<div dir="ltr">Hi,<div><br></div><div>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.</div><div><br></div><div>This link may prove useful: <a href="https://info.varnish-software.com/blog/backends-load-balancing">https://info.varnish-software.com/blog/backends-load-balancing</a></div><div><br></div><div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div>-- <br></div>Guillaume Quintard<br></div></div></div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Feb 18, 2021 at 4:51 AM Hamidreza Hosseini <<a href="mailto:hrhosseini@hotmail.com">hrhosseini@hotmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">




<div dir="ltr">
<div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
Hi,<br>
I want to adjust health check on my varnish backends, But I dont know how can I know they are healthy or not
<br>
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)).
<br>
</div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
How can I check this?<br>
</div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
```</div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
backend server1 {
<div>    .host = "<a href="http://server1.example.com" target="_blank">server1.example.com</a>";</div>
<div>    .probe = {</div>
<div>        .request =</div>
<div>          "HEAD / HTTP/1.1"</div>
<div>          "Connection: close"</div>
<div>          "User-Agent: Varnish Health Probe";</div>
<div>        .timeout = 1s;</div>
<div>        .interval = 5s;</div>
<div>        .window = 5;</div>
<div>        .threshold = 3;</div>
<div>    }</div>
}</div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
```<br>
</div>
</div>

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</blockquote></div>