Merge pull request statsd#280 from etsy/health_status

Add health status functionality, and handle SIGTERM more gracefully.

docs/admin_interface.md

@@ -11,6 +11,7 @@ available:
 * counters - a dump of all the current counters
 * gauges - a dump of all the current gauges
 * timers - a dump of the current timers
+* health - a way to set the health status of statsd
 
 The stats output currently will give you:
 
@@ -42,4 +43,8 @@ A simple nagios check can be found in the utils/ directory that can be used to
 check metric thresholds, for example the number of seconds since the last
 successful flush to graphite.
 
+The health output:
+* the health command alone allows you to see the current health status.
+* using health up or health down, you can change the current health status.
+* the healthStatus configuration option allows you to set the default health status at start.
 

exampleConfig.js

@@ -25,6 +25,7 @@ Optional Variables:
   mgmt_address:     address to run the management TCP interface on
                     [default: 0.0.0.0]
   mgmt_port:        port to run the management TCP interface on [default: 8126]
+  healthStatus:     default health status to be returned and statsd process starts ['up' or 'down', default: 'up']
   dumpMessages:     log all incoming messages
   flushInterval:    interval (in ms) to flush to Graphite
   percentThreshold: for time information, calculate the Nth percentile(s)

stats.js

@@ -22,6 +22,7 @@ var pctThreshold = null;
 var flushInterval, keyFlushInt, server, mgmtServer;
 var startup_time = Math.round(new Date().getTime() / 1000);
 var backendEvents = new events.EventEmitter();
+var healthStatus = config.healthStatus || 'up';
 
 // Load and init the backend from the backends/ directory.
 function loadBackend(config, name) {
@@ -249,7 +250,19 @@ config.configFile(process.argv[2], function (config, oldConfig) {
 
         switch(cmd) {
           case "help":
-            stream.write("Commands: stats, counters, timers, gauges, delcounters, deltimers, delgauges, quit\n\n");
+            stream.write("Commands: stats, counters, timers, gauges, delcounters, deltimers, delgauges, health, quit\n\n");
+            break;
+
+          case "health":
+            if (cmdline.length > 0) {
+              var cmdaction = cmdline[0].toLowerCase();
+              if (cmdaction === 'up') {
+                healthStatus = 'up';
+              } else if (cmdaction === 'down') {
+                healthStatus = 'down';
+              }
+            }
+            stream.write("health: " + healthStatus + "\n");
             break;
 
           case "stats":
@@ -405,3 +418,15 @@ config.configFile(process.argv[2], function (config, oldConfig) {
     }
   }
 });
+
+process.on('SIGTERM', function() {
+  if (conf.debug) {
+    util.log('Starting Final Flush');
+  }
+  healthStatus = 'down';
+  process.exit();
+});
+
+process.on('exit', function () {
+  flushMetrics();
+});