[Varnish] #1789: Disable probe, Varnish 4 continues to use it

[Varnish]

#1789: Disable probe, Varnish 4 continues to use it
--------------------+----------------------
 Reporter:  anders  |       Type:  defect
   Status:  new     |   Priority:  normal
Milestone:          |  Component:  varnishd
  Version:  4.0.3   |   Severity:  major
 Keywords:  probe   |
--------------------+----------------------
 If you have a failing probe and you want to simply disable it, Varnish
 continues to probe it using data from previous VCLs even though it is not
 present in the current VCL. The state is also preserved, so Varnish will
 respond with 503 due to "no backend connection" because of failing probes,
 when none is present in the current config.

 How to reproduce:
 1) set up a backend and a probe, with a separate probe using an url path
 that gives a failing response from the backend:

 {{{
 probe mbap_bilhold {
        .url = "/bilhold/failing_page.html";
        .interval = 5s;
        .timeout = 10s;
        .window = 5;
        .threshold = 3;
 }

 backend no000010smbap0 {
         .host = "10.111.9.10";
         .port = "8080";
         .probe = mbap_bilhold;
 }
 }}}

 2) disable the probe to try to get the site back up again:

 {{{
 #probe mbap_bilhold {
 #       .url = "/bilhold/failing_page.html";
 #       .interval = 5s;
 #       .timeout = 10s;
 #       .window = 5;
 #       .threshold = 3;
 #}

 backend no000010smbap0 {
         .host = "10.111.9.10";
         .port = "8080";
 #       .probe = mbap_bilhold;
 }
 }}}

 3) reload vcl

 4) varnishadm backend.list shows backend no000010smbap0 still being probed
 and
 failing.

 5) Site is still down, but should not! :-)

 6) Workaround: restart Varnish, site is up :-)

-- 
Ticket URL: <https://www.varnish-cache.org/trac/ticket/1789>
Varnish <https://varnish-cache.org/>
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