Re: Maintenance mode

From: Aleksandar Lazic <al-haproxy#none.at>
Date: Mon, 16 Jun 2008 23:53:46 +0200

On Mon 16.06.2008 23:47, Alexander Staubo wrote:
>On Mon, Jun 16, 2008 at 11:22 PM, Aleksandar Lazic <al-haproxy#none.at>
>wrote:
>> Maybe this can help you ;-)
>>
>> http://haproxy.1wt.eu/download/1.3/doc/architecture.txt
>>
>> 4. Soft-stop for application maintenance
>> 4.1 Soft-stop using a file on the servers
>
>Thanks -- that's an interesting approach, although it only gets me
>halfway there.
>
>If all backends are down, HAProxy will attempt to connect for a while
>and then give up and response with a 503. But there's no way, as far as
>I can tell, to have HAProxy distinguish between a "bad" 503 and a
>"good" 503; in the latter case I want to display a descriptive page
>rather than an error.
>
>Of course, we could modify the application to check for maintenance
>mode and return the appropriate page, but I would have to find a
>low-overhead way of doing that. I can't have every single request
>checking a file.

I think for this you will like backup option:

http://haproxy.1wt.eu/download/1.3/doc/haproxy-en.txt

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3.1) Server monitoring

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Since version 1.1.17, it is possible to specify backup servers. These servers are only sollicited when no other server is available. This may only be useful to serve a maintenance page, or define one active and one backup server (seldom used in TCP mode). To make a server a backup one, simply add the 'backup' option on its line. These servers also support cookies, so if a cookie is specified for a backup server, clients assigned to this server will stick to it even when the other ones come back. Conversely, if no cookie is assigned to such a server, the clients will get their cookies removed (empty cookie = removal), and will be balanced against other servers once they come back. Please note that there is no load-balancing among backup servers by default. If there are several backup servers, the second one will only be used when the first one dies, and so on. To force load-balancing between backup servers, specify the 'allbackups' option.

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and maybe

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4.6) Customizing errors
4.6.1) Relocation
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errorloc 503 http://192.168.114.58/error50x.html .
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just as an idea.

Hth

Aleks Received on 2008/06/16 23:53