stale-if-error in varnish 4.1?

[Angelo Höngens]

Hey guys and girls,

I got a question from one of my webdevs if and how varnish can do stale-if-error.

I can't find much about the subject. I found a document[1] stating: "Varnish 4.1 implements stale-while-revalidate for the first time, but not stale-if-error."

I found an article on fastly.com [2] dating from 2014 that says: "Fastly is excited to announce that as of today, we support stale-while-revalidate and stale-if-error.", so that would seem to contradict the previous statement. Fastly uses normal varnish right?

Googling some more I found another page on docs.fastly.com [3] that explains how to do stale-if-error: do some custom VCL hacking. They do stuff with 'stale.exists' and restarts. I've been working with varnish for a while, but it looks like my varnish 4.1 instance doesn't know the 'stale.exists' thingy and I have no idea how restarts work.

2 questions for you smart guys and girls:

- I native stale-if-error on the roadmap?
- How can I hack stale-if-error in my VCL using my varnish41 machines?



References: 

[1] https://varnishfoo.info/varnishfoo.pdf
[2] https://www.fastly.com/blog/stale-while-revalidate-stale-if-error-available-today
[3] https://docs.fastly.com/guides/performance-tuning/serving-stale-content

-- 
 
With kind regards,
 
 
Angelo Höngens
 
Systems Administrator
 
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NetMatch
travel technology solutions

Professor Donderstraat 46
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T: +31 (0)13 5811088
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mailto:A.Hongens at netmatch.nl
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