feat(rds): add support for database instances (#2187)

Specific classes are exposed for a source database instance (`DatabaseInstance`), an instance created from a snapshot (`DatabaseInstanceFromSnapshot`) and a read replica instance (`DatabaseInstanceReadReplica`).

Add construct for option groups and refactor parameter groups.

Add basic support for instance event rules.

Integration with Secrets Manager and secret rotation.

Closes #2075 
Closes #1693

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

@@ -1,27 +1,8 @@
 ## AWS RDS Construct Library
 
-The `aws-cdk-rds` package contains Constructs for setting up RDS instances.
-
-> Note: the functionality this package is currently limited, as the CDK team is
-> focusing on other use cases first. If your use case is not listed below, you
-> will have to use achieve it using CloudFormation resources.
->
-> If you would like to help improve the state of this library, Pull Requests are
-> welcome.
-
-Supported:
-
-* Clustered databases
-
-Not supported:
-
-* Instance databases
-* Setting up from a snapshot
-
-
 ### Starting a Clustered Database
 
-To set up a clustered database (like Aurora), create an instance of `DatabaseCluster`. You must
+To set up a clustered database (like Aurora), define a `DatabaseCluster`. You must
 always launch a database in a VPC. Use the `vpcSubnets` attribute to control whether
 your instances will be launched privately or publicly:
 
@@ -45,33 +26,84 @@ By default, the master password will be generated and stored in AWS Secrets Mana
 Your cluster will be empty by default. To add a default database upon construction, specify the
 `defaultDatabaseName` attribute.
 
+### Starting an Instance Database
+To set up a instance database, define a `DatabaseInstance`. You must
+always launch a database in a VPC. Use the `vpcSubnets` attribute to control whether
+your instances will be launched privately or publicly:
+
+```ts
+const instance = new DatabaseInstance(stack, 'Instance', {
+    engine: rds.DatabaseInstanceEngine.OracleSE1,
+    instanceClass: new ec2.InstanceTypePair(ec2.InstanceClass.Burstable2, ec2.InstanceSize.Small),
+    masterUsername: 'syscdk',
+    vpc
+});
+```
+By default, the master password will be generated and stored in AWS Secrets Manager.
+
+Use `DatabaseInstanceFromSnapshot` and `DatabaseInstanceReadReplica` to create an instance from snapshot or
+a source database respectively:
+
+```ts
+new DatabaseInstanceFromSnapshot(stack, 'Instance', {
+    snapshotIdentifier: 'my-snapshot',
+    engine: rds.DatabaseInstanceEngine.Postgres,
+    instanceClass: new ec2.InstanceTypePair(ec2.InstanceClass.Burstable2, ec2.InstanceSize.Large),
+    vpc
+});
+
+new DatabaseInstanceReadReplica(stack, 'ReadReplica', {
+    sourceDatabaseInstance: sourceInstance,
+    engine: rds.DatabaseInstanceEngine.Postgres,
+    instanceClass: new ec2.InstanceTypePair(ec2.InstanceClass.Burstable2, ec2.InstanceSize.Large),
+    vpc
+});
+```
+Creating a "production" Oracle database instance with option and parameter groups:
+
+[example of setting up a production oracle instance](test/integ.instance.lit.ts)
+
+
+### Instance events
+To define Amazon CloudWatch event rules for database instances, use the `onEvent`
+method:
+
+```ts
+const rule = instance.onEvent('InstanceEvent', { target: new targets.LambdaFunction(fn) });
+```
+
 ### Connecting
 
-To control who can access the cluster, use the `.connections` attribute. RDS database have
+To control who can access the cluster or instance, use the `.connections` attribute. RDS databases have
 a default port, so you don't need to specify the port:
 
 ```ts
 cluster.connections.allowFromAnyIpv4('Open to the world');
 ```
 
-The endpoints to access your database will be available as the `.clusterEndpoint` and `.readerEndpoint`
+The endpoints to access your database cluster will be available as the `.clusterEndpoint` and `.readerEndpoint`
 attributes:
 
 ```ts
 const writeAddress = cluster.clusterEndpoint.socketAddress;   // "HOSTNAME:PORT"
 ```
 
+For an instance database:
+```ts
+const address = instance.instanceEndpoint.socketAddress;   // "HOSTNAME:PORT"
+```
+
 ### Rotating master password
 When the master password is generated and stored in AWS Secrets Manager, it can be rotated automatically:
 
-[example of setting up master password rotation](test/integ.cluster-rotation.lit.ts)
+[example of setting up master password rotation for a cluster](test/integ.cluster-rotation.lit.ts)
 
 Rotation of the master password is also supported for an existing cluster:
 ```ts
-new RotationSingleUser(stack, 'Rotation', {
+new SecretRotation(stack, 'Rotation', {
     secret: importedSecret,
-    engine: DatabaseEngine.Oracle,
-    target: importedCluster,
+    application: SecretRotationApplication.OracleRotationSingleUser
+    target: importedCluster, // or importedInstance
     vpc: importedVpc,
 })
 ```
@@ -87,3 +119,13 @@ The `importedSecret` must be a JSON string with the following format:
   "port": "<optional: if not specified, default port will be used>"
 }
 ```
+
+### Metrics
+Database instances expose metrics (`cloudwatch.Metric`):
+```ts
+// The number of database connections in use (average over 5 minutes)
+const dbConnections = instance.metricDatabaseConnections();
+
+// The average amount of time taken per disk I/O operation (average over 1 minute)
+const readLatency = instance.metric('ReadLatency', { statistic: 'Average', periodSec: 60 });
+```

packages/@aws-cdk/aws-rds/lib/cluster-ref.ts

@@ -1,12 +1,12 @@
 import ec2 = require('@aws-cdk/aws-ec2');
 import secretsmanager = require('@aws-cdk/aws-secretsmanager');
-import cdk = require('@aws-cdk/cdk');
-import { Token } from '@aws-cdk/cdk';
+import { IResource } from '@aws-cdk/cdk';
+import { Endpoint } from './endpoint';
 
 /**
  * Create a clustered database with a given number of instances.
  */
-export interface IDatabaseCluster extends cdk.IResource, ec2.IConnectable, secretsmanager.ISecretAttachmentTarget {
+export interface IDatabaseCluster extends IResource, ec2.IConnectable, secretsmanager.ISecretAttachmentTarget {
   /**
    * Identifier of the cluster
    */
@@ -80,33 +80,3 @@ export interface DatabaseClusterAttributes {
    */
   readonly instanceEndpointAddresses: string[];
 }
-
-/**
- * Connection endpoint of a database cluster or instance
- *
- * Consists of a combination of hostname and port.
- */
-export class Endpoint {
-  /**
-   * The hostname of the endpoint
-   */
-  public readonly hostname: string;
-
-  /**
-   * The port of the endpoint
-   */
-  public readonly port: number;
-
-  /**
-   * The combination of "HOSTNAME:PORT" for this endpoint
-   */
-  public readonly socketAddress: string;
-
-  constructor(address: string, port: number) {
-    this.hostname = address;
-    this.port = port;
-
-    const portDesc = Token.isToken(port) ? '{IndirectPort}' : port;
-    this.socketAddress = `${address}:${portDesc}`;
-  }
-}

packages/@aws-cdk/aws-rds/lib/cluster.ts

@@ -2,12 +2,13 @@ import ec2 = require('@aws-cdk/aws-ec2');
 import kms = require('@aws-cdk/aws-kms');
 import secretsmanager = require('@aws-cdk/aws-secretsmanager');
 import { Construct, DeletionPolicy, Resource, Token } from '@aws-cdk/cdk';
-import { IClusterParameterGroup } from './cluster-parameter-group';
-import { DatabaseClusterAttributes, Endpoint, IDatabaseCluster } from './cluster-ref';
+import { DatabaseClusterAttributes, IDatabaseCluster } from './cluster-ref';
 import { DatabaseSecret } from './database-secret';
+import { Endpoint } from './endpoint';
+import { IParameterGroup } from './parameter-group';
 import { BackupProps, DatabaseClusterEngine, InstanceProps, Login } from './props';
 import { CfnDBCluster, CfnDBInstance, CfnDBSubnetGroup } from './rds.generated';
-import { DatabaseEngine, RotationSingleUser, RotationSingleUserOptions } from './rotation-single-user';
+import { SecretRotation, SecretRotationApplication, SecretRotationOptions } from './secret-rotation';
 
 /**
  * Properties for a new database cluster
@@ -111,7 +112,7 @@ export interface DatabaseClusterProps {
    *
    * @default - No parameter group.
    */
-  readonly parameterGroup?: IClusterParameterGroup;
+  readonly parameterGroup?: IParameterGroup;
 
   /**
    * The CloudFormation policy to apply when the cluster and its instances
@@ -241,7 +242,7 @@ export class DatabaseCluster extends DatabaseClusterBase {
   /**
    * The database engine of this cluster
    */
-  public readonly engine: DatabaseClusterEngine;
+  private readonly secretRotationApplication: SecretRotationApplication;
 
   /**
    * The VPC where the DB subnet group is created.
@@ -286,11 +287,11 @@ export class DatabaseCluster extends DatabaseClusterBase {
       });
     }
 
-    this.engine = props.engine;
+    this.secretRotationApplication = props.engine.secretRotationApplication;
 
     const cluster = new CfnDBCluster(this, 'Resource', {
       // Basic
-      engine: this.engine,
+      engine: props.engine.name,
       dbClusterIdentifier: props.clusterIdentifier,
       dbSubnetGroupName: subnetGroup.ref,
       vpcSecurityGroupIds: [this.securityGroupId],
@@ -347,14 +348,15 @@ export class DatabaseCluster extends DatabaseClusterBase {
 
       const instance = new CfnDBInstance(this, `Instance${instanceIndex}`, {
         // Link to cluster
-        engine: props.engine,
+        engine: props.engine.name,
         dbClusterIdentifier: cluster.ref,
         dbInstanceIdentifier: instanceIdentifier,
         // Instance properties
         dbInstanceClass: databaseInstanceType(props.instanceProps.instanceType),
         publiclyAccessible,
         // This is already set on the Cluster. Unclear to me whether it should be repeated or not. Better yes.
         dbSubnetGroupName: subnetGroup.ref,
+        dbParameterGroupName: props.instanceProps.parameterGroup && props.instanceProps.parameterGroup.parameterGroupName,
       });
 
       instance.options.deletionPolicy = deleteReplacePolicy;
@@ -375,13 +377,13 @@ export class DatabaseCluster extends DatabaseClusterBase {
   /**
    * Adds the single user rotation of the master password to this cluster.
    */
-  public addRotationSingleUser(id: string, options: RotationSingleUserOptions = {}): RotationSingleUser {
+  public addRotationSingleUser(id: string, options: SecretRotationOptions = {}): SecretRotation {
     if (!this.secret) {
       throw new Error('Cannot add single user rotation for a cluster without secret.');
     }
-    return new RotationSingleUser(this, id, {
+    return new SecretRotation(this, id, {
       secret: this.secret,
-      engine: toDatabaseEngine(this.engine),
+      application: this.secretRotationApplication,
       vpc: this.vpc,
       vpcSubnets: this.vpcSubnets,
       target: this,
@@ -396,20 +398,3 @@ export class DatabaseCluster extends DatabaseClusterBase {
 function databaseInstanceType(instanceType: ec2.InstanceType) {
   return 'db.' + instanceType.toString();
 }
-
-/**
- * Transforms a DatbaseClusterEngine to a DatabaseEngine.
- *
- * @param engine the engine to transform
- */
-function toDatabaseEngine(engine: DatabaseClusterEngine): DatabaseEngine {
-  switch (engine) {
-    case DatabaseClusterEngine.Aurora:
-    case DatabaseClusterEngine.AuroraMysql:
-      return DatabaseEngine.Mysql;
-    case DatabaseClusterEngine.AuroraPostgresql:
-      return DatabaseEngine.Postgres;
-    default:
-      throw new Error('Unknown engine');
-  }
-}