From 8aefb867c496cad91d9fed8d6dbd733c9fe23b20 Mon Sep 17 00:00:00 2001
From: Brian Palmer <brianp@instructure.com>
Date: Thu, 4 Apr 2013 10:11:17 -0600
Subject: [PATCH] optionally don't append hostname to statsd keys

test plan: add "append_hostname: false" to your statsd config and
generate statsd metrics by visiting canvas pages. no hostname should be
appended to the key, so all servers in the environment will write to the
same metric.

Change-Id: I4662601ae04661aee2a75b39eeb58c7902870a38
Reviewed-on: https://gerrit.instructure.com/19342
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
QA-Review: Clare Hetherington <clare@instructure.com>
Product-Review: Brian Palmer <brianp@instructure.com>
---
 config/statsd.yml.example      |  1 +
 lib/canvas/statsd.rb           | 15 +++++++++++++--
 spec/lib/canvas/statsd_spec.rb | 26 +++++++++++++++++++-------
 3 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/config/statsd.yml.example b/config/statsd.yml.example
index 0bcaa77956f..da9a7eb2001 100644
--- a/config/statsd.yml.example
+++ b/config/statsd.yml.example
@@ -2,3 +2,4 @@ development:
   #host: my.statsd.host
   #port: 1234
   #namespace: canvas
+  #append_hostname: false
diff --git a/lib/canvas/statsd.rb b/lib/canvas/statsd.rb
index 96cc2459c5e..91d9bf13275 100644
--- a/lib/canvas/statsd.rb
+++ b/lib/canvas/statsd.rb
@@ -29,7 +29,7 @@
 # At least a host needs to be defined for the environment, all other config is optional
 #
 # If a namespace is defined in statsd.yml, it'll be prepended to the stat name.
-# The hostname of the server will be appended to the stat name.
+# The hostname of the server will be appended to the stat name, unless `append_hostname: false` is specified in the config.
 # So if the namespace is "canvas" and the hostname is "app01", the final stat name of "my_stat" would be "stats.canvas.my_stat.app01"
 # (assuming the default statsd/graphite configuration)
 #
@@ -43,7 +43,12 @@ module Canvas::Statsd
     class_eval <<-RUBY, __FILE__, __LINE__+1
     def self.#{method}(stat, *args)
       if self.instance
-        self.instance.#{method}("\#{stat}.\#{hostname}", *args)
+        if self.append_hostname?
+          stat_name = "\#{stat}.\#{hostname}"
+        else
+          stat_name = stat.to_s
+        end
+        self.instance.#{method}(stat_name, *args)
       else
         nil
       end
@@ -55,6 +60,7 @@ module Canvas::Statsd
     start = Time.now
     result = yield
     self.timing(stat, ((Time.now - start) * 1000).round, sample_rate)
+    result
   end
 
   def self.instance
@@ -65,6 +71,7 @@ module Canvas::Statsd
         @statsd = ::Statsd.new(statsd_settings[:host])
         @statsd.port = statsd_settings[:port] if statsd_settings[:port]
         @statsd.namespace = statsd_settings[:namespace] if statsd_settings[:namespace]
+        @append_hostname = !statsd_settings.key?(:append_hostname) || !!statsd_settings[:append_hostname]
       else
         @statsd = nil
       end
@@ -72,6 +79,10 @@ module Canvas::Statsd
     @statsd
   end
 
+  def self.append_hostname?
+    @append_hostname
+  end
+
   def self.reset_instance
     remove_instance_variable(:@statsd) if defined?(@statsd)
   end
diff --git a/spec/lib/canvas/statsd_spec.rb b/spec/lib/canvas/statsd_spec.rb
index b935d735450..13d793feb25 100644
--- a/spec/lib/canvas/statsd_spec.rb
+++ b/spec/lib/canvas/statsd_spec.rb
@@ -21,16 +21,30 @@ require File.expand_path(File.dirname(__FILE__) + '/../../spec_helper.rb')
 describe "Canvas::Statsd" do
   METHODS = %w(increment decrement count gauge timing)
 
-  it "should append the hostname to stat names" do
+  it "should append the hostname to stat names by default" do
     Canvas::Statsd.stubs(:hostname).returns("testhost")
     statsd = mock()
     Canvas::Statsd.stubs(:instance).returns(statsd)
+    Canvas::Statsd.stubs(:append_hostname?).returns(true)
     METHODS.each do |method|
-      statsd.expects(method).with("test.name.testhost")
-      Canvas::Statsd.send(method, "test.name")
+      statsd.expects(method).with("test.name.testhost", "test")
+      Canvas::Statsd.send(method, "test.name", "test")
     end
     statsd.expects("timing").with("test.name.testhost", anything, anything)
-    Canvas::Statsd.time("test.name") { }
+    Canvas::Statsd.time("test.name") { "test" }.should == "test"
+  end
+
+  it "should omit hostname if specified in config" do
+    Canvas::Statsd.expects(:hostname).never
+    statsd = mock()
+    Canvas::Statsd.stubs(:instance).returns(statsd)
+    Canvas::Statsd.stubs(:append_hostname?).returns(false)
+    METHODS.each do |method|
+      statsd.expects(method).with("test.name", "test")
+      Canvas::Statsd.send(method, "test.name", "test")
+    end
+    statsd.expects("timing").with("test.name", anything, anything)
+    Canvas::Statsd.time("test.name") { "test" }.should == "test"
   end
 
   it "should ignore all calls if statsd isn't enabled" do
@@ -38,9 +52,7 @@ describe "Canvas::Statsd" do
     METHODS.each do |method|
       Canvas::Statsd.send(method, "test.name").should be_nil
     end
-    called = false
-    Canvas::Statsd.time("test.name") { called = true }.should be_nil
-    called.should == true
+    Canvas::Statsd.time("test.name") { "test" }.should == "test"
   end
 
   it "should configure a statsd instance" do