Cloudwatch cross account

.changelog/20541.txt

@@ -0,0 +1,3 @@
+```release-note:enhancement
+resource/aws_cloudwatch_metric_alarm: Add support for `account_id`
+```

aws/resource_aws_cloudwatch_metric_alarm.go

@@ -65,6 +65,11 @@ func resourceAwsCloudWatchMetricAlarm() *schema.Resource {
 							Required:     true,
 							ValidateFunc: validation.StringLenBetween(1, 255),
 						},
+						"account_id": {
+							Type:         schema.TypeString,
+							Optional:     true,
+							ValidateFunc: validation.StringLenBetween(1, 255),
+						},
 						"expression": {
 							Type:         schema.TypeString,
 							Optional:     true,
@@ -506,6 +511,7 @@ func flattenAwsCloudWatchMetricAlarmMetrics(metrics []*cloudwatch.MetricDataQuer
 	metricQueries := make([]map[string]interface{}, 0)
 	for _, mq := range metrics {
 		metricQuery := map[string]interface{}{
+			"account_id":  aws.StringValue(mq.AccountId),
 			"expression":  aws.StringValue(mq.Expression),
 			"id":          aws.StringValue(mq.Id),
 			"label":       aws.StringValue(mq.Label),
@@ -559,6 +565,9 @@ func expandCloudWatchMetricAlarmMetrics(v *schema.Set) []*cloudwatch.MetricDataQ
 		if v := metricQueryResource["metric"]; v != nil && len(v.([]interface{})) > 0 {
 			metricQuery.MetricStat = expandCloudWatchMetricAlarmMetricsMetric(v.([]interface{}))
 		}
+		if v, ok := metricQueryResource["account_id"]; ok && v.(string) != "" {
+			metricQuery.AccountId = aws.String(v.(string))
+		}
 		metrics = append(metrics, &metricQuery)
 	}
 	return metrics

aws/resource_aws_cloudwatch_metric_alarm_test.go

@@ -280,6 +280,13 @@ func TestAccAWSCloudWatchMetricAlarm_expression(t *testing.T) {
 					resource.TestCheckResourceAttr(resourceName, "metric_query.#", "2"),
 				),
 			},
+			{
+				Config: testAccAWSCloudWatchMetricAlarmConfigWithCrossAccountMetric(rName),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckCloudWatchMetricAlarmExists(resourceName, &alarm),
+					resource.TestCheckResourceAttrPair(resourceName, "metric_query.0.account_id", "data.aws_caller_identity.current", "account_id"),
+				),
+			},
 			{
 				Config: testAccAWSCloudWatchMetricAlarmConfigWithExpressionUpdated(rName),
 				Check: resource.ComposeTestCheckFunc(
@@ -649,6 +656,39 @@ resource "aws_cloudwatch_metric_alarm" "test" {
 `, rName)
 }
 
+func testAccAWSCloudWatchMetricAlarmConfigWithCrossAccountMetric(rName string) string {
+	return fmt.Sprintf(`
+data "aws_caller_identity" "current" {}
+
+resource "aws_cloudwatch_metric_alarm" "test" {
+  alarm_name                = "%s"
+  comparison_operator       = "GreaterThanOrEqualToThreshold"
+  evaluation_periods        = "2"
+  threshold                 = "80"
+  alarm_description         = "This metric monitors ec2 cpu utilization"
+  insufficient_data_actions = []
+
+  metric_query {
+    id          = "m1"
+    account_id  = data.aws_caller_identity.current.account_id
+    return_data = "true"
+
+    metric {
+      metric_name = "CPUUtilization"
+      namespace   = "AWS/EC2"
+      period      = "120"
+      stat        = "Average"
+      unit        = "Count"
+
+      dimensions = {
+        InstanceId = "i-abc123"
+      }
+    }
+  }
+}
+`, rName)
+}
+
 func testAccAWSCloudWatchMetricAlarmConfigWithAnomalyDetectionExpression(rName string) string {
 	return fmt.Sprintf(`
 resource "aws_cloudwatch_metric_alarm" "test" {