Varnish 5.0 changes to defaults

[Kristian Grønfeldt Sørensen]

On 7 December 2015 at 15:05, Geoff Simmons <geoff at uplex.de> wrote:

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> On 12/07/2015 02:30 PM, Rubén Romero wrote:
> >
> > While on the topic of changing defaults, I think we should include
> > Surrogate-Control and ESI parsing in to the builtin VCL as
> > discussed yesterday.
> >
> > This was discussed last year:
> > https://www.varnish-cache.org/trac/wiki/VDD14Q3#Surrogate-Control
> >
> > So we now need to follow-up on that and the discussions during VUGX
> > last week.
>
> The conversations we've had in the past were more about using
> Surrogate-Control to set TTLs that are targeted to the proxy, but not
> for downstream caches. I believe we never got further than "yes we
> should have that, and a VMOD should do it" -- partially my fault, I
> should add in fairness.
>
> I didn't want to get nitpicky about this at VUG, but there's a bit of
> a problem with Varnish adding Surrogate-Control:ESI/1.0 to the backend
> request header (whether by default or not), since Varnish does not in
> fact support the full 1.0 ESI spec -- only the include and remove
> tags. If the idea is that backends are informed that they can use ESI
> in their responses, either for Varnish or, say, a CDN that might use
> another proxy, "ESI/1.0" would suggest that the backends can use ESI
> tags that Varnish would ignore.
>
> I forgot that Varnish does not support the full ESI spec. I don't think
Varnish should signal ESI/1.0 as long as it doesn't support the full spec.
That could give some people an unpleasant surprise.


> If we really want to do this, the tag might have to be something like
> "ESI/Varnish" or "ESI/include&remove" or "VESI/x.y". (There's a
> precedent for the latter -- Oracle Web Cache uses "ORAESI/x.y.z".)
>

I would prefer if Varnish somehow advertised it's ESI capabilities by
default. I don't really have an opinion on how exactly it should be done as
long as we don't risk to break anything that correctly implements the full
ESI spec . Any of your 3 suggestions would work for me personally.

/Kristian
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