[PATCH] add documentation about backend naming for VMOD authors

[Dridi Boukelmoune]

>> In the "Writing a director" documentation I *recommend* directors
>> writers to back their director with a *VMOD object* because VMOD
>> object come with a *unique* vcl_name and don't outlive the VCL's
>> lifespan. It makes VMOD objects in my opinion the best facility to
>> write a director.
>
> Certainly, that's a good solution -- as long as your use case allows
> for it. You could even have an object generate multiple backends,
> using the object's name for a "safe namespace", within which it
> creates unique names (say by adding the ".%d" suffix).
>
> And you've made it clear that you're fully aware that using objects is
> not the only, necessary solution -- and even then, the VMOD has to go
> through the motions of using the object's vcl_name for backend names.

I apparently I haven't made it clear that I fully understand how VMOD
objects and backends are totally unrelated, except for the vcl_name on
which they can't collide.

> However the VMOD goes about it, uniqueness of naming with all of the
> consequences is something it has to take care of (or not, and take the
> consequences).
>
> Adding something to the Varnish/VRT interface to make it work right
> will go a long way to making this painless.
>
> D'accord?

I don't think it's a good idea to leave the end-user with unnamed
backends in the VSL that don't even appear in the CLI and VSM, or
confusing names in the CLI/VSM because of name collisions auto-repair.

I care way way more about the end-user's convenience rather than the
VMOD writer's. Especially since the rules to follow to ensure
uniqueness wouldn't even be hard, there isn't that much pain in my
opinion.

Best,
Dridi