A Thor library which easily converts an HTTP Archive (HAR) file into a siege URLs file.
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Hardy is a Thor library which easily converts an HTTP Archive (HAR) file into a siege URLs file.

What does that mean for you? Well, it means that it's now a trivial task to generate load testing scripts for your HTTP(S) web applications and determine exactly how many concurrent, active, hammering-away-on-your-systems users your application and infrastructure can fully support.

Stop guessing and find out! It's easy!!


Add this line to your application's Gemfile (probably not in the default group, but more likely in a :test or :development group):

gem 'hardy'

And then execute:

$ bundle

Or install it yourself as:

$ gem install hardy

Generating HAR files

Creating a HAR file is simple:

  1. Open Chrome,
  2. Open the Chrome Developer Tools panel (cmd-shift-i on a Mac),
  3. With the tools panel open, navigate to the site you want to test,
  4. Click the Preserve Log upon Navigation button on the Network tab of the tools panel (otherwise, your Network tab will be cleared with each page view),
  5. Click around the site! Act like the user you want to simulate. Meaning, click links, post forms, change pages, sign in, sign out. Whatever you do here will be recreated by your load test users, so try to do things that will generate interesting test metrics.
  6. Right-click in the Network panel and click "Save as HAR with Content"

You now have a HAR file to source for load testing! 🍺

Installing siege

Note: If you are planning on testing a site which uses a JSON interface, you'll want to read the Enabling JSON support in siege section further down this README.

On a Mac, you can install siege with homebrew:

$ brew install siege

On Ubuntu:

$ apt-get install siege

Installing from source:

$ curl http://www.joedog.org/pub/siege/siege-latest.tar.gz -o siege-latest.tar.gz
$ tar xvfz siege-latest.tar.gz
$ cd siege-*
$ ./configure
$ make
$ make install

It is important to note that if you want to load test an HTTPS (SSL) site, you'll need to install siege with SSL support. The Mac homebrew installation and Ubuntu package already enable this, by default.

$ ./configure --with-ssl

Enabling JSON support in siege

So, you're load testing a web application which uses JSON, huh? Does it look like your application is not recognizing the parameters as JSON? Yeah... as of siege 2.74 (currently the latest version), siege does not recognize .json files, nor does it support automatically setting the Content-Type: application/json request header. Bummer.

But you need JSON support, you say? Yeah, me too. Sadly, that means you get to edit some C source code. So, download the latest source (as instructed in the Installing siege section, above) and before you ./configure, you'll need to edit src/load.c:

static const struct ContentType tmap[] = {
  {"default", TRUE,  "application/x-www-form-urlencoded"},
  {"ai",      FALSE, "application/postscript"},
+ {"json",    FALSE, "application/json"},
  {"xyz",     FALSE, "chemical/x-pdb"},
  {"zip",     FALSE, "application/zip"}

Just add an entry to allow .json files to be recognized and transmitted as "application/json" format. Once that's done, re-configure, build, and install siege, as detailed above. Now, when the URLs file defines a .json file, siege will automatically recognize it and make the request with the proper Content-Type request header.


Once you've created or otherwise acquired your HAR file, use Hardy to convert it to a siege URLs file:

$ hardy convert my-har-file.env

By default, this will create a urls.siege file and a data directory full of data files to support it.

Hardy options

There are a handful of command line options when running the convert task, ranging from defining your output file to changing the data directory, and more. Check out hardy help convert for more details. Below are a few details of the more interesting ones:

--host-filter will restrict the generated URLs file to only include requests to the given host. This is very useful if your site uses a CDN for assets and you do not want to include those requests in your load test (that would be a bad idea!).

--host will replace the request hosts for all generated URLs with the host given. This is useful if you're generating your HAR script on one system (say, your staging server) and want to run the siege test against another (perhaps your production stack).

--protocol will replace the request protocols for all generated URLs with the protocol given. This is useful for creating one script where you're load testing https:// and another where you're load testing http://. Again, commonly useful when you're generating your HAR from a system different from the on you're running your siege against.

An example where we've generated a my-site.env HAR file by walking our staging site (http://staging.my-site.com) and we want to have siege run against our production site (https://www.my-site.com):

$ hardy my-site.env --host-filter=staging.my-site.com --host=www.my-site.com --protocol=https://

Using siege

Now, to use siege with your shiny new URLs file (and data directory), here's an example:

$ siege -c5 -d10 -t5M -v -f urls.siege

This tells siege to run with 5 concurrent users (-c5), ramping them up over 10 seconds (-d10), running with all 5 users active for 5 minutes (-t5M), displaying the request results to the screen (-v), and sourcing your URLs file for their run script (-f urls.siege).

siege offers a lot of settings options, so check out siege --help for more information.


  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request