feat: getting datadog api key from kubernetes secret.

Signed-off-by: Sudipto Baral <sudiptobaral.me@gmail.com>

Author: sudiptob2

metrics-operator/controllers/common/providers/datadog/datadog.go

@@ -26,6 +26,11 @@ func (d *KeptnDataDogProvider) EvaluateQuery(ctx context.Context, metric metrics
 	ctx, cancel := context.WithTimeout(ctx, 20*time.Second)
 	defer cancel()
 
+	apiKey, err := getDDSecret(ctx, provider, d.K8sClient)
+	if err != nil {
+		return "", nil, err
+	}
+
 	// TODO: get DD_API_KEY and DD_APP_KEY from kubernetes secret
 	// TODO: patch the context with the keys
 	// Ref: https://github.com/DataDog/datadog-api-client-go#getting-started
@@ -35,13 +40,19 @@ func (d *KeptnDataDogProvider) EvaluateQuery(ctx context.Context, metric metrics
 		datadog.ContextAPIKeys,
 		map[string]datadog.APIKey{
 			"apiKeyAuth": {
-				Key: "DD_API_KEY",
+				Key: apiKey,
 			},
 			"appKeyAuth": {
-				Key: "DD_APP_KEY",
+				Key: "value", // TODO: get this value from kubernetes secret.
 			},
 		},
 	)
+	ctx = context.WithValue(ctx,
+		datadog.ContextServerVariables,
+		map[string]string{
+			"site": provider.Spec.TargetServer,
+		},
+	)
 	fromTime := time.Now().AddDate(0, 0, -1)
 	queryTime := time.Now()