starttransfer"] - result_dict["time_appconnect"]
    )
    result_dict["tcp_handshake"] = (
        result_dict["time_connect"] - result_dict["time_namelookup"]
    )
    result_dict["proctime_server"] = result_dict["ttfb"] - result_dict["tcp_handshake"]
    result_dict["url"] = url

    pprint.pprint(result_dict)