Upstream service php-fpm is up and running but reports {"errors": {"status_code": 502,"status": "php-fpm server is down"}}

[Kaushal Shriyan]

On Fri, Dec 16, 2022 at 1:38 AM Maxim Dounin <mdounin at mdounin.ru> wrote:

> Hello!
>
> On Thu, Dec 15, 2022 at 09:53:11PM +0530, Kaushal Shriyan wrote:
>
> >
> > I am running the nginx version: nginx/1.22 as a reverse proxy server on
> > CentOS Linux release 7.9.2009 (Core). When I hit
> http://mydomain.com/apis I
> > see the below message on the browser even if the upstream server php-fpm
> > server is up and running.
> >
> > *{"errors": {"status_code": 502,"status": "php-fpm server is down"}}*
> >
> > I have set the below in the nginx.conf file and attached the file for
> your
> > reference.
> >
> > if ($upstream_http_content_type = "") {
> >                      add_header 'Content-Type' 'application/json' always;
> >                      add_header 'Content-Type-3'
> > $upstream_http_content_type$isdatatypejson"OK" always;
> >                       return 502 '{"errors": {"status_code":
> 502,"status":
> > "php-fpm server is down"}}';
> >                   }
>
> The "if" directive makes it possible to conditionally select
> configuration to handle a request, and therefore can only use
> information available before the request is handled.  In your
> case, before the request is sent to the upstream server.  See
> http://nginx.org/en/docs/http/ngx_http_rewrite_module.html for
> more details.
>
> As such, $upstream_http_content_type will be always empty, since
> there are no upstream response yet, and therefore the
> configuration will always return 502.  This matches your
> observations.
>
> An obvious fix would be to remove the configuration chunk in
> question.
>
> Instead, you probably need something like:
>
>     error_page 502 /502.json;
>
>     location = /502.json {
>         return 200 '{"errors": {"status_code": 502, "status": "php-fpm
> server is down"}}';
>     }
>
>
Thanks Maxim for the suggestion. I will try it out and keep you posted with
the testing as it progresses. I am obliged to this mailing list. Thanks in
advance.

Best Regards,

Kaushal
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