Mailing List Archive: health check varnish

health check varnish

Dec 30, 2021, 12:16 AM

Post #1 of 3 (520 views)

Hello all, first off all, thanks for a year full of varnish happiness
like the developers page and the parallel ESI for the varnish-cache edition.

We use the following in the vcl for our varnish health check from our
haproxy loadbalancers

if (req.url == "/varnish_status") {
        if (!std.healthy(req.backend_hint)) {
            return (synth(500, "Varnish: unhealthy backend."));
        }
        else {
            return (synth(200, "Varnish: All good!"));
        }
    }

And this works fine if we run varnish on the webserver itself with only
one backend.
But if we use the director with multiple backends we get an 500 error if
one of the backend servers is offline even if the director itself has
enough servers left and still is marked ad healthy.

Is there a way to check if the director itself is down?

like
Backend name      Admin    Probe    Health     Last change
boot.web01        probe    5/5      healthy    Mon, 27 Dec 2021 08:42:58 GMT
boot.web02        probe    5/5      healthy    Mon, 27 Dec 2021 08:42:58 GMT
boot.web03        probe    5/5      healthy    Mon, 27 Dec 2021 08:42:58 GMT
boot.webcluster   probe    2/2      healthy    Mon, 27 Dec 2021 08:42:58 GMT

return a 200 as all is good

boot.web01        probe    2/5      sick       Wed, 29 Dec 2021 18:33:41 GMT
boot.web02        probe    4/5      healthy    Wed, 29 Dec 2021 18:33:41 GMT
boot.web03        probe    4/5      healthy    Wed, 29 Dec 2021 18:33:41 GMT
boot.webcluster   probe    1/2      healthy    Wed, 29 Dec 2021 18:33:41 GMT

still return a 200 as we still have a healthy webcluster backend.

Backend name      Admin    Probe    Health    Last change
boot.web01        probe    2/5      sick      Wed, 29 Dec 2021 18:34:40 GMT
boot.web02        probe    2/5      sick      Wed, 29 Dec 2021 18:34:40 GMT
boot.web02        probe    2/5      sick      Wed, 29 Dec 2021 18:34:40 GMT
boot.webcluster   probe    0/2      sick      Wed, 29 Dec 2021 18:34:40 GMT

return the 500 error code as our webcluster backend is down.

So can we just get the health status of webcluster in this case?

regards
Johan

And in advance a happy new year.

_______________________________________________
varnish-misc mailing list
varnish-misc@varnish-cache.org
https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc

Re: health check varnish [ In reply to ]

dridi at varni

Dec 30, 2021, 1:17 AM

Post #2 of 3 (520 views)

Permalink

On Thu, Dec 30, 2021 at 8:17 AM Johan Hendriks <joh.hendriks@gmail.com> wrote:
>
> Hello all, first off all, thanks for a year full of varnish happiness
> like the developers page and the parallel ESI for the varnish-cache edition.
>
> We use the following in the vcl for our varnish health check from our
> haproxy loadbalancers
>
> if (req.url == "/varnish_status") {
> if (!std.healthy(req.backend_hint)) {
> return (synth(500, "Varnish: unhealthy backend."));
> }
> else {
> return (synth(200, "Varnish: All good!"));
> }
> }
>
> And this works fine if we run varnish on the webserver itself with only
> one backend.
> But if we use the director with multiple backends we get an 500 error if
> one of the backend servers is offline even if the director itself has
> enough servers left and still is marked ad healthy.
>
> Is there a way to check if the director itself is down?
>
> like
> Backend name Admin Probe Health Last change
> boot.web01 probe 5/5 healthy Mon, 27 Dec 2021 08:42:58 GMT
> boot.web02 probe 5/5 healthy Mon, 27 Dec 2021 08:42:58 GMT
> boot.web03 probe 5/5 healthy Mon, 27 Dec 2021 08:42:58 GMT
> boot.webcluster probe 2/2 healthy Mon, 27 Dec 2021 08:42:58 GMT
>
> return a 200 as all is good
>
> boot.web01 probe 2/5 sick Wed, 29 Dec 2021 18:33:41 GMT
> boot.web02 probe 4/5 healthy Wed, 29 Dec 2021 18:33:41 GMT
> boot.web03 probe 4/5 healthy Wed, 29 Dec 2021 18:33:41 GMT
> boot.webcluster probe 1/2 healthy Wed, 29 Dec 2021 18:33:41 GMT
>
> still return a 200 as we still have a healthy webcluster backend.
>
> Backend name Admin Probe Health Last change
> boot.web01 probe 2/5 sick Wed, 29 Dec 2021 18:34:40 GMT
> boot.web02 probe 2/5 sick Wed, 29 Dec 2021 18:34:40 GMT
> boot.web02 probe 2/5 sick Wed, 29 Dec 2021 18:34:40 GMT
> boot.webcluster probe 0/2 sick Wed, 29 Dec 2021 18:34:40 GMT
>
> return the 500 error code as our webcluster backend is down.
>
> So can we just get the health status of webcluster in this case?

If you assign webcluster.backend() to req.backend_hint before
performing the health check it should work fine.

Dridi
_______________________________________________
varnish-misc mailing list
varnish-misc@varnish-cache.org
https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc

Re: health check varnish [ In reply to ]

joh.hendriks at gmail

Dec 31, 2021, 4:41 AM

Post #3 of 3 (519 views)

Permalink

On 30/12/2021 10:17, Dridi Boukelmoune wrote:
> On Thu, Dec 30, 2021 at 8:17 AM Johan Hendriks <joh.hendriks@gmail.com> wrote:
>> Hello all, first off all, thanks for a year full of varnish happiness
>> like the developers page and the parallel ESI for the varnish-cache edition.
>>
>> We use the following in the vcl for our varnish health check from our
>> haproxy loadbalancers
>>
>> if (req.url == "/varnish_status") {
>> if (!std.healthy(req.backend_hint)) {
>> return (synth(500, "Varnish: unhealthy backend."));
>> }
>> else {
>> return (synth(200, "Varnish: All good!"));
>> }
>> }
>>
>> And this works fine if we run varnish on the webserver itself with only
>> one backend.
>> But if we use the director with multiple backends we get an 500 error if
>> one of the backend servers is offline even if the director itself has
>> enough servers left and still is marked ad healthy.
>>
>> Is there a way to check if the director itself is down?
>>
>> like
>> Backend name Admin Probe Health Last change
>> boot.web01 probe 5/5 healthy Mon, 27 Dec 2021 08:42:58 GMT
>> boot.web02 probe 5/5 healthy Mon, 27 Dec 2021 08:42:58 GMT
>> boot.web03 probe 5/5 healthy Mon, 27 Dec 2021 08:42:58 GMT
>> boot.webcluster probe 2/2 healthy Mon, 27 Dec 2021 08:42:58 GMT
>>
>> return a 200 as all is good
>>
>> boot.web01 probe 2/5 sick Wed, 29 Dec 2021 18:33:41 GMT
>> boot.web02 probe 4/5 healthy Wed, 29 Dec 2021 18:33:41 GMT
>> boot.web03 probe 4/5 healthy Wed, 29 Dec 2021 18:33:41 GMT
>> boot.webcluster probe 1/2 healthy Wed, 29 Dec 2021 18:33:41 GMT
>>
>> still return a 200 as we still have a healthy webcluster backend.
>>
>> Backend name Admin Probe Health Last change
>> boot.web01 probe 2/5 sick Wed, 29 Dec 2021 18:34:40 GMT
>> boot.web02 probe 2/5 sick Wed, 29 Dec 2021 18:34:40 GMT
>> boot.web02 probe 2/5 sick Wed, 29 Dec 2021 18:34:40 GMT
>> boot.webcluster probe 0/2 sick Wed, 29 Dec 2021 18:34:40 GMT
>>
>> return the 500 error code as our webcluster backend is down.
>>
>> So can we just get the health status of webcluster in this case?
> If you assign webcluster.backend() to req.backend_hint before
> performing the health check it should work fine.
>
> Dridi

Thank you, that did the trick. I knew it had to be something simple that
i overlooked.
Have a wonderful 2022 all.

regards
Johan

_______________________________________________
varnish-misc mailing list
varnish-misc@varnish-cache.org
https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc