In that case I'm not sure how to make it work. Seems like you will need to
modify http_proto.c to cause the request to attempt to be redispatched when
haproxy receives a valid 502 http response from the server. I doubt that
this is the only thing to change, but it probably involves changing this
section of code and others:
if (unlikely(msg->msg_state < HTTP_MSG_BODY)) {
/* Invalid response */
if (unlikely(msg->msg_state == HTTP_MSG_ERROR)) {
/* we detected a parsing error. We want to archive
this response
* in the dedicated proxy area for later
troubleshooting.
*/
hdr_response_bad:
if (msg->msg_state == HTTP_MSG_ERROR || msg->err_pos
>= 0)
http_capture_bad_message(&s->be->invalid_rep, s, rep, msg, s->fe);
s->be->counters.failed_resp++;
if (s->srv) {
s->srv->counters.failed_resp++;
health_adjust(s->srv,
HANA_STATUS_HTTP_HDRRSP);
}
abort_response:
buffer_auto_close(rep);
rep->analysers = 0;
txn->status = 502;
rep->prod->flags |= SI_FL_NOLINGER;
buffer_ignore(rep, rep->l - rep->send_max);
stream_int_retnclose(rep->cons, error_message(s,
HTTP_ERR_502));
if (!(s->flags & SN_ERR_MASK))
s->flags |= SN_ERR_PRXCOND;
if (!(s->flags & SN_FINST_MASK))
s->flags |= SN_FINST_H;
return 0;
}
The server level redispatch function appears to really be designed for
backend server connect failures so this is most likely a bad idea.
-Jerry
Jerry Champlin
Absolute Performance Inc.
--
Enabling businesses to deliver critical applications at lower cost and
higher value to their customers.
On Mon, Aug 23, 2010 at 5:15 PM, Dustin Moskovitz <mos...@asana.com> wrote:
> If I understand correctly, that sends a redirect request back to the
> client? We need this for RPCs, so that won't really work.
>
>
> On Mon, Aug 23, 2010 at 3:50 PM, Jerry Champlin <
> j...@absolute-performance.com> wrote:
>
>> Dustin:
>>
>> It's a little more elaborate and potentially dangerous than I was
>> thinking, but this link illustrates a way to do what I think you are after.
>> http://www.formilux.org/archives/haproxy/0906/2144.html
>>
>> The solution from Maciej Bogucki is pasted below for ease:
>>
>> frontend fr1
>>
>> default_backend back_1
>> rspirep ^HTTP/...\ [23]0..* \0\nSet-Cookie:\
>> cookiexxx=0;path=/;domain=.yourdomain.com
>> rspirep ^(HTTP/...)\ 5[0-9][0-9].* \1\ 202\ Again\
>>
>> Please\nSet-Cookie:\
>> cookiexxx=1;path=/;domain=.yourdomain.com\nRefresh:\ 6\nContent-Length:\
>> Lenght_xxx\nContent-Type:\ text/html\n\n<FRAMESET\ cols="100%"><FRAME\ src="
>> http://www.yourdomain.com/redispatch.pl";>
>>
>> backend back_1
>>
>> cookie cookiexxx
>> server chk1 127.0.0.1:81 weight 1 check
>> server chk2 127.0.0.1:82 weight 1 check
>> server chk3 127.0.0.1:83 weight 1 check cookie 1 backup
>>
>> -Jerry
>>
>> Jerry Champlin
>> Absolute Performance Inc.
>> --
>> Enabling businesses to deliver critical applications at lower cost and
>> higher value to their customers.
>>
>>
>> On Mon, Aug 23, 2010 at 2:13 PM, Dustin Moskovitz <mos...@asana.com>wrote:
>>
>>> Hey Jerry, can you elaborate?
>>>
>>> To be clear what happens is:
>>> 1/ proxy receives requests
>>> 2/ proxy sends request to webserver
>>> 3/ webserver sends 502 response to proxy
>>> 4/ proxy forwards 502 response to the end user
>>>
>>> I do have other webservers that I want to re-dispatch the request to - is
>>> that what you mean by backup servers? In any case, it seems like the proxy
>>> must be the one responsible for handling the failure.
>>>
>>>
>>> On Fri, Aug 20, 2010 at 12:08 PM, Jerry Champlin <
>>> j...@absolute-performance.com> wrote:
>>>
>>>> It seems like you could configure backup servers within the pool to
>>>> accomplish this although it's not quite as clean as what I suspect you are
>>>> looking for.
>>>>
>>>> -Jerry
>>>>
>>>> Jerry Champlin
>>>> Absolute Performance Inc.
>>>> --
>>>> Enabling businesses to deliver critical applications at lower cost and
>>>> higher value to their customers.
>>>>
>>>>
>>>>
>>>> On Fri, Aug 20, 2010 at 12:54 PM, Dustin Moskovitz <mos...@asana.com>wrote:
>>>>
>>>>> Hi all,
>>>>> We run haproxy in front of a bank of nginx servers, which each proxy
>>>>> requests to a custom web server on the same box.
>>>>>
>>>>> I was wondering if it is possible to configure haproxy such that it
>>>>> will redispatch requests that receive a 502 from nginx to a new server. I
>>>>> looked through the docs but could not find anything that seemed relevant.
>>>>>
>>>>> Dustin
>>>>>
>>>>
>>>>
>>>
>>
>
