errors

Catching a failed call

By default, a call that fails stops the collector, in the state its failure gives. errors=$err lets the collector decide: here, a site that refuses or does not answer is said down, critical, rather than unreachable.

How to read it

• http.get($url, errors=$err): the call fills $err whatever happens, array('code' => …, 'text' => …, 'details' => …); on success, code and text are ''.
• On a failure caught so, the call returns '' and the collector goes on: test $err['code'] != '' before reading the answer. Reading $answer['status'] of a failed call stops the collector.
• The codes are fixed: timeout, connection_refused, host_unknown, network_error, access_denied… The text is for people, never to test.
• errors= never catches a refusal of the connection checks set in the tree (a certificate, a fingerprint, the TLS profile): those always stop the collector, misconfigured.
• There is no try and no catch: errors= covers its own call only.

To adapt it

• errors= exists on every protocol call: ssh.run, snmp.get, ntp.time, winrm.run…