What the Fastly outage can teach us about writing error messages

Re:What the Fastly outage can teach us about writing error m... by gonzo41 on Tuesday June 08, 2021 @10:55PM (#27443713)

So that looks like a stock Varnish 503. I'm pretty sure the magic behind fastly is a ton of Varnish cache. What's interesting (VCL can be unforgiving), also that it was a big central stuff up. Which makes me think they have layers and layers of caching in depth and some top level config just blacked out everything. I kind of would have thought they'd have lots of small instances.

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Re:What the Fastly outage can teach us about writing error m... by res0nat0r on Tuesday June 08, 2021 @11:03PM (#27443776)

Fastly is indeed powered by a lot of Varnish magic. My company used(s) them for the CDN for some of our large website frontends, and they have engineers which will help generate the insanely convoluted and large VCL templates which can be setup in your account and will handle all of the magic routing / caching / much more complex things you need for your origin.

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Re:What the Fastly outage can teach us about writing error m... by gonzo41 on Tuesday June 08, 2021 @11:12PM (#27443827)

Yeah I've used varnish before. I like it a lot, but I do think coloring inside the lines as much as possible is probably the safest thing. Some of the VMOD's and more exciting things you can do with varnish become really trick to manage.

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Re:What the Fastly outage can teach us about writing error m... by cbsks on Tuesday June 08, 2021 @11:45PM (#27444000)

> So that looks like a stock Varnish 503

Looks like it, except that Varnish has it spelled “Guru Meditation”, not “Guru Mediation”. Anyone know why that would be?

https://github.com/varnishcache/varnish-cache/search?q=medit...

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Re:What the Fastly outage can teach us about writing error m... by donavanm on Wednesday June 09, 2021 @12:07AM (#27444125)

You've found a kind "trap street". This disambiguates the error message generated from Fastly vs the error message generated from an origin which happens to use varnish as well.

Edit: As to why Fastly wants to expose the relatively stock error message instead of custom text, I dont know. My guess would be Faslty (or their customers) have tooling built around parsing the http response and they're preserving compatibility.

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Re:What the Fastly outage can teach us about writing error m... by dormando on Wednesday June 09, 2021 @01:35AM (#27444560)

https://twitter.com/dormando/status/1402466173778677764

my fault. I would sometimes monitor for "guru mediations" popping up to tell if we were throwing errors without it being caught by other systems. Among other reasons.

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Re:What the Fastly outage can teach us about writing error m... by miyuru on Wednesday June 09, 2021 @01:32AM (#27444546)

this question was already answered in the fastly outage thread.

It was to identify fastly's Varnish vs customer's Varnish.

https://news.ycombinator.com/item?id=27433139

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Re:What the Fastly outage can teach us about writing error m... by herpderperator on Tuesday June 08, 2021 @11:57PM (#27444062)

Try searching an older branch manually. GitHub only searches the main branch.

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Re:What the Fastly outage can teach us about writing error m... by transitorykris on Tuesday June 08, 2021 @11:43PM (#27443993)

This is not true

Edit: trying to reverse engineer the “magic”, architecture, and the failure from a varnish error message is folly, and misleads others. How do I know the comment is patently false? I ran those teams at Fastly for 3 years.

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Re:What the Fastly outage can teach us about writing error m... by ntauthority on Wednesday June 09, 2021 @01:36AM (#27444567)

Alternately, document your 'magic architecture' in public so that people don't have to offend you or other employees of the firm by making incorrect assumptions based on the little you do show in public.

Also helps others pick up if you do go out of business or end up acquired, and before you do it even leads to a more level playing field.

However I guess a level playing field wouldn't have given you a NYSE listing... so I guess you're just being selfish?

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Re:What the Fastly outage can teach us about writing error m... by gowld on Wednesday June 09, 2021 @12:42AM (#27444285)

Most outages are config errors. Code errors would be detected before they broke everything.

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