feat(cli): flush kafka queue on process exit

cli.js

@@ -6,6 +6,7 @@ const pump = require('pump')
 const fs = require('fs')
 const path = require('path')
 const pinoKafka = require('./pkafka')
+const util = require("util");
 
 function keysToDotNotation(obj, current, final) {
   if(!final) {
@@ -51,9 +52,39 @@ function start (opts) {
       process.exit(1)
     }
   }
+  const stream = pinoKafka(opts)
 
+  pump(process.stdin, stream)
 
-  pump(process.stdin, pinoKafka(opts))
+
+  function terminator( sig ) {
+    if ( typeof sig === 'string' ) {
+      flushKafkaQueue(function (err) {
+        process.exit(err ? 1 : 0);
+      });
+    }
+  }
+
+  async function flushKafkaQueue( callback ){
+    stream._kafka.flush(opts.timeout, err => {
+      if(err){
+        process.stderr.write(util.format.apply(this, err) + '\n')
+      }
+      callback(err)
+    })
+  }
+
+  ['SIGHUP', 'SIGINT', 'SIGQUIT', 'SIGILL', 'SIGTRAP', 'SIGABRT',
+    'SIGBUS', 'SIGFPE', 'SIGUSR1', 'SIGSEGV', 'SIGUSR2', 'SIGTERM'
+  ].forEach(function (sig) {
+    process.on(sig, function () {
+      try {
+        terminator(sig);
+      } catch (e) {
+        process.exit(1)
+      }
+    });
+  });
 }
 
 start(minimist(process.argv.slice(2), {