[erlang-questions] configure http methods in yaws

[Bogdan Andu]

Hi,

I have the following config:

....
<server localhost>
        port = 8088
        listen = 127.0.0.1
        listen_backlog = 100
        dispatchmod = dispatch_rewrite
        docroot = /tmp
        revproxy = / http://127.0.0.1:8080/ intercept_mod intercept_cgi
</server>
.....


The precedence is dispatch_rewrite -> intercept_cgi ?

How it is possible to capture POST data in reverse proxy mode in
Yaws with dispatchmod dispatch_rewrite?

I try to capture POST data but Arg#arg.querydata is undefined.

I want to capture the POST string like a=1&b=2 to have it analyzed
in dispatchmod.

Also yaws_api:parse_post(Arg). doesn't work (perhaps uses
Arg#arg.querydata).

Thanks,
Bogdan



On Sun, Jun 28, 2015 at 6:20 PM, Bogdan Andu <bog495@REDACTED> wrote:

> Hi,
>
> I know the docs
> and I run internally Yaws in reverse proxy mode
> and I want this in Internet facing setup also
>
> I searched the net 'yaws reverse proxy' and I found:
>
> 1)
> http://stackoverflow.com/questions/917546/has-anybody-used-yaws-server-as-an-http-proxy
>    although 6 years  old, is Yaws in reverse proxy mode comparable or even
>    better than varnis, haproxy, nginx?
>
> 2) http://osdir.com/ml/web.server.yaws.general/2007-12/msg00000.html
>     this one is from klacke and he speaks about difficulties he
>     encountered writing revproxy engine.as well as an OTP limitation
>     being the main obstacle in overcoming these.
>     Are these still apply today?
>
> 3) also found this:
> http://www.erlang-factory.com/upload/presentations/752/reed-efsf2013-whatsapp.pdf
>     it seems whatsapp useses or used yaws in revproxy mode with some tweaks
>
> The setup I want is simple:
>
> Because I have the applications written in other language
> and for rewriting them in Erlang I dont have the time I must
> use this setup:
>
>  - Yaws in front-end in revproxy mode with interception module with plenty
> of check
> on headers, cookies, etc
>  - Twiggy/Starlet/Starman as back-end or psgi server
>    more info here: http://www.slideshare.net/kazeburo/yapc2013psgi-plack
>
>  I want to keepalive connections between yaws and psgi servers to avoid
>  3-way handshake overhead. Although with outside world I want disable
> keepalive
>   and set 'connection: close' and all of thiese can be done by altering
> the headers
>  tru interception module.
>
>
> Is it safe to keepalive connections between Yaws and Twiggy for
> example which is an Libevent implementation web server?
> Or Starlet/Starman like web server which has a parallel pre-fork model?
>
> Thanks and sorry for long post,
>
> Bogdan
>
>
>
>
> On Sun, Jun 28, 2015 at 4:51 AM, Steve Vinoski <vinoski@REDACTED> wrote:
>
>>
>>
>> On Sat, Jun 27, 2015 at 4:58 AM, Bogdan Andu <bog495@REDACTED> wrote:
>>
>>> Hi,
>>>
>>> About yaws as reverse proxy..
>>>
>>> I want to use yaws as a reverse proxy in a
>>> http -> http setup. no ssl involved whatsoever.
>>>
>>> I am interested in interception module where I want
>>> to apply various checks on headers, query string, etc
>>> making this some kind of www firewall .
>>>
>>> Is this feature of yaws production ready ?
>>>
>>
>> Yes. You can find details about it in chapter 13 of
>> http://yaws.hyber.org/yaws.pdf, or under the revproxy section of
>> http://yaws.hyber.org/yman.yaws?page=yaws.conf .
>>
>> --steve
>>
>>
>>
>>>
>>>
>>> Thanks,
>>> Bogdan
>>>
>>>
>>> On Fri, Feb 13, 2015 at 6:14 PM, Steve Vinoski <vinoski@REDACTED> wrote:
>>>
>>>> I don't recall seeing Yaws users asking for this config feature in the
>>>> past, so it's unlikely we'll add it. But what you're asking for -- a
>>>> configuration point for methods -- would be implemented much as I've shown
>>>> in my previous emails, much like a dispatchmod. The dispatchmod is as early
>>>> in the request handling process as you can get after the formation of the
>>>> #arg{}. The dispatchmod code I provided requires less configuration than
>>>> what you're showing, even for the default case, plus if having to have a
>>>> new module concerns you, the dispatch/1 function can be added to some other
>>>> existing module you already have instead.
>>>>
>>>> --steve
>>>>
>>>>
>>>>
>>>> On Fri, Feb 13, 2015 at 4:30 AM, Bogdan Andu <bog495@REDACTED> wrote:
>>>>
>>>>> Yes but the point is to have a default configuration that can be
>>>>> overridden by such a mechanism
>>>>> if one is configured.
>>>>> The 99 percent of cases only need a default behaviour.
>>>>>
>>>>> The way I see this is to have something like that (all in one):
>>>>>
>>>>> <LIMIT POST GET>
>>>>>         mod_405=my_405_handle_module
>>>>> ....
>>>>> </LIMIT>
>>>>>
>>>>> in this way we can also customize the response if a method other than
>>>>> GET or POST is sent to the server
>>>>>
>>>>> On Fri, Feb 13, 2015 at 10:17 AM, Imants Cekusins <imantc@REDACTED>
>>>>> wrote:
>>>>>
>>>>>> > Traffic with methods not allowed should be discarded with 405
>>>>>>
>>>>>> you see, someone else might prefer another action depending on method
>>>>>> not allowed.
>>>>>>
>>>>>> a dedicated attribute may be convenient but then someone would ask:
>>>>>> "how do I change the response code? how do I redirect?". Current
>>>>>> approach gives you choice.
>>>>>>
>>>>>> one of those cases when there is more than one approach, a prefers  A,
>>>>>> b prefers B. Both have a valid point.
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>
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