Seeing the Invisible: Two Years at Wikipedia with W3C's Network Error Logging

Wednesday, March 22, 2023 - 2:45 pm3:30 pm

Chris Danis, Wikimedia Foundation


If a user's packets get dropped in someone else's network, do they make a sound?

What if you could find out that your users can't reach your website—in near-real-time and completely automatically, with very low rates of both false negatives and false positives? This sounds too good to be true, but it has been exactly Wikipedia's experience as the most popular website in the world to implement W3C's Network Error Logging spec.

We'll give an overview of the technology itself, the tradeoffs Wikimedia made in our implementation, and case studies of several user-visible outages that NEL detected but traditional monitoring missed.

Chris Danis, Wikimedia Foundation

Chris is a lifelong tinkerer and a recovering ex-Googler. Currently an SRE at the Wikimedia Foundation, the non-profit that operates Wikipedia and other related projects, their work responsibilities mostly consist of wild hand-waving about incident response, symptom-focused alerting, and the follies of distributed systems.

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@conference {286236,
author = {Chris Danis},
title = {Seeing the Invisible: Two Years at Wikipedia with {W3C{\textquoteright}s} Network Error Logging},
year = {2023},
address = {Santa Clara, CA},
publisher = {USENIX Association},
month = mar,

Presentation Video