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.go

@@ -0,0 +1,46 @@
+package cloudwatch
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/cloudwatch"
+	"github.com/grafana/grafana/pkg/tsdb"
+)
+
+func (e *CloudWatchExecutor) buildMetricDataInput(queryContext *tsdb.TsdbQuery, queries map[string]*cloudWatchQuery) (*cloudwatch.GetMetricDataInput, error) {
+	startTime, err := queryContext.TimeRange.ParseFrom()
+	if err != nil {
+		return nil, err
+	}
+
+	endTime, err := queryContext.TimeRange.ParseTo()
+	if err != nil {
+		return nil, err
+	}
+
+	if !startTime.Before(endTime) {
+		return nil, fmt.Errorf("Invalid time range: Start time must be before end time")
+	}
+
+	metricDataInput := &cloudwatch.GetMetricDataInput{
+		StartTime: aws.Time(startTime),
+		EndTime:   aws.Time(endTime),
+		ScanBy:    aws.String("TimestampAscending"),
+	}
+	for _, query := range queries {
+		// 1 minutes resolution metrics is stored for 15 days, 15 * 24 * 60 = 21600
+		if query.HighResolution && (((endTime.Unix() - startTime.Unix()) / int64(query.Period)) > 21600) {
+			return nil, &queryError{errors.New("too long query period"), query.RefId}
+		}
+
+		metricDataQuery, err := e.buildMetricDataQuery(query)
+		if err != nil {
+			return nil, &queryError{err, query.RefId}
+		}
+		metricDataInput.MetricDataQueries = append(metricDataInput.MetricDataQueries, metricDataQuery)
+	}
+
+	return metricDataInput, nil
+}