cache warming strategies

Hettwer, Marian mhettwer at
Mon Apr 18 13:44:59 CEST 2011

Hi All,

I'm thinking about how to auto warm my varnish caches.
I have a list of cacheable urls which I like to refresh once in a while to
make sure that whenever somebody hits that page, it's really a cache hit.

I'm wondering about best practices with regards to holding a cache warm.

I remember that I saw an eMail on this list where somebody used a curl
based script with a specific http header. Whenever that http header was
set, the vcl logic said "go and fetch from backend". However, I can't find
that mail anymore and I cant remember how it was accomplished.

I also remember something about the reaper thread which is clearing the
cache and whenever it's about to remove an object from cache, there was a
way to tell varnish to not delete the object, but rather re-fetch it.
Again, I can't find any documentation about. Is my mind playing tricks on
me?! :)

Long Story Short: Any advices on how to keep the cache warm?

Thanks in advance,
Marian Hettwer | Site Ops Engineer | GmbH
Fon:     + 49-(0)30-8109 - 7332
Fax:     + 49-(0)30-8109 - 7131

Mail:     mhettwer at

Marktplatz 1 | 14532 Europarc Dreilinden | Germany

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