Varnish Health check

[Guillaume Quintard]

please keep the mailing-list in CC for future communications.

> Open error 111 (Connection refused)

This is a TCP issue, the backend is just not accepting the connection, are
you sure the IP:PORT is right?

-- 
Guillaume Quintard


On Thu, Feb 18, 2021 at 8:16 AM Hamidreza Hosseini <hrhosseini at hotmail.com>
wrote:

> I read you article and it was great but I didn't find out my answer, I
> said that I have 2 layer varnish:  disk layer and ram layer and ram layer,
> I want to check the health of layer 2 for example:
>
> Varnish Ram ===> Varnish Disk ===> Webserver
> I adjust this probe on varnish ram:
>
> probe myprobe {
>     .request =
>       "HEAD / HTTP/1.1"
>       "Connection: close"
>       "User-Agent: Varnish Health Probe";
>     .timeout = 1s;
>     .interval = 5s;
>     .window = 5;
>     .threshold = 3;
> }
> and varnish says: ` 0 Backend_health - boot.varnish_1 Still sick --------
> 0 3 5 0.000000 0.000000 Open error 111 (Connection refused)`
> And I think it is right because it checks HEAD / on varnish backends and
> there is nothing there!
> So I'm asking how should I configure the probe to trigger another varnish
> health as a backend
>
> Best regards.
>
> ------------------------------
> *From:* Guillaume Quintard <guillaume at varnish-software.com>
> *Sent:* Thursday, February 18, 2021 7:14 AM
> *To:* Hamidreza Hosseini <hrhosseini at hotmail.com>
> *Subject:* Re: Varnish Health check
>
> Ah, I missed the multilayer setup. In that case, you can have a look at
> this one: https://info.varnish-software.com/blog/howto-respond-to-probes
> --
> Guillaume Quintard
>
>
> On Thu, Feb 18, 2021 at 7:08 AM Hamidreza Hosseini <hrhosseini at hotmail.com>
> wrote:
>
> How can I probe a backend varnish? for example I have 2 layer varnish disk
> layer and ram layer and ram layer want to check the health of layer 2, How
> can I do this? I've done something but I have error:
>
> sudo varnishadm backend.list -p
> Backend name                   Admin      Probe                Last updated
> boot.varnish_1                 probe      Sick                0/5
>   Current states  good:  0 threshold:  3 window:  5
>   Average response time of good probes: 0.000000
>   Oldest ================================================== Newest
>   ---------------------------------------------------------------- Happy
>
> sudo varnishlog -g raw -i Backend_health
> 0 Backend_health - boot.varnish_1 Still sick -------- 0 3 5 0.000000
> 0.000000 Open error 111 (Connection refused)
>
> my config:
> probe myprobe {
>     .request =
>       "HEAD / HTTP/1.1"
>       "Connection: close"
>       "User-Agent: Varnish Health Probe";
>     .timeout = 1s;
>     .interval = 5s;
>     .window = 5;
>     .threshold = 3;
> }
> ------------------------------
> *From:* Guillaume Quintard <guillaume at varnish-software.com>
> *Sent:* Thursday, February 18, 2021 7:00 AM
> *To:* Hamidreza Hosseini <hrhosseini at hotmail.com>
> *Cc:* varnish-misc at varnish-cache.org <varnish-misc at varnish-cache.org>
> *Subject:* Re: Varnish Health check
>
> Hi,
>
> The answer will be highly dependent on your setup, usually you want to
> find a probe request that will truly test the backend. One option, if you
> have control over the backend is to write a page to test the subsystem and
> make sure everybody's up.
>
> This link may prove useful:
> https://info.varnish-software.com/blog/backends-load-balancing
>
> --
> Guillaume Quintard
>
>
> On Thu, Feb 18, 2021 at 4:51 AM Hamidreza Hosseini <hrhosseini at hotmail.com>
> wrote:
>
> Hi,
> I want to adjust health check on my varnish backends, But I dont know how
> can I know they are healthy or not
> because the nodes are up and running and even service is up but varnish
> does'nt work for all requests (just third of them are responding till I
> restart it (It happens sometimes)).
> How can I check this?
> ```
> backend server1 {
>     .host = "server1.example.com";
>     .probe = {
>         .request =
>           "HEAD / HTTP/1.1"
>           "Connection: close"
>           "User-Agent: Varnish Health Probe";
>         .timeout = 1s;
>         .interval = 5s;
>         .window = 5;
>         .threshold = 3;
>     }
> }
> ```
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