Allow piping metrics into the conversion script

README.md

@@ -64,3 +64,13 @@ When `--netcat` is used with InfluxDB output, data will be sent to port 8086. Th
 ```
 ./json2graphite.rb ~/Downloads/logdump/puppetserver/*.json --convert-to influxdb --netcat localhost --influx-db pe-metrics
 ```
+
+### Pipe data into json2graphite.rb
+
+You can pipe the output of the metrics script from pe_metric_curl_cron_jobs directly into json2graphite.rb such as:
+
+```
+/opt/puppetlabs/pe_metric_curl_cron_jobs/scripts/tk_metrics --metrics_type puppetdb | ./json2graphite.rb
+```
+
+However, you cannot pipe metrics data in and read a file in the same invocation of the script.  

json2graphite.rb

@@ -65,6 +65,10 @@ def close
 def parse_file(filename)
   data = JSON.parse(File.read(filename))
 
+  parse_input(data)
+end
+
+def parse_input( data )
   # Newer versions of the log tool insert a timestamp field into the JSON.
   if data['timestamp']
     timestamp = Time.parse(data.delete('timestamp'))
@@ -316,9 +320,17 @@ def influx_metrics(data, timestamp, parent_key = nil)
   $net_output = NetworkOutput.new(url)
 end
 
-data_files = ARGV
+data_files = []
 data_files += Dir.glob($options[:pattern]) if $options[:pattern]
 
+#http://ruby-doc.org/core-1.9.3/ARGF.html#method-i-filename
+while ARGF.filename != '-'
+  filename = ARGF.filename
+  data_files += [filename]
+  ARGF.skip
+  break if filename == ARGF.filename
+end
+
 data_files.each do |filename|
   begin
     converted_data = parse_file(filename)
@@ -333,4 +345,18 @@ def influx_metrics(data, timestamp, parent_key = nil)
   end
 end
 
+if ARGF.filename == '-'
+  begin
+    converted_data = parse_input( JSON.parse(ARGF.read) )
+
+    if $options[:host]
+      $net_output.write(converted_data)
+    else
+      STDOUT.write(converted_data)
+    end
+  rescue => e
+    STDERR.puts "ERROR: During read from STDIN: #{e.message}"
+  end
+end
+
 $net_output.close if $options[:host]