feat(iot): add Action to republish MQTT messages to another MQTT topic

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

@@ -21,6 +21,7 @@ supported AWS Services. Instances of these classes should be passed to
 
 Currently supported are:
 
+- Republish a message to another MQTT topic
 - Invoke a Lambda function
 - Put objects to a S3 bucket
 - Put logs to CloudWatch Logs
@@ -30,6 +31,22 @@ Currently supported are:
 - Put records to Kinesis Data Firehose stream
 - Send messages to SQS queues
 
+## Republish a message to another MQTT topic
+
+The code snippet below creates an AWS IoT Rule that republish a message to
+another MQTT topic when it is triggered.
+
+```ts
+new iot.TopicRule(this, 'TopicRule', {
+  sql: iot.IotSql.fromStringAsVer20160323("SELECT topic(2) as device_id, timestamp() as timestamp, temperature FROM 'device/+/data'"),
+  actions: [
+    new actions.IotRepublishMqttAction('${topic()}/republish', {
+      qos: actions.MqttQualityOfService.AT_LEAST_ONCE, // optional property, default is MqttQualityOfService.ZERO_OR_MORE_TIMES
+    }),
+  ],
+});
+```
+
 ## Invoke a Lambda function
 
 The code snippet below creates an AWS IoT Rule that invoke a Lambda function

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

@@ -3,6 +3,7 @@ export * from './cloudwatch-put-metric-action';
 export * from './cloudwatch-set-alarm-state-action';
 export * from './common-action-props';
 export * from './firehose-put-record-action';
+export * from './iot-republish-action';
 export * from './kinesis-put-record-action';
 export * from './lambda-function-action';
 export * from './s3-put-object-action';

packages/@aws-cdk/aws-iot-actions/lib/iot-republish-action.ts

@@ -0,0 +1,72 @@
+import * as iam from '@aws-cdk/aws-iam';
+import * as iot from '@aws-cdk/aws-iot';
+import { CommonActionProps } from './common-action-props';
+import { singletonActionRole } from './private/role';
+
+/**
+ * MQTT Quality of Service (QoS) indicates the level of assurance for delivery of an MQTT Message.
+ *
+ * @see https://docs.aws.amazon.com/iot/latest/developerguide/mqtt.html#mqtt-qos
+ */
+export enum MqttQualityOfService {
+  /**
+   * QoS level 0. Sent zero or more times.
+   * This level should be used for messages that are sent over reliable communication links or that can be missed without a problem.
+   */
+  ZERO_OR_MORE_TIMES,
+
+  /**
+   * QoS level 1. Sent at least one time, and then repeatedly until a PUBACK response is received.
+   * The message is not considered complete until the sender receives a PUBACK response to indicate successful delivery.
+   */
+  AT_LEAST_ONCE,
+}
+
+/**
+ * Configuration properties of an action to republish MQTT messages.
+ */
+export interface IotRepublishMqttActionProps extends CommonActionProps {
+  /**
+   * The Quality of Service (QoS) level to use when republishing messages.
+   *
+   * @see https://docs.aws.amazon.com/iot/latest/developerguide/mqtt.html#mqtt-qos
+   *
+   * @default MqttQualityOfService.ZERO_OR_MORE_TIMES
+   */
+  readonly qos?: MqttQualityOfService;
+}
+
+/**
+ * The action to put the record from an MQTT message to republish another MQTT topic.
+ */
+export class IotRepublishMqttAction implements iot.IAction {
+  private readonly qos?: MqttQualityOfService;
+  private readonly role?: iam.IRole;
+
+  /**
+   * @param topic The MQTT topic to which to republish the message.
+   * @param props Optional properties to not use default.
+   */
+  constructor(private readonly topic: string, props: IotRepublishMqttActionProps = {}) {
+    this.qos = props.qos;
+    this.role = props.role;
+  }
+
+  bind(rule: iot.ITopicRule): iot.ActionConfig {
+    const role = this.role ?? singletonActionRole(rule);
+    role.addToPrincipalPolicy(new iam.PolicyStatement({
+      actions: ['iot:Publish'],
+      resources: ['*'],
+    }));
+
+    return {
+      configuration: {
+        republish: {
+          topic: this.topic,
+          qos: this.qos,
+          roleArn: role.roleArn,
+        },
+      },
+    };
+  }
+}

packages/@aws-cdk/aws-iot-actions/test/iot/integ.iot-republish-action.expected.json

@@ -0,0 +1,65 @@
+{
+  "Resources": {
+    "TopicRule40A4EA44": {
+      "Type": "AWS::IoT::TopicRule",
+      "Properties": {
+        "TopicRulePayload": {
+          "Actions": [
+            {
+              "Republish": {
+                "Qos": 1,
+                "RoleArn": {
+                  "Fn::GetAtt": [
+                    "TopicRuleTopicRuleActionRole246C4F77",
+                    "Arn"
+                  ]
+                },
+                "Topic": "${topic()}/republish"
+              }
+            }
+          ],
+          "AwsIotSqlVersion": "2016-03-23",
+          "Sql": "SELECT * FROM 'device/+/data'"
+        }
+      }
+    },
+    "TopicRuleTopicRuleActionRole246C4F77": {
+      "Type": "AWS::IAM::Role",
+      "Properties": {
+        "AssumeRolePolicyDocument": {
+          "Statement": [
+            {
+              "Action": "sts:AssumeRole",
+              "Effect": "Allow",
+              "Principal": {
+                "Service": "iot.amazonaws.com"
+              }
+            }
+          ],
+          "Version": "2012-10-17"
+        }
+      }
+    },
+    "TopicRuleTopicRuleActionRoleDefaultPolicy99ADD687": {
+      "Type": "AWS::IAM::Policy",
+      "Properties": {
+        "PolicyDocument": {
+          "Statement": [
+            {
+              "Action": "iot:Publish",
+              "Effect": "Allow",
+              "Resource": "*"
+            }
+          ],
+          "Version": "2012-10-17"
+        },
+        "PolicyName": "TopicRuleTopicRuleActionRoleDefaultPolicy99ADD687",
+        "Roles": [
+          {
+            "Ref": "TopicRuleTopicRuleActionRole246C4F77"
+          }
+        ]
+      }
+    }
+  }
+}

packages/@aws-cdk/aws-iot-actions/test/iot/integ.iot-republish-action.ts

@@ -0,0 +1,25 @@
+import * as iot from '@aws-cdk/aws-iot';
+import * as cdk from '@aws-cdk/core';
+import * as actions from '../../lib';
+
+class TestStack extends cdk.Stack {
+  constructor(scope: cdk.App, id: string, props?: cdk.StackProps) {
+    super(scope, id, props);
+
+    const topicRule = new iot.TopicRule(this, 'TopicRule', {
+      sql: iot.IotSql.fromStringAsVer20160323(
+        "SELECT * FROM 'device/+/data'",
+      ),
+    });
+
+    topicRule.addAction(
+      new actions.IotRepublishMqttAction('${topic()}/republish', {
+        qos: actions.MqttQualityOfService.AT_LEAST_ONCE,
+      }),
+    );
+  }
+}
+
+const app = new cdk.App();
+new TestStack(app, 'iot-republish-action-test-stack');
+app.synth();

packages/@aws-cdk/aws-iot-actions/test/iot/iot-republish-action.test.ts

@@ -0,0 +1,107 @@
+import { Template, Match } from '@aws-cdk/assertions';
+import * as iam from '@aws-cdk/aws-iam';
+import * as iot from '@aws-cdk/aws-iot';
+import * as cdk from '@aws-cdk/core';
+import * as actions from '../../lib';
+
+let stack: cdk.Stack;
+let topicRule:iot.TopicRule;
+beforeEach(() => {
+  stack = new cdk.Stack();
+  topicRule = new iot.TopicRule(stack, 'MyTopicRule', {
+    sql: iot.IotSql.fromStringAsVer20160323("SELECT topic(2) as device_id FROM 'device/+/data'"),
+  });
+});
+
+test('Default IoT republish action', () => {
+  // WHEN
+  topicRule.addAction(
+    new actions.IotRepublishMqttAction('test-topic'),
+  );
+
+  // THEN
+  Template.fromStack(stack).hasResourceProperties('AWS::IoT::TopicRule', {
+    TopicRulePayload: {
+      Actions: [
+        {
+          Republish: {
+            Topic: 'test-topic',
+            RoleArn: {
+              'Fn::GetAtt': ['MyTopicRuleTopicRuleActionRoleCE2D05DA', 'Arn'],
+            },
+          },
+        },
+      ],
+    },
+  });
+
+  Template.fromStack(stack).hasResourceProperties('AWS::IAM::Role', {
+    AssumeRolePolicyDocument: {
+      Statement: [
+        {
+          Action: 'sts:AssumeRole',
+          Effect: 'Allow',
+          Principal: {
+            Service: 'iot.amazonaws.com',
+          },
+        },
+      ],
+      Version: '2012-10-17',
+    },
+  });
+
+  Template.fromStack(stack).hasResourceProperties('AWS::IAM::Policy', {
+    PolicyDocument: {
+      Statement: [
+        {
+          Action: 'iot:Publish',
+          Effect: 'Allow',
+          Resource: '*',
+        },
+      ],
+      Version: '2012-10-17',
+    },
+    PolicyName: 'MyTopicRuleTopicRuleActionRoleDefaultPolicy54A701F7',
+    Roles: [
+      { Ref: 'MyTopicRuleTopicRuleActionRoleCE2D05DA' },
+    ],
+  });
+});
+
+test('can set qos', () => {
+  // WHEN
+  topicRule.addAction(
+    new actions.IotRepublishMqttAction('test-topic', { qos: actions.MqttQualityOfService.AT_LEAST_ONCE }),
+  );
+
+  // THEN
+  Template.fromStack(stack).hasResourceProperties('AWS::IoT::TopicRule', {
+    TopicRulePayload: {
+      Actions: [
+        Match.objectLike({ Republish: { Qos: 1 } }),
+      ],
+    },
+  });
+});
+
+test('can set role', () => {
+  // WHEN
+  const role = iam.Role.fromRoleArn(stack, 'MyRole', 'arn:aws:iam::123456789012:role/ForTest');
+  topicRule.addAction(
+    new actions.IotRepublishMqttAction('test-topic', { role }),
+  );
+
+  // THEN
+  Template.fromStack(stack).hasResourceProperties('AWS::IoT::TopicRule', {
+    TopicRulePayload: {
+      Actions: [
+        Match.objectLike({ Republish: { RoleArn: 'arn:aws:iam::123456789012:role/ForTest' } }),
+      ],
+    },
+  });
+
+  Template.fromStack(stack).hasResourceProperties('AWS::IAM::Policy', {
+    PolicyName: 'MyRolePolicy64AB00A5',
+    Roles: ['ForTest'],
+  });
+});