primary and fallback to backup -- try_files, proxy_pass, upstream?

[Denis Arh]

I will not even try to explain why I've tried the "hard" way first :)

Your solution It worked perfectly.

I've added "error_log /dev/null crit;" to "location /api {" so it does not
fill the log files with connection refused"


Thank you.


On Sun, Feb 14, 2010 at 1:55 PM, Maxim Dounin <mdounin at mdounin.ru> wrote:

> Hello!
>
> On Sun, Feb 14, 2010 at 01:43:55PM +0100, Denis Arh wrote:
>
> > What I would like to have is nginx first to try primary service and then
> to
> > fallback to the backup if primary is not available.
> >
> > What I've tried:
> >
> > 1. try_files:
> >
> >
> >     location /api {
> >         try_files @primary @backup;
>
> This won't work as try_files tris *files* (surprise!) and uses
> fallback uri if no one was found.  See syntax details here:
>
> http://wiki.nginx.org/NginxHttpCoreModule#try_files
>
> [...]
>
> > 2. upstream
> >
> > upstream backend {
> >     server localhost:81;
> >     server unix:/tmp/php-fpm.sock;
> > }
> >
> > location /api {
> >    proxy_pass http://backend;
> > }
> >
> > The first part of this solution works -- requests are first passed to
> > localhost:81 and handled there without any problems and if this one is
> down
> > requests go to the second server in the upstream.
>
> Not really.  Requests are randomly balanced between two servers
> you specified.  Once one of them down it uses another one to
> process requests.
>
> > What happens there is another 502 error:
> > error-log: *1840 recv() failed (104: Connection reset by peer) while
> reading
> > response header from upstream, client: ......, server: ......, request:
> "GET
> > /api HTTP/1.1", upstream: "http://unix:/tmp/php-fpm.sock:/api"
> >
> > How to configure fastcgi backend propery to handle this properly?
>
> You use proxy_pass, and all backends should be http.  Using
> fastcgi backend in one pool with http ones isn't an option.
>
> > Is there any way to make this work?
> > If both are possible, which one is better?
>
>     location /api {
>        error_page 502 504 = @fallback;
>        proxy_pass http://primary-backend;
>    }
>
>    location @fallback {
>        fastcgi_pass ...
>    }
>
> Maxim Dounin
>
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>



-- 
Denis Arh
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