Make fleet status update interval configurable

[xueshanf]

Currently it is set to 5000 milliseconds in main.js. Very frequent update seems driving load high on a small t2 EC2 machine. It would be helpful to be able to configure it at docker run time.

My workaround is to change it like so:

ngconstant: {
      options: {
        name: 'config',
        dest: '<%= yeoman.dist %>/scripts/config.js',
        constants: {
          'ENVIRONMENT': 'production',
          'CACHE_VERSION': '<%= ((new Date()).valueOf().toString()) + (Math.floor((Math.random()*1000000)+1).toString()) %>',
          'STATUS_INTERVAL': '60000'
        }
...

In main controller:

angular.module('fleetuiApp')
  .controller('MainCtrl', function ($scope, $interval, machineService, unitService, STATUS_INTERVAL) {
...

$interval(getUnitsInfo,  parseInt(STATUS_INTERVAL));

And it needs a rebuild of the fleet-ui image.
It would be nice to be able to pass the STATUS_INTERVAL at docker run time.

[subicura]

Hi! This is really good idea. I'll add interval option like select tag UI. Thanks!