feat(cloudwatch): validate parameters for a metric dimensions (closes #3116)

packages/@aws-cdk/aws-cloudwatch/README.md

@@ -58,6 +58,10 @@ const metric = new Metric({
   }
 });
 ```
+### Metric dimensions
+
+The maximum number of dimensions a Metric can have is 10. The length of a dimension name and value must be 
+between 1-255 characters in length.
 
 ### Metric Math
 

packages/@aws-cdk/aws-cloudwatch/lib/metric-types.ts

@@ -12,14 +12,14 @@ export interface IMetric {
   /**
    * Turn this metric object into an alarm configuration
    *
-   * @deprecated Use `toMetricsConfig()` instead.
+   * @deprecated Use `toMetricConfig()` instead.
    */
   toAlarmConfig(): MetricAlarmConfig;
 
   /**
    * Turn this metric object into a graph configuration
    *
-   * @deprecated Use `toMetricsConfig()` instead.
+   * @deprecated Use `toMetricConfig()` instead.
    */
   toGraphConfig(): MetricGraphConfig;
 }

packages/@aws-cdk/aws-cloudwatch/lib/metric.ts

@@ -216,7 +216,9 @@ export class Metric implements IMetric {
     if (periodSec !== 1 && periodSec !== 5 && periodSec !== 10 && periodSec !== 30 && periodSec % 60 !== 0) {
       throw new Error(`'period' must be 1, 5, 10, 30, or a multiple of 60 seconds, received ${periodSec}`);
     }
-
+    if (props.dimensions) {
+      this.validateDimensions(props.dimensions);
+    }
     this.dimensions = props.dimensions;
     this.namespace = props.namespace;
     this.metricName = props.metricName;
@@ -395,6 +397,26 @@ export class Metric implements IMetric {
 
     return list;
   }
+
+  //rules from here: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-cw-dimension.html
+  private validateDimensions(dims: DimensionHash): void {
+    if (Object.keys(dims)?.length > 10) {
+      throw new Error('The maximum number of dimensions is 10');
+    }
+
+    Object.keys(dims).sort().map(key => {
+      if (dims[key] === undefined || dims[key] === null) {
+        throw new Error(`Dimension value of '${dims[key]}' is invalid`);
+      };
+      if (key.length < 1 || key.length > 255) {
+        throw new Error(`Dimension name must be at least 1 and no more than 255 characters; received ${key}`);
+      };
+
+      if (dims[key].length < 1 || dims[key].length > 255) {
+        throw new Error(`Dimension value must be at least 1 and no more than 255 characters; received ${dims[key]}`);
+      };
+    });
+  }
 }
 
 function asString(x?: unknown): string | undefined {

packages/@aws-cdk/aws-cloudwatch/test/test.metrics.ts

@@ -51,4 +51,81 @@ export = {
 
     test.done();
   },
+
+  'cannot use null dimension value'(test: Test) {
+    test.throws(() => {
+      new Metric({
+        namespace: 'Test',
+        metricName: 'ACount',
+        period: cdk.Duration.minutes(10),
+        dimensions: {
+          DimensionWithNull: null,
+        },
+      });
+    }, /Dimension value of 'null' is invalid/);
+
+    test.done();
+  },
+
+  'cannot use undefined dimension value'(test: Test) {
+    test.throws(() => {
+      new Metric({
+        namespace: 'Test',
+        metricName: 'ACount',
+        period: cdk.Duration.minutes(10),
+        dimensions: {
+          DimensionWithUndefined: undefined,
+        },
+      });
+    }, /Dimension value of 'undefined' is invalid/);
+
+    test.done();
+  },
+
+  'cannot use long dimension values'(test: Test) {
+    const invalidDimensionValue = 'SomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValue\
+        SomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValue\
+        SomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValue\
+        SomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValue\
+        SomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValue\
+        SomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValueSomeLongValue';
+
+    test.throws(() => {
+      new Metric({
+        namespace: 'Test',
+        metricName: 'ACount',
+        period: cdk.Duration.minutes(10),
+        dimensions: {
+          DimensionWithLongValue: invalidDimensionValue,
+        },
+      });
+    }, `Dimension value must be at least 1 and no more than 255 characters; received ${invalidDimensionValue}`);
+
+    test.done();
+  },
+
+  'throws error when there are more than 10 dimensions'(test: Test) {
+    test.throws(() => {
+      new Metric({
+        namespace: 'Test',
+        metricName: 'ACount',
+        period: cdk.Duration.minutes(10),
+        dimensions: {
+          dimensionA: 'value1',
+          dimensionB: 'value2',
+          dimensionC: 'value3',
+          dimensionD: 'value4',
+          dimensionE: 'value5',
+          dimensionF: 'value6',
+          dimensionG: 'value7',
+          dimensionH: 'value8',
+          dimensionI: 'value9',
+          dimensionJ: 'value10',
+          dimensionK: 'value11',
+        },
+      } );
+    }, /The maximum number of dimensions is 10/);
+
+    test.done();
+  },
 };