Cloudwatch: Refactor metrics resource request (#57424)

* refactor metrics request

* Update pkg/tsdb/cloudwatch/routes/dimension_keys_test.go

Co-authored-by: Shirley <4163034+fridgepoet@users.noreply.github.com>

* return metric struct value intead of pointer

* make it possible to test hard coded metrics service

* test all paths in route

* fix broken test

* fix one more broken test

* add integration test

Co-authored-by: Shirley <4163034+fridgepoet@users.noreply.github.com>

pkg/tsdb/cloudwatch/models/metric_types.go

@@ -7,9 +7,9 @@ import (
 
 type ListMetricsProvider interface {
 	GetDimensionKeysByDimensionFilter(*request.DimensionKeysRequest) ([]string, error)
-	GetHardCodedDimensionKeysByNamespace(string) ([]string, error)
 	GetDimensionKeysByNamespace(string) ([]string, error)
 	GetDimensionValuesByDimensionFilter(*request.DimensionValuesRequest) ([]string, error)
+	GetMetricsByNamespace(namespace string) ([]Metric, error)
 }
 
 type MetricsClientProvider interface {

pkg/tsdb/cloudwatch/models/request/dimension_keys_request.go

@@ -2,8 +2,6 @@ package request
 
 import (
 	"net/url"
-
-	"github.com/grafana/grafana/pkg/tsdb/cloudwatch/constants"
 )
 
 type DimensionKeysRequestType uint32
@@ -22,7 +20,7 @@ type DimensionKeysRequest struct {
 }
 
 func (q *DimensionKeysRequest) Type() DimensionKeysRequestType {
-	if _, exist := constants.NamespaceMetricsMap[q.Namespace]; !exist {
+	if isCustomNamespace(q.Namespace) {
 		return CustomMetricDimensionKeysRequest
 	}
 

pkg/tsdb/cloudwatch/models/request/metrics.go

@@ -0,0 +1,42 @@
+package request
+
+import (
+	"net/url"
+)
+
+type MetricsRequestType uint32
+
+const (
+	MetricsByNamespaceRequestType MetricsRequestType = iota
+	AllMetricsRequestType
+	CustomNamespaceRequestType
+)
+
+type MetricsRequest struct {
+	*ResourceRequest
+	Namespace string
+}
+
+func GetMetricsRequest(parameters url.Values) (*MetricsRequest, error) {
+	resourceRequest, err := getResourceRequest(parameters)
+	if err != nil {
+		return nil, err
+	}
+
+	return &MetricsRequest{
+		ResourceRequest: resourceRequest,
+		Namespace:       parameters.Get("namespace"),
+	}, nil
+}
+
+func (r *MetricsRequest) Type() MetricsRequestType {
+	if r.Namespace == "" {
+		return AllMetricsRequestType
+	}
+
+	if isCustomNamespace(r.Namespace) {
+		return CustomNamespaceRequestType
+	}
+
+	return MetricsByNamespaceRequestType
+}

pkg/tsdb/cloudwatch/models/request/metrics_test.go

@@ -0,0 +1,48 @@
+package request
+
+import (
+	"net/url"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestMetricsRequest(t *testing.T) {
+	t.Run("Should parse parameters", func(t *testing.T) {
+		request, err := GetMetricsRequest(map[string][]string{"region": {"us-east-1"}, "namespace": {"AWS/EC2"}})
+		require.NoError(t, err)
+		assert.Equal(t, "us-east-1", request.Region)
+		assert.Equal(t, "AWS/EC2", request.Namespace)
+	})
+
+	tests := []struct {
+		reqType MetricsRequestType
+		params  url.Values
+	}{
+		{
+			params:  map[string][]string{"region": {"us-east-1"}, "namespace": {"AWS/EC2"}},
+			reqType: MetricsByNamespaceRequestType,
+		},
+		{
+			params:  map[string][]string{"region": {"us-east-1"}},
+			reqType: AllMetricsRequestType,
+		},
+		{
+			params:  map[string][]string{"region": {"us-east-1"}, "namespace": {""}},
+			reqType: AllMetricsRequestType,
+		},
+		{
+			params:  map[string][]string{"region": {"us-east-1"}, "namespace": {"custom-namespace"}},
+			reqType: CustomNamespaceRequestType,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run("Should resolve the correct type", func(t *testing.T) {
+			request, err := GetMetricsRequest(tc.params)
+			require.NoError(t, err)
+			assert.Equal(t, tc.reqType, request.Type())
+		})
+	}
+}

pkg/tsdb/cloudwatch/models/request/utils.go

@@ -3,6 +3,8 @@ package request
 import (
 	"encoding/json"
 	"fmt"
+
+	"github.com/grafana/grafana/pkg/tsdb/cloudwatch/constants"
 )
 
 func parseDimensionFilter(dimensionFilter string) ([]*Dimension, error) {
@@ -42,3 +44,10 @@ func parseDimensionFilter(dimensionFilter string) ([]*Dimension, error) {
 
 	return dimensions, nil
 }
+
+func isCustomNamespace(namespace string) bool {
+	if _, ok := constants.NamespaceMetricsMap[namespace]; ok {
+		return false
+	}
+	return true
+}

pkg/tsdb/cloudwatch/models/types.go

@@ -34,3 +34,8 @@ type metricStatMeta struct {
 	Period int    `json:"period"`
 	Label  string `json:"label,omitempty"`
 }
+
+type Metric struct {
+	Name      string `json:"name"`
+	Namespace string `json:"namespace"`
+}