feat: handle cross-account/region for metric math, search, and anomaly detection in MetricFactory (#415)

This expands on what was implemented in #311, which only handled regular metrics via `createMetric`.

---

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

Author: Eugene Cheung

API.md

@@ -108,20 +108,26 @@ export class MetricFactory {
    * @param label metric label (required, as there is no reasonable default)
    * @param color metric color; if undefined, uses a CloudWatch provided color (preferred)
    * @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
    */
   createMetricMath(
     expression: string,
     usingMetrics: Record<string, IMetric>,
     label: string,
     color?: string,
-    period?: Duration
+    period?: Duration,
+    region?: string,
+    account?: string
   ): MetricWithAlarmSupport {
     return new MathExpression({
       label,
       color,
       expression,
       usingMetrics,
       period: period ?? this.globalDefaults.period ?? DefaultMetricPeriod,
+      searchRegion: region ?? this.globalDefaults.region,
+      searchAccount: account ?? this.globalDefaults.account,
     });
   }
 
@@ -136,14 +142,18 @@ export class MetricFactory {
    * @param namespace specify a custom namespace; if undefined, uses the global default
    * @param label specify custom label for search metrics; default is " " as it cannot be empty string
    * @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
    */
   createMetricSearch(
     query: string,
     dimensionsMap: DimensionsMap,
     statistic: MetricStatistic,
     namespace?: string,
     label?: string,
-    period?: Duration
+    period?: Duration,
+    region?: string,
+    account?: string
   ): IMetric {
     const finalPeriod =
       period ?? this.globalDefaults.period ?? DefaultMetricPeriod;
@@ -169,6 +179,8 @@ export class MetricFactory {
       // cannot be an empty string and undefined is no good either
       label: label ?? " ",
       period: finalPeriod,
+      searchRegion: region ?? this.globalDefaults.region,
+      searchAccount: account ?? this.globalDefaults.account,
     });
   }
 
@@ -185,14 +197,18 @@ export class MetricFactory {
    * @param color metric color; if undefined, uses a CloudWatch provided color (preferred)
    * @param expressionId expression ID of the metric; uses `m1` if undefined
    * @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
    */
   createMetricAnomalyDetection(
     metric: IMetric,
     stdev: number,
     label: string,
     color?: string,
     expressionId?: string,
-    period?: Duration
+    period?: Duration,
+    region?: string,
+    account?: string
   ): MetricWithAlarmSupport {
     const finalExpressionId = expressionId ?? "m1";
     const usingMetrics: Record<string, IMetric> = {};
@@ -203,6 +219,8 @@ export class MetricFactory {
       usingMetrics,
       expression: `ANOMALY_DETECTION_BAND(${finalExpressionId},${stdev})`,
       period: period ?? this.globalDefaults.period ?? DefaultMetricPeriod,
+      searchRegion: region ?? this.globalDefaults.region,
+      searchAccount: account ?? this.globalDefaults.account,
     });
   }
 

lib/common/metric/MetricFactory.ts

@@ -28,9 +28,12 @@ export interface XaxrMathExpressionProps extends MathExpressionProps {
   readonly region?: string;
 }
 
+// TODO: remove this as a breaking change
 /**
  * Custom wrapper class for MathExpression that supports account and region specification.
  * @see https://github.com/aws/aws-cdk/issues/9039
+ *
+ * @deprecated Use MathExpression from aws-cdk-lib/aws-cloudwatch instead.
  */
 export class XaxrMathExpression implements IMetric {
   private props: XaxrMathExpressionProps;
@@ -41,22 +44,22 @@ export class XaxrMathExpression implements IMetric {
     this.mathExpression = new MathExpression(props);
   }
 
+  /**
+   * @deprecated Use MathExpression from aws-cdk-lib/aws-cloudwatch instead.
+   */
   with(options: MathExpressionOptions): IMetric {
-    return new XaxrMathExpression({
+    return new MathExpression({
       ...this.props,
       ...options,
+      searchAccount: this.props.account,
+      searchRegion: this.props.region,
     });
   }
 
+  /**
+   * @deprecated Use MathExpression from aws-cdk-lib/aws-cloudwatch instead.
+   */
   toMetricConfig(): MetricConfig {
-    const defaultMetricConfig = this.mathExpression.toMetricConfig();
-    return {
-      ...defaultMetricConfig,
-      renderingProperties: {
-        ...defaultMetricConfig.renderingProperties,
-        accountId: this.props.account,
-        region: this.props.region,
-      },
-    };
+    return this.mathExpression.toMetricConfig();
   }
 }

lib/common/metric/XaxrMathExpression.ts

@@ -1,11 +1,7 @@
 import { Duration } from "aws-cdk-lib";
-import { IMetric, Metric } from "aws-cdk-lib/aws-cloudwatch";
+import { IMetric, MathExpression, Metric } from "aws-cdk-lib/aws-cloudwatch";
 
-import {
-  MetricStatistic,
-  MetricWithAlarmSupport,
-  XaxrMathExpression,
-} from "../../common";
+import { MetricStatistic, MetricWithAlarmSupport } from "../../common";
 
 export const BillingRegion = "us-east-1";
 export const BillingCurrency = "USD";
@@ -17,20 +13,17 @@ const DefaultServiceLimit = 10;
 
 export class BillingMetricFactory {
   metricSearchTopCostByServiceInUsd(): IMetric {
-    // standard MathExpression class does not support region
-    // TODO: revisit after migration to CDK 1.126.0
-
-    const search = new XaxrMathExpression({
+    const search = new MathExpression({
       period: BillingPeriod,
-      region: BillingRegion,
+      searchRegion: BillingRegion,
       expression: `SEARCH('{${BillingNamespace},Currency,ServiceName} MetricName="${BillingMetric}"', 'Maximum', ${BillingPeriod.toSeconds()})`,
       usingMetrics: {},
       label: " ",
     });
 
-    return new XaxrMathExpression({
+    return new MathExpression({
       period: BillingPeriod,
-      region: BillingRegion,
+      searchRegion: BillingRegion,
       expression: `SORT(search, MAX, DESC, ${DefaultServiceLimit})`,
       usingMetrics: { search },
       label: " ",