CloudWatch: Datasource improvements (#20268)

* CloudWatch: Datasource improvements

* Add statistic as template variale

* Add wildcard to list of values

* Template variable intercept dimension key

* Return row specific errors when transformation error occured

* Add meta feedback

* Make it possible to retrieve values without known metrics

* Add curated dashboard for EC2

* Fix broken tests

* Use correct dashboard name

* Display alert in case multi template var is being used for some certain props in the cloudwatch query

* Minor fixes after feedback

* Update dashboard json

* Update snapshot test

* Make sure region default is intercepted in cloudwatch link

* Update dashboards

* Include ec2 dashboard in ds

* Do not include ec2 dashboard in beta1

* Display actual region

pkg/tsdb/cloudwatch/metric_data_input_builder_test.go

@@ -0,0 +1,28 @@
+package cloudwatch
+
+import (
+	"testing"
+
+	"github.com/grafana/grafana/pkg/tsdb"
+
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestMetricDataInputBuilder(t *testing.T) {
+	Convey("TestMetricDataInputBuilder", t, func() {
+		executor := &CloudWatchExecutor{}
+		query := make(map[string]*cloudWatchQuery)
+
+		Convey("Time range is valid", func() {
+			Convey("End time before start time should result in error", func() {
+				_, err := executor.buildMetricDataInput(&tsdb.TsdbQuery{TimeRange: tsdb.NewTimeRange("now-1h", "now-2h")}, query)
+				So(err.Error(), ShouldEqual, "Invalid time range: Start time must be before end time")
+			})
+
+			Convey("End time equals start time should result in error", func() {
+				_, err := executor.buildMetricDataInput(&tsdb.TsdbQuery{TimeRange: tsdb.NewTimeRange("now-1h", "now-1h")}, query)
+				So(err.Error(), ShouldEqual, "Invalid time range: Start time must be before end time")
+			})
+		})
+	})
+}