Cloudwatch: Refactor dimension keys resource request (#57148)

* use new layered architecture in get dimension keys request

* go lint fixes

* pr feedback

* more pr feedback

* remove not used code

* refactor route middleware

* change signature

* add integration tests for the dimension keys route

* use request suffix instead of query

* use typed args also in frontend

* remove unused import

* harmonize naming

* fix merge conflict

pkg/tsdb/cloudwatch/mocks/cloudwatch_metric_api.go

@@ -0,0 +1,58 @@
+package mocks
+
+import (
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/request"
+	"github.com/aws/aws-sdk-go/service/cloudwatch"
+	"github.com/aws/aws-sdk-go/service/cloudwatch/cloudwatchiface"
+)
+
+type FakeMetricsAPI struct {
+	cloudwatchiface.CloudWatchAPI
+	cloudwatch.GetMetricDataOutput
+
+	Metrics        []*cloudwatch.Metric
+	MetricsPerPage int
+
+	CallsGetMetricDataWithContext []*cloudwatch.GetMetricDataInput
+}
+
+func (c *FakeMetricsAPI) GetMetricDataWithContext(ctx aws.Context, input *cloudwatch.GetMetricDataInput, opts ...request.Option) (*cloudwatch.GetMetricDataOutput, error) {
+	c.CallsGetMetricDataWithContext = append(c.CallsGetMetricDataWithContext, input)
+
+	return &c.GetMetricDataOutput, nil
+}
+
+func (c *FakeMetricsAPI) ListMetricsPages(input *cloudwatch.ListMetricsInput, fn func(*cloudwatch.ListMetricsOutput, bool) bool) error {
+	if c.MetricsPerPage == 0 {
+		c.MetricsPerPage = 1000
+	}
+	chunks := chunkSlice(c.Metrics, c.MetricsPerPage)
+
+	for i, metrics := range chunks {
+		response := fn(&cloudwatch.ListMetricsOutput{
+			Metrics: metrics,
+		}, i+1 == len(chunks))
+		if !response {
+			break
+		}
+	}
+	return nil
+}
+
+func chunkSlice(slice []*cloudwatch.Metric, chunkSize int) [][]*cloudwatch.Metric {
+	var chunks [][]*cloudwatch.Metric
+	for {
+		if len(slice) == 0 {
+			break
+		}
+		if len(slice) < chunkSize {
+			chunkSize = len(slice)
+		}
+
+		chunks = append(chunks, slice[0:chunkSize])
+		slice = slice[chunkSize:]
+	}
+
+	return chunks
+}

pkg/tsdb/cloudwatch/mocks/list_metrics_service.go

@@ -0,0 +1,28 @@
+package mocks
+
+import (
+	"github.com/grafana/grafana/pkg/tsdb/cloudwatch/models"
+	"github.com/stretchr/testify/mock"
+)
+
+type ListMetricsServiceMock struct {
+	mock.Mock
+}
+
+func (a *ListMetricsServiceMock) GetDimensionKeysByDimensionFilter(*models.DimensionKeysRequest) ([]string, error) {
+	args := a.Called()
+
+	return args.Get(0).([]string), args.Error(1)
+}
+
+func (a *ListMetricsServiceMock) GetDimensionKeysByNamespace(string) ([]string, error) {
+	args := a.Called()
+
+	return args.Get(0).([]string), args.Error(1)
+}
+
+func (a *ListMetricsServiceMock) GetHardCodedDimensionKeysByNamespace(string) ([]string, error) {
+	args := a.Called()
+
+	return args.Get(0).([]string), args.Error(1)
+}

pkg/tsdb/cloudwatch/mocks/metrics_client.go

@@ -0,0 +1,15 @@
+package mocks
+
+import (
+	"github.com/aws/aws-sdk-go/service/cloudwatch"
+	"github.com/stretchr/testify/mock"
+)
+
+type FakeMetricsClient struct {
+	mock.Mock
+}
+
+func (m *FakeMetricsClient) ListMetricsWithPageLimit(params *cloudwatch.ListMetricsInput) ([]*cloudwatch.Metric, error) {
+	args := m.Called(params)
+	return args.Get(0).([]*cloudwatch.Metric), args.Error(1)
+}