Recording with Brotli Encoding - Web Performance

Recording with Brotli Encoding

Load Tester 6.7 and earlier does not support Brotli encoding. This is obviously planned for future releases, but for now you may need to use this workaround. If the site just has brotli on static pages there’s no need to do anything special, but if you are testing a site that is using Brotli encoding on security API calls that return session variables you’ll want to read on.

Brotli encoding has been gaining in popularity because it was designed from the group up for streaming. As a result, it reduces latency over gzip, which was originally designed for files in which compression ratio was the most important attribute. Load Tester will support it in the future, but right now you may have seen content that looks like this in your recordings:

If the content doesn’t contain any dynamic variables this wouldn’t matter from a load testing perspective, but if you’re trying to implement OAUTH or some other sort of dynamic variables you’ll want to turn off brotli in the browser. To turn off brotli you’ll want to install Chrome’s header modification plugin. You’ll need to configure the plugin to modify the “accept-encoding” HTTP header to accept only “gzip, deflate” as shown below.

When recording a test case with Load Tester and Chrome, by default the browser will come up in Incognito Mode, which bypasses the plugin. So, when you’re recording, you’ll need to ignore the Incognito window and open a regular window instead using “Control-N”.

As a reminder, Chrome can’t be already running when you start recording! Typically you’ll want to isolate your test environment anyway, running Load Tester in a clean virtual machine while your work computer/browser is somewhere else.

After re-recording the test case with this technique the page that did have encoded binary content only will now show up in Load Tester as text that can be parsed:

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