web backend is sick

[Stefan Caunter]

34 milliseconds? You are asking for your backend to get marked sick
all the time with this value on an apache server. You just want to
know if it has totally gone away. Set the timeout to 5 seconds. You
can do some beautiful tuning if you really understand your web app and
want to move varnish away from sick backends, but for now, you just
need to use both your backends, and let varnish protect them.


----

Stefan Caunter
ScaleEngine Inc.
E: stefan.caunter at scaleengine.com
Toronto Canada


On Mon, May 12, 2014 at 11:03 PM, Tim Dunphy <bluethundr at gmail.com> wrote:
> Hi Nick,
>
> Thanks for your reply! I tried a different probe. No luck so far:
>
> backend web1  {
>   .host = "10.10.1.94";
>   .port = "80";
>   .probe = {
>                 .url = "/healthcheck.html";
>                 .timeout = 34 ms;
>                 .interval = 1s;
>                 .window = 10;
>                 .threshold = 8;
>   }
> }
>
> backend web2  {
>
>   .host = "10.10.1.98";
>   .port = "80";
>     .probe = {
>                 .url = "/healthcheck.html";
>                 .timeout = 34 ms;
>                 .interval = 1s;
>                 .window = 10;
>                 .threshold = 8;
>   }
> }
>
> director www client {
>   { .backend = web1 ; .weight = 2;  }
>   { .backend = web2 ; .weight = 2;  }
>  }
>
>
> This is all the healthcheck file does:
>
> [root at beta:/var/www/jf-ref] #cat healthcheck.html
> good
>
> Drum roll please!! AAAAnnnnnd:
>
> [root at varnish1:/etc/varnish] #varnishlog | grep web2
>     0 Backend_health - web2 Still sick ------- 0 8 10 0.000000 0.000000
>     0 Backend_health - web2 Still sick ------- 0 8 10 0.000000 0.000000
>     0 Backend_health - web2 Still sick ------- 0 8 10 0.000000 0.000000
>     0 Backend_health - web2 Still sick ------- 0 8 10 0.000000 0.000000
>     0 Backend_health - web2 Still sick ------- 0 8 10 0.000000 0.000000
>     0 Backend_health - web2 Still sick ------- 0 8 10 0.000000 0.000000
>     0 Backend_health - web2 Still sick ------- 0 8 10 0.000000 0.000000
>     0 Backend_health - web2 Still sick ------- 0 8 10 0.000000 0.000000
>     0 Backend_health - web2 Still sick ------- 0 8 10 0.000000 0.000000
>
> Bummer. :(
>
> No joy at all.
>
> Thanks for playing!
> Tim
>
>
> On Mon, May 12, 2014 at 10:03 PM, nick tailor <nick.tailor at gmail.com> wrote:
>>
>> Try using a custom health check probe
>>
>> On May 9, 2014 10:00 PM, "Tim Dunphy" <bluethundr at gmail.com> wrote:
>>>
>>> Hey all,
>>>
>>>  I have two web backends in my varnish config. And one node is reporting
>>> healthy and the other is being reported as 'sick'.
>>>
>>> 10 Backend      c 11 www web1
>>>     0 Backend_health - web1 Still healthy 4--X-RH 5 3 5 0.001130 0.001067
>>> HTTP/1.1 200 OK
>>>     0 Backend_health - web1 Still healthy 4--X-RH 5 3 5 0.001231 0.001108
>>> HTTP/1.1 200 OK
>>>     0 Backend_health - web1 Still healthy 4--X-RH 5 3 5 0.001250 0.001143
>>> HTTP/1.1 200 OK
>>>     0 Backend_health - web1 Still healthy 4--X-RH 5 3 5 0.001127 0.001139
>>> HTTP/1.1 200 OK
>>>     0 Backend_health - web1 Still healthy 4--X-RH 5 3 5 0.001208 0.001157
>>> HTTP/1.1 200 OK
>>>     0 Backend_health - web1 Still healthy 4--X-RH 5 3 5 0.001562 0.001258
>>> HTTP/1.1 200 OK
>>>     0 Backend_health - web1 Still healthy 4--X-RH 5 3 5 0.001545 0.001330
>>> HTTP/1.1 200 OK
>>>     0 Backend_health - web1 Still healthy 4--X-RH 5 3 5 0.001363 0.001338
>>> HTTP/1.1 200 OK
>>>    11 BackendClose b web1
>>>
>>> [root at varnish1:/etc/varnish] #varnishlog | grep web2
>>>     0 Backend_health - web2 Still sick 4--X--- 0 3 5 0.000000 0.000000
>>>     0 Backend_health - web2 Still sick 4--X--- 0 3 5 0.000000 0.000000
>>>     0 Backend_health - web2 Still sick 4--X--- 0 3 5 0.000000 0.000000
>>>     0 Backend_health - web2 Still sick 4--X--- 0 3 5 0.000000 0.000000
>>>     0 Backend_health - web2 Still sick 4--X--- 0 3 5 0.000000 0.000000
>>>     0 Backend_health - web2 Still sick 4--X--- 0 3 5 0.000000 0.000000
>>>     0 Backend_health - web2 Still sick 4--X--- 0 3 5 0.000000 0.000000
>>>     0 Backend_health - web2 Still sick 4--X--- 0 3 5 0.000000 0.000000
>>>     0 Backend_health - web2 Still sick 4--X--- 0 3 5 0.000000 0.000000
>>>
>>> And I'm really at a loss to understand why. Both nodes should be
>>> completely identical. And the web roots on both are basically svn repos that
>>> are in sync.
>>>
>>> From web1 :
>>>
>>> [root at beta:/var/www/jf-current] #svn info | grep -i revision
>>> Revision: 17
>>>
>>> To web2:
>>>
>>> [root at beta-new:/var/www/jf-current] #svn info | grep -i revision
>>> Revision: 17
>>>
>>> This is the part of my vcl file where I define the web back ends:
>>>
>>> probe favicon {
>>>   .url = "/favicon.ico";
>>>   .timeout = 60ms;
>>>   .interval = 2s;
>>>   .window = 5;
>>>   .threshold = 3;
>>> }
>>>
>>> backend web1  {
>>>   .host = "xx.xx.xx.xx";
>>>   .port = "80";
>>>   .probe = favicon;
>>> }
>>>
>>> backend web2  {
>>>
>>>   .host = "xx.xx.xx.xx";
>>>   .port = "80";
>>>   .probe = favicon;
>>> }
>>>
>>> And the file that varnish is probing for is present on both:
>>>
>>> [root at beta:/var/www/jf-current] #ls -l /var/www/jf-current/favicon.ico
>>> -rwxrwxr-x 1 apache ftp 1150 Dec 22 00:53 /var/www/jf-current/favicon.ico
>>>
>>> I've also setup individual web URLs for each host that isn't cached in
>>> varnish so I can hit each one. And each site comes up ok. So I'm a little
>>> puzzled as to why the second web host is reporting 'sick' and what I can do
>>> to get it back into load balancing.
>>>
>>> Thanks for any help you can provide!
>>>
>>> Tim
>>>
>>>
>>>
>>>
>>>
>>> --
>>> GPG me!!
>>>
>>> gpg --keyserver pool.sks-keyservers.net --recv-keys F186197B
>>>
>>>
>>> _______________________________________________
>>> varnish-misc mailing list
>>> varnish-misc at varnish-cache.org
>>> https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc
>
>
>
>
> --
> GPG me!!
>
> gpg --keyserver pool.sks-keyservers.net --recv-keys F186197B
>
>
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