feat(cloudwatch): EC2 actions (aws#13281)

Fixes aws#13228
----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

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

@@ -11,4 +11,19 @@
 
 This library contains a set of classes which can be used as CloudWatch Alarm actions.
 
+The currently implemented actions are: EC2 Actions, SNS Actions, Autoscaling Actions and Aplication Autoscaling Actions
+
+
+## EC2 Action Example
+
+```ts
+import * as cw from "@aws-cdk/aws-cloudwatch";
+// Alarm must be configured with an EC2 per-instance metric
+let alarm: cw.Alarm;
+// Attach a reboot when alarm triggers
+alarm.addAlarmAction(
+  new Ec2Action(Ec2InstanceActions.REBOOT)
+);
+```
+
 See `@aws-cdk/aws-cloudwatch` for more information.

packages/@aws-cdk/aws-cloudwatch-actions/lib/ec2.ts

@@ -0,0 +1,47 @@
+import * as cloudwatch from '@aws-cdk/aws-cloudwatch';
+import { Stack } from '@aws-cdk/core';
+
+// keep this import separate from other imports to reduce chance for merge conflicts with v2-main
+// eslint-disable-next-line no-duplicate-imports, import/order
+import { Construct } from '@aws-cdk/core';
+
+/**
+ * Types of EC2 actions available
+ */
+export enum Ec2InstanceAction {
+  /**
+   * Stop the instance
+   */
+  STOP = 'stop',
+  /**
+   * Terminatethe instance
+   */
+  TERMINATE = 'terminate',
+  /**
+   * Recover the instance
+   */
+  RECOVER = 'recover',
+  /**
+   * Reboot the instance
+   */
+  REBOOT = 'reboot'
+}
+
+/**
+ * Use an EC2 action as an Alarm action
+ */
+export class Ec2Action implements cloudwatch.IAlarmAction {
+  private ec2Action: Ec2InstanceAction;
+
+  constructor(instanceAction: Ec2InstanceAction) {
+    this.ec2Action = instanceAction;
+  }
+
+  /**
+   * Returns an alarm action configuration to use an EC2 action as an alarm action
+   */
+  bind(_scope: Construct, _alarm: cloudwatch.IAlarm): cloudwatch.AlarmActionConfig {
+    return { alarmActionArn: `arn:aws:automate:${Stack.of(_scope).region}:ec2:${this.ec2Action}` };
+  }
+}
+

packages/@aws-cdk/aws-cloudwatch-actions/lib/index.ts

@@ -1,3 +1,4 @@
 export * from './appscaling';
 export * from './autoscaling';
 export * from './sns';
+export * from './ec2';

packages/@aws-cdk/aws-cloudwatch-actions/test/ec2.test.ts

@@ -0,0 +1,41 @@
+import '@aws-cdk/assert/jest';
+import * as cloudwatch from '@aws-cdk/aws-cloudwatch';
+import { Stack } from '@aws-cdk/core';
+import * as actions from '../lib';
+
+test('can use instance reboot as alarm action', () => {
+  // GIVEN
+  const stack = new Stack();
+  const alarm = new cloudwatch.Alarm(stack, 'Alarm', {
+    metric: new cloudwatch.Metric({
+      namespace: 'AWS/EC2',
+      metricName: 'StatusCheckFailed',
+      dimensions: {
+        InstanceId: 'i-03cb889aaaafffeee',
+      },
+    }),
+    evaluationPeriods: 3,
+    threshold: 100,
+  });
+
+  // WHEN
+  alarm.addAlarmAction(new actions.Ec2Action(actions.Ec2InstanceAction.REBOOT));
+
+  // THEN
+  expect(stack).toHaveResource('AWS::CloudWatch::Alarm', {
+    AlarmActions: [
+      {
+        'Fn::Join': [
+          '',
+          [
+            'arn:aws:automate:',
+            {
+              Ref: 'AWS::Region',
+            },
+            ':ec2:reboot',
+          ],
+        ],
+      },
+    ],
+  });
+});

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

@@ -1,5 +1,6 @@
 import { Lazy, Stack, Token } from '@aws-cdk/core';
 import { Construct } from 'constructs';
+import { IAlarmAction } from './alarm-action';
 import { AlarmBase, IAlarm } from './alarm-base';
 import { CfnAlarm, CfnAlarmProps } from './cloudwatch.generated';
 import { HorizontalAnnotation } from './graph';
@@ -224,6 +225,33 @@ export class Alarm extends AlarmBase {
     return this.annotation;
   }
 
+  /**
+   * Trigger this action if the alarm fires
+   *
+   * Typically the ARN of an SNS topic or ARN of an AutoScaling policy.
+   */
+  public addAlarmAction(...actions: IAlarmAction[]) {
+    if (this.alarmActionArns === undefined) {
+      this.alarmActionArns = [];
+    }
+
+    this.alarmActionArns.push(...actions.map(a =>
+      this.validateActionArn(a.bind(this, this).alarmActionArn),
+    ));
+  }
+
+  private validateActionArn(actionArn: string): string {
+    const ec2ActionsRegexp: RegExp = /arn:aws:automate:[a-z|\d|-]+:ec2:[a-z]+/;
+    if (ec2ActionsRegexp.test(actionArn)) {
+      // Check per-instance metric
+      const metricConfig = this.metric.toMetricConfig();
+      if (metricConfig.metricStat?.dimensions?.length != 1 || metricConfig.metricStat?.dimensions![0].name != 'InstanceId') {
+        throw new Error(`EC2 alarm actions requires an EC2 Per-Instance Metric. (${JSON.stringify(metricConfig)} does not have an 'InstanceId' dimension)`);
+      }
+    }
+    return actionArn;
+  }
+
   private renderMetric(metric: IMetric) {
     const self = this;
     return dispatchMetric(metric, {

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

@@ -42,6 +42,20 @@ export = {
 
     test.done();
   },
+  'non ec2 instance related alarm does not accept EC2 action'(test: Test) {
+
+    const stack = new Stack();
+    const alarm = new Alarm(stack, 'Alarm', {
+      metric: testMetric,
+      threshold: 1000,
+      evaluationPeriods: 2,
+    });
+
+    test.throws(() => {
+      alarm.addAlarmAction(new Ec2TestAlarmAction('arn:aws:automate:us-east-1:ec2:reboot'));
+    }, /EC2 alarm actions requires an EC2 Per-Instance Metric. \(.+ does not have an 'InstanceId' dimension\)/);
+    test.done();
+  },
   'can make simple alarm'(test: Test) {
     // GIVEN
     const stack = new Stack();
@@ -253,3 +267,12 @@ class TestAlarmAction implements IAlarmAction {
     return { alarmActionArn: this.arn };
   }
 }
+
+class Ec2TestAlarmAction implements IAlarmAction {
+  constructor(private readonly arn: string) {
+  }
+
+  public bind(_scope: Construct, _alarm: IAlarm) {
+    return { alarmActionArn: this.arn };
+  }
+}