feat: Add region and account parameters as optional global defaults (#311)

This lets me create cross-account and cross-region monitoring. Currently only the current account is supported.

My PR adds these parameters at the *global level* because I didn't want to go through every resource and add these extra parameters. This creates a limitation where an instance of `MonitoringFacade` would refer only to those specific region/accounts.

This is good enough for me though, so please advise if it's not desired.

---

_By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license_

Author: edisongustavo

API.md

@@ -30,6 +30,21 @@ export interface MetricFactoryDefaults {
    * @default - DefaultMetricPeriod
    */
   readonly period?: Duration;
+
+  /**
+   * Region where the metrics exist.
+   *
+   * @default The region configured by the construct holding the Monitoring construct
+   * @see https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/Cross-Account-Cross-Region.html
+   */
+  readonly region?: string;
+  /**
+   * Account where the metrics exist.
+   *
+   * @default The account configured by the construct holding the Monitoring construct
+   * @see https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/Cross-Account-Cross-Region.html
+   */
+  readonly account?: string;
 }
 
 export interface MetricFactoryProps {
@@ -56,6 +71,8 @@ export class MetricFactory {
    * @param color metric color; if undefined, uses a CloudWatch provided color (preferred)
    * @param namespace specify a custom namespace; if undefined, uses the global default
    * @param period specify a custom period; if undefined, uses the global default
+   * @param region specify a custom region; if undefined, uses the global default
+   * @param account specify a custom account; if undefined, uses the global default
    */
   createMetric(
     metricName: string,
@@ -64,7 +81,9 @@ export class MetricFactory {
     dimensionsMap?: DimensionsMap,
     color?: string,
     namespace?: string,
-    period?: Duration
+    period?: Duration,
+    region?: string,
+    account?: string
   ): MetricWithAlarmSupport {
     return new Metric({
       statistic,
@@ -76,6 +95,8 @@ export class MetricFactory {
         : undefined,
       namespace: this.getNamespaceWithFallback(namespace),
       period: period ?? this.globalDefaults.period ?? DefaultMetricPeriod,
+      region: region ?? this.globalDefaults.region,
+      account: account ?? this.globalDefaults.account,
     });
   }
 

lib/common/metric/MetricFactory.ts

@@ -1,7 +1,9 @@
+import { Duration } from "aws-cdk-lib";
 import { Metric } from "aws-cdk-lib/aws-cloudwatch";
 
 import {
   MetricFactory,
+  MetricFactoryDefaults,
   MetricStatistic,
   RateComputationMethod,
 } from "../../../lib";
@@ -19,6 +21,41 @@ test("createMetric without global namespace throws an error", () => {
   ).toThrowError();
 });
 
+test("snapshot test: global defaults", () => {
+  function testMetric(props: MetricFactoryDefaults) {
+    const metricFactory = new MetricFactory({
+      globalDefaults: {
+        namespace: "DummyNamespace",
+        ...props,
+      },
+    });
+    const metric = metricFactory.createMetric(
+      "DummyMetricName",
+      MetricStatistic.P90
+    );
+    expect(metric).toMatchSnapshot();
+  }
+
+  testMetric({
+    namespace: "SomeNamespace",
+  });
+  testMetric({
+    period: Duration.minutes(15),
+  });
+  testMetric({
+    region: "us-west-2",
+  });
+  testMetric({
+    account: "123456789",
+  });
+  testMetric({
+    namespace: "SomeNamespace",
+    period: Duration.minutes(15),
+    region: "us-west-2",
+    account: "123456789",
+  });
+});
+
 test("snapshot test: createMetric", () => {
   const metricFactory = new MetricFactory({
     globalDefaults: {
@@ -53,7 +90,10 @@ test("snapshot test: createMetric", () => {
       AnotherDummyDimension: undefined as unknown as string,
     },
     DummyColor,
-    "DummyNamespaceOverride"
+    "DummyNamespaceOverride",
+    Duration.minutes(15),
+    "us-west-2",
+    "123456789"
   );
 
   expect(metricWithUndefinedDimensions).toMatchSnapshot();