bin/instrument_server in instrumental_tools-0.5.1 vs bin/instrument_server in instrumental_tools-0.5.2

@@ -33,10 +33,18 @@
       else
         raise "unsupported OS"
       end
   end
 
+  def self.command_missing(command, section)
+    puts "Command #{command} not found. Metrics for #{section} will not be collected."
+  end
+
+  def self.command_present?(command, section)
+    `which #{command}`.length > 0 || command_missing(command, section)
+  end
+
   def load_all
     self.class.memory.cycle
 
     load @platform.load_cpu
     load @platform.load_memory
@@ -48,11 +56,15 @@
     @gauges.merge!(stats[:gauges] || {})
   end
 
   module OSX
     def self.load_cpu
-      { :gauges => top }
+      output = { :gauges => {} }
+      if SystemInspector.command_present?('top', 'CPU')
+        output[:gauges].merge!(top)
+      end
+      output
     end
 
     def self.top
       lines = []
       processes = date = load = cpu = nil
@@ -82,11 +94,15 @@
       }
     end
 
     def self.load_memory
       # TODO: swap
-      { :gauges => vm_stat }
+      output = { :gauges => {} }
+      if SystemInspector.command_present?('vm_stat', 'memory')
+        output[:gauges].merge!(vm_stat)
+      end
+      output
     end
 
     def self.vm_stat
       header, *rows = `vm_stat`.split("\n")
       page_size = header.match(/page size of (\d+) bytes/)[1].to_i
@@ -106,11 +122,15 @@
       output["memory.free_percent"] = output["memory.free_mb"] / total * 100 # TODO: verify
       output
     end
 
     def self.load_disks
-      { :gauges => df }
+      output = { :gauges => {} }
+      if SystemInspector.command_present?('df', 'disk')
+        output[:gauges].merge!(df)
+      end
+      output
     end
 
     def self.df
       output = {}
       `df -k`.split("\n").grep(%r{^/dev/}).each do |line|
@@ -181,12 +201,16 @@
       }
     end
 
     def self.load_memory
       output = { :gauges => {} }
-      output[:gauges].merge!(memory)
-      output[:gauges].merge!(swap)
+      if SystemInspector.command_present?('free', 'memory')
+        output[:gauges].merge!(memory)
+      end
+      if SystemInspector.command_present?('free', 'swap')
+        output[:gauges].merge!(swap)
+      end
       output
     end
 
     def self.memory
       _, total, used, free, shared, buffers, cached = `free -k -o | grep Mem`.chomp.split(/\s+/)
@@ -207,11 +231,18 @@
         'swap.free_percent' => (free.to_f / total.to_f) * 100,
       }
     end
 
     def self.load_disks
-      { :gauges => disk_storage.merge(disk_io) }
+      output = { :gauges => {} }
+      if SystemInspector.command_present?('df', 'disk storage')
+        output[:gauges].merge!(disk_storage)
+      end
+      if SystemInspector.command_present?('mount', 'disk IO')
+        output[:gauges].merge!(disk_io)
+      end
+      output
     end
 
     def self.disk_storage
       output = {}
       `df -Pk`.split("\n").grep(%r{^/dev/}).each do |line|
@@ -250,10 +281,14 @@
       end
       output
     end
 
     def self.load_filesystem
-      { :gauges => filesystem }
+      output = { :gauges => {} }
+      if SystemInspector.command_present?('sysctl', 'filesystem')
+        output[:gauges].merge!(filesystem)
+      end
+      output
     end
 
     def self.filesystem
       allocated, unused, max = `sysctl fs.file-nr`.split[-3..-1].map { |v| v.to_i }
       open_files = allocated - unused