Fix Prometheus test connection

docs/sources/index.md

@@ -10,7 +10,7 @@ It provides a powerful and elegant way to create, share, and explore data and da
 
 Grafana is most commonly used for Internet infrastructure and application analytics, but many use it in other domains including industrial sensors, home automation, weather, and process control.
 
-Grafana features pluggable panels and data sources allowing easy extensibility. There is currently rich support for [Graphite](http://graphite.readthedocs.org/en/latest/), [InfluxDB](http://influxdb.org) and [OpenTSDB](http://opentsdb.net). There is also experimental support for [KairosDB](https://github.com/kairosdb/kairosdb), and SQL is on the roadmap. Grafana has a variety of panels, including a fully featured graph panel with rich visualization options.
+Grafana features pluggable panels and data sources allowing easy extensibility. There is currently rich support for [Graphite](http://graphite.readthedocs.org/en/latest/), [InfluxDB](http://influxdb.org) and [OpenTSDB](http://opentsdb.net). There is also experimental support for [KairosDB](https://github.com/kairosdb/kairosdb), [Prometheus](http://prometheus.io/), and SQL is on the roadmap. Grafana has a variety of panels, including a fully featured graph panel with rich visualization options.
 
 Version 2.0 was released in April 2015: Grafana now ships with its own backend server that brings [many changes and features](../guides/whats-new-in-v2/).    
 Version 2.1 was released in July 2015 and added [even more features and enhancements](../guides/whats-new-in-v2-1/).

public/app/plugins/datasource/prometheus/datasource.js

@@ -212,7 +212,7 @@ function (angular, _, moment, dateMath) {
     };
 
     PrometheusDatasource.prototype.testDatasource = function() {
-      return this.metricFindQuery('*').then(function() {
+      return this.metricFindQuery('metrics(.*)').then(function() {
         return { status: 'success', message: 'Data source is working', title: 'Success' };
       });
     };