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Comment by gonzo41 | Hacker News Reader

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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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.

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.

> 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...

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.

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.

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

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

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.

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?

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

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