A standalone tool to transform a Varnish output file into a simple diagram sequence.
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kint @ b091715


Varnishlog Parser

Software License Maintenance

A standalone tool to transform a Varnish output file into a simple diagram sequence.



  • Varnish 4.1
  • PHP 5 (tested with PHP 5.6) or PHP 7.0
  • cURL (sudo apt-get install php5-curl or php-curl)
  • Internet access to websequencediagrams.com (generated diagram)

Installation and usage

First, you need to generate a varnishlog output.

  • Log in your Varnish server
  • Execute this command: varnishlog -g raw > /tmp/output.log
  • Navigate on your website for few seconds, then kill varnishlog with Ctrl+C
  • Get the output file on your computer

Then, install this tool:

  • git clone https://github.com/TOMHTML/varnishlog-parser.git varnishlog-parser
  • cd varnishlog-parser
  • git submodule update --init, to download the Kint library

Finally, execute the web client as a standalone tool:

  • php -S client.php
  • Go to
  • Enter the local path to your output.log file in the first form, or upload the file
  • Have fun!

Feel free to install Varnishlog Parser on a private web server like Apache or Nginx.


Feel free to submit pull requests. The code is documented, but the logic is still complex (because Varnishlog is).

Known bugs

This is a week-end project, home alone, so it's not fully tested and there is obviously a handful of hidden bugs. Nevertheless, main unusual use cases have been tested (ESI, restarts, truncated file, synth responses, custom vmods, background fetches...).

  • In some edge cases, transactions order might not be fully respected.
  • Very big files might cause timeout errors. Increase the value of max_execution_time and upload_max_filesize in php.ini to fix that.


  • Set apart different clients (by IP)
  • Set apart different backends (by backend name or IP)
  • Parse and graph cookies
  • Add timestamps
  • Complete documentation


See the LICENSE file for license rights and limitations (MIT).


Special thanks to :