Improve Timeout handling and improves obscuring of DNS failure messages being swallowed by the base timeout (circuit breaker)

.gitignore

@@ -20,3 +20,5 @@ mkmf.log
 #Intellij files
 *.iml
 *.idea
+
+vendor/

CHANGELOG.md

@@ -4,6 +4,9 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This CHANGELOG follows the format listed [here](https://github.com/sensu-plugins/community/blob/master/HOW_WE_CHANGELOG.md)
 
 ## [Unreleased]
+### Changed
+- `check-http.rb`: Add options to set open-timeout and read-timeout for Net:HTTP. Improve output on what Net::HTTP timeout was encountered.
+- `check-http.rb`: Use ruby DNS resolver, and set DNS resolution timeout.
 
 ## [4.0.0] - 2018-12-17
 ### Breaking Changes

bin/check-http.rb

@@ -59,6 +59,7 @@
 require 'net/http'
 require 'net/https'
 require 'digest'
+require 'resolv-replace'
 
 #
 # Check HTTP
@@ -165,7 +166,19 @@ class CheckHttp < Sensu::Plugin::Check::CLI
          short: '-t SECS',
          long: '--timeout SECS',
          proc: proc(&:to_i),
-         description: 'Set the timeout',
+         description: 'Set the total execution timeout in seconds',
+         default: 15
+
+  option :open_timeout,
+         long: '--open-timeout SECS',
+         proc: proc(&:to_i),
+         description: 'Number of seconds to wait for the connection to open',
+         default: 15
+
+  option :read_timeout,
+         long: '--read-timeout SECS',
+         proc: proc(&:to_i),
+         description: 'Number of seconds to wait for one block to be read',
          default: 15
 
   option :redirectok,
@@ -250,10 +263,19 @@ def run
       config[:port] ||= config[:ssl] ? 443 : 80
     end
 
+    # Use Ruby DNS Resolver and set DNS resolution timeout to 800ms
+    dns_resolver = Resolv::DNS.new
+    dns_resolver.timeouts = 0.8
+    Resolv::DefaultResolver.replace_resolvers([dns_resolver])
+
     begin
       Timeout.timeout(config[:timeout]) do
         acquire_resource
       end
+    rescue Net::OpenTimeout
+      critical 'Request timed out opening connection'
+    rescue Net::ReadTimeout
+      critical 'Request timed out reading data'
     rescue Timeout::Error
       critical 'Request timed out'
     rescue StandardError => e
@@ -279,8 +301,8 @@ def acquire_resource
     else
       http = Net::HTTP.new(config[:host], config[:port])
     end
-    http.read_timeout = config[:timeout]
-    http.open_timeout = config[:timeout]
+    http.read_timeout = config[:read_timeout]
+    http.open_timeout = config[:open_timeout]
     http.ssl_timeout = config[:timeout]
     http.continue_timeout = config[:timeout]
     http.keep_alive_timeout = config[:timeout]