status/usage of FRiCKLE/ngx_cache_purge. still reliable? alternatives?

[Robert Paprocki]

Hi,

On Wed, Jun 6, 2018 at 3:42 PM, PGNet Dev <pgnet.dev at gmail.com> wrote:

> Hi
>
> My $0.02 coming from experience building out scalable WP clusters is,
>> stick to Varnish here.
>>
>
> Miscommunication on my part -- my aforementioned Varnish-in-front referred
> to site dev in general.
>
> To date, it's been in front of Symfony sites.  Works like a champ there.
>
> Since you're apparently working with WP under real-world loads, do you
> perchance have a production-ready, V6-compatible VCL & nginx config you can
> share? or point to?
>


Nothing off the top of my head/isn't NDA-protected ;) But basic configs
will generally serve you well. Varnish and Nginx are mature, stable
projects; basic proxy_pass design with Nginx + basic Varnish config and a
PURGE method handler should suffice for most operations. Beyond that, tune
Nginx for buffer sizes and do a bit of kernel tweaking if necessary for
windowing, if you need.



> FRiCKLE's module is great, but it would be scary to put into production-
>> have fun with that test/release cycle :p
>
> Yep.  Hence my question(s)!
>


Right- my point is, it's not officially supported, and Nginx has no stable
API/ABI. With every release you want to leverage you need to walk through
your entire test/canary/B-G/whatever cycle. That's a question only you can
answer, but asking about "what about X release" is fruitless because of a
complete lack of ABI support. In six month's it's an obsolete question,
whose only two answers are "be the developer and watching the changelog" or
"compile the module, test it, and pray to the diety of your choice that it
doesn't explode".


>
> The overhead of putting Nginx in front of Varnish is fairly small in the
>> grand scheme of things. What's your motivation to strictly use Nginx?
>>
>
> This time 'round, it's not entirely 'my' motivation; came with the job's
> "prefer to haves".
>
> Based, in apparently large part, on the usual use of TheGoogle; these 2 in
> particular:
>
>
> https://deliciousbrains.com/page-caching-varnish-vs-nginx-fa
> stcgi-cache-2018/
>   https://www.scalescale.com/tips/nginx/nginx-vs-varnish/



Stepping back, these articles compare Nginx vs. Varnish straight-up. There
is considerable difference to take into account in examining a stack
leverage both.

And of course, always always always take into strong account the context
and limitations in which these articles were written. They do not care
about your particular business limitations, context, financial/resource
restrictions, or anything else that makes your situation useful. A large
grain of salt is always important to hold here.

In particular, the first article doesn't leverage keepalive (I maintain
"ab" is a horrid tool in this day and age), uses a cloud service with the
client living in who-knows-what-geographic/network-topology, and quite
frankly was written by an author who does not focus on systems/operations.
Tread wisely.

The second article is two and a half years old, offers no data whatsoever,
and touches on a number of irrelevant topics (SSL, h2). I'd steer clear of
any opinion offered here.

If I were you I would strongly question this "prefer to have" if the only
question is manageable cache purging. :)



> There is official support for cache purging with the commercial version of
>> Nginx: https://www.nginx.com/products/nginx/caching/.
>>
>
> Ah, so not (yet) in the FOSS product.  I see it's proxy_cache, not
> fastcgi_cache, based ...
>


I imagine that's a question for the sales folks, outside of this list :D
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