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From Faysal Banna <degre...@gmail.com>
Subject Re: Migrating from squid
Date Fri, 27 Feb 2015 09:16:53 GMT
Sir.
the best way to use or migrate that feature is to do ts_lua .. i been doing
it for a while now and it works perfectly

it has everything one needs and you can at any time use os.execute from
inside Lua script
or you can use

local handle = io.popen(command)local result = handle:read("*a")
handle:close()

if you need a result. and its asynchronous with the system so it won't
block other operations in ATS.

its fast and pretty good to use.


i use it lately to rate-limit incoming connections from origin servers
and save bandwidth for certain object downloads.

if you need any assistance i may be able to help

much regards


On Fri, Feb 27, 2015 at 7:51 AM, J David <j.david.lists@gmail.com> wrote:

> (Not sure if this is best for the user list or the dev list, as it's
> development, but not of ATS per se.)
>
> Squid offers a feature called url_rewrite_program that can be used to
> change its behavior based on client IP, requested URL, and various
> other criteria.  It runs a bunch of copies of an external program and
> passes information to and from them over pipes.
>
> Overall, ATS is a much better fit for our environment, but we are
> heavily dependent on this feature of Squid.
>
> The short version of what we need to do is this:
>
> Based on a (ClientIP,RequestURL) pair, either choose a backend (by
> name or IP) to handle the request *or* issue an arbitrary redirect
> *or* return an HTTP error.
>
> According to the "squid config translation" docs, the equivalent for
> url_rewrite_program is remap.config.  Since that does not actually
> support external programs, it appears the intent is to use the
> built-in remapping abilities to replicate the functionality of the
> external program.  However, that is not always possible.
>
> The messy part that prevents us from doing that or hacking up a module
> is that the external program we use with squid is ridiculously
> complicated, pulling together information from multiple sources, all
> of them dynamic, and gets linked to all kinds of libraries like MySQL,
> memcached, and distributed message passing stuff.
>
> What is the best way to migrate this functionality to ATS?  The whole
> big ball of wax seems like a really poor candidate for a built-in ATS
> module due to all the external dependencies, many of which run
> asynchronously and can block.  It seems really advantageous to seal
> that off So what we probably really need is a pretty efficient way to
> emulate squid's ability to call out to an external program.
>
> If that's true, has anyone done something similar?  Which ATS module
> hook(s) would be the best to use, and how would we handle the need to
> yield while we wait for the external program to work?
>
> Thanks for any advice!
>



-- 
============================
         Faysal Banna
 Meteorological Services
Rafic Harriri International Airport
      Beirut - Lebanon
    Mob: +961-3-258043
=============================

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