feat(cloudwatch): dashboardName validation (#3382)

Fixes #2976

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

@@ -1,4 +1,4 @@
-import { Construct, Lazy, Resource, Stack } from "@aws-cdk/core";
+import { Construct, Lazy, Resource, Stack, Token } from "@aws-cdk/core";
 import { CfnDashboard } from './cloudwatch.generated';
 import { Column, Row } from "./layout";
 import { IWidget } from "./widget";
@@ -10,9 +10,11 @@ export enum PeriodOverride {
 
 export interface DashboardProps {
   /**
-   * Name of the dashboard
+   * Name of the dashboard.
    *
-   * @default Automatically generated name
+   * If set, must only contain alphanumerics, dash (-) and underscore (_)
+   *
+   * @default - automatically generated name
    */
   readonly dashboardName?: string;
 
@@ -67,6 +69,16 @@ export class Dashboard extends Resource {
       physicalName: props.dashboardName,
     });
 
+    {
+      const {dashboardName} = props;
+      if (dashboardName && !Token.isUnresolved(dashboardName) && !dashboardName.match(/^[\w-]+$/)) {
+        throw new Error([
+          `The value ${dashboardName} for field dashboardName contains invalid characters.`,
+          'It can only contain alphanumerics, dash (-) and underscore (_).'
+        ].join(' '));
+      }
+    }
+
     new CfnDashboard(this, 'Resource', {
       dashboardName: this.physicalName,
       dashboardBody: Lazy.stringValue({ produce: () => {

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

@@ -149,6 +149,24 @@ export = {
     // THEN
     expect(stack).to(haveResource('AWS::CloudWatch::Dashboard', {}));
 
+    test.done();
+  },
+
+  'throws if DashboardName is not valid'(test: Test) {
+    // GIVEN
+    const app = new App();
+    const stack = new Stack(app, 'MyStack');
+
+    // WHEN
+    const toThrow = () => {
+      new Dashboard(stack, 'MyDashboard', {
+        dashboardName: 'My Invalid Dashboard Name',
+      });
+    };
+
+    // THEN
+    test.throws(() => toThrow(), /field dashboardName contains invalid characters/);
+
     test.done();
   }
 };