feat(ec2): add support for vpn connections (#1899)

Add support for Site-to-Site VPN connections to VPC networks.

When VPN connections are specified, a VPN gateway is automatically
created and attached to the VPC. By default, routes are propagated on the
route tables associated with the private subnets. Propagation to routes
tables associated with public and/or isolated subnets is supported.

Update VPC context provider to also import vpnGatewayId.

References aws/jsii#231

packages/@aws-cdk/aws-ec2/README.md

@@ -303,3 +303,41 @@ selectable by instantiating one of these classes:
 > section of your `cdk.json`.
 >
 > We will add command-line options to make this step easier in the future.
+
+### VPN connections to a VPC
+
+Create your VPC with VPN connections by specifying the `vpnConnections` props (keys are construct `id`s):
+
+```ts
+const vpc = new ec2.VpcNetwork(stack, 'MyVpc', {
+  vpnConnections: {
+    dynamic: { // Dynamic routing (BGP)
+      ip: '1.2.3.4'
+    },
+    static: { // Static routing
+      ip: '4.5.6.7',
+      staticRoutes: [
+        '192.168.10.0/24',
+        '192.168.20.0/24'
+      ]
+    }
+  }
+});
+```
+
+To create a VPC that can accept VPN connections, set `vpnGateway` to `true`:
+
+```ts
+const vpc = new ec2.VpcNetwork(stack, 'MyVpc', {
+  vpnGateway: true
+});
+```
+
+VPN connections can then be added:
+```ts
+vpc.addVpnConnection('Dynamic', {
+  ip: '1.2.3.4'
+});
+```
+
+Routes will be propagated on the route tables associated with the private subnets.

packages/@aws-cdk/aws-ec2/lib/index.ts

@@ -6,6 +6,7 @@ export * from './security-group-rule';
 export * from './vpc';
 export * from './vpc-ref';
 export * from './vpc-network-provider';
+export * from './vpn';
 
 // AWS::EC2 CloudFormation Resources:
 export * from './ec2.generated';

packages/@aws-cdk/aws-ec2/lib/vpc-ref.ts

@@ -1,5 +1,6 @@
 import { Construct, IConstruct, IDependable } from "@aws-cdk/cdk";
 import { subnetName } from './util';
+import { VpnConnection, VpnConnectionOptions } from './vpn';
 
 export interface IVpcSubnet extends IConstruct {
   /**
@@ -54,6 +55,11 @@ export interface IVpcNetwork extends IConstruct {
    */
   readonly vpcRegion: string;
 
+  /**
+   * Identifier for the VPN gateway
+   */
+  readonly vpnGatewayId?: string;
+
   /**
    * Return the subnets appropriate for the placement strategy
    */
@@ -68,6 +74,11 @@ export interface IVpcNetwork extends IConstruct {
    */
   isPublicSubnet(subnet: IVpcSubnet): boolean;
 
+  /**
+   * Adds a new VPN connection to this VPC
+   */
+  addVpnConnection(id: string, options: VpnConnectionOptions): VpnConnection;
+
   /**
    * Exports this VPC so it can be consumed by another stack.
    */
@@ -173,6 +184,11 @@ export abstract class VpcNetworkBase extends Construct implements IVpcNetwork {
    */
   public abstract readonly availabilityZones: string[];
 
+  /**
+   * Identifier for the VPN gateway
+   */
+  public abstract readonly vpnGatewayId?: string;
+
   /**
    * Dependencies for internet connectivity
    */
@@ -211,6 +227,16 @@ export abstract class VpcNetworkBase extends Construct implements IVpcNetwork {
     }[placement.subnetsToUse];
   }
 
+  /**
+   * Adds a new VPN connection to this VPC
+   */
+  public addVpnConnection(id: string, options: VpnConnectionOptions): VpnConnection {
+    return new VpnConnection(this, id, {
+      vpc: this,
+      ...options
+    });
+  }
+
   /**
    * Export this VPC from the stack
    */
@@ -291,6 +317,11 @@ export interface VpcNetworkImportProps {
    * Must be undefined or have a name for every isolated subnet group.
    */
   isolatedSubnetNames?: string[];
+
+  /**
+   * VPN gateway's identifier
+   */
+  vpnGatewayId?: string;
 }
 
 export interface VpcSubnetImportProps {

packages/@aws-cdk/aws-ec2/lib/vpc.ts

@@ -1,11 +1,12 @@
 import cdk = require('@aws-cdk/cdk');
 import { ConcreteDependable, IDependable } from '@aws-cdk/cdk';
-import { CfnEIP, CfnInternetGateway, CfnNatGateway, CfnRoute } from './ec2.generated';
+import { CfnEIP, CfnInternetGateway, CfnNatGateway, CfnRoute, CfnVPNGateway, CfnVPNGatewayRoutePropagation } from './ec2.generated';
 import { CfnRouteTable, CfnSubnet, CfnSubnetRouteTableAssociation, CfnVPC, CfnVPCGatewayAttachment } from './ec2.generated';
 import { NetworkBuilder } from './network-util';
 import { DEFAULT_SUBNET_NAME, ExportSubnetGroup, ImportSubnetGroup, subnetId  } from './util';
 import { VpcNetworkProvider, VpcNetworkProviderProps } from './vpc-network-provider';
 import { IVpcNetwork, IVpcSubnet, SubnetType, VpcNetworkBase, VpcNetworkImportProps, VpcPlacementStrategy, VpcSubnetImportProps } from './vpc-ref';
+import { VpnConnectionOptions, VpnConnectionType } from './vpn';
 
 /**
  * Name tag constant
@@ -115,6 +116,34 @@ export interface VpcNetworkProps {
    * private subnet per AZ
    */
   subnetConfiguration?: SubnetConfiguration[];
+
+  /**
+   * Indicates whether a VPN gateway should be created and attached to this VPC.
+   *
+   * @default true when vpnGatewayAsn or vpnConnections is specified.
+   */
+  vpnGateway?: boolean;
+
+  /**
+   * The private Autonomous System Number (ASN) for the VPN gateway.
+   *
+   * @default Amazon default ASN
+   */
+  vpnGatewayAsn?: number;
+
+  /**
+   * VPN connections to this VPC.
+   *
+   * @default no connections
+   */
+  vpnConnections?: { [id: string]: VpnConnectionOptions }
+
+  /**
+   * Where to propagate VPN routes.
+   *
+   * @default on the route tables associated with private subnets
+   */
+  vpnRoutePropagation?: SubnetType[]
 }
 
 /**
@@ -250,6 +279,11 @@ export class VpcNetwork extends VpcNetworkBase {
    */
   public readonly availabilityZones: string[];
 
+  /**
+   * Identifier for the VPN gateway
+   */
+  public readonly vpnGatewayId?: string;
+
   /**
    * The VPC resource
    */
@@ -343,6 +377,51 @@ export class VpcNetwork extends VpcNetworkBase {
         privateSubnet.addDefaultNatRouteEntry(ngwId);
       });
     }
+
+    if ((props.vpnConnections || props.vpnGatewayAsn) && props.vpnGateway === false) {
+      throw new Error('Cannot specify `vpnConnections` or `vpnGatewayAsn` when `vpnGateway` is set to false.');
+    }
+
+    if (props.vpnGateway || props.vpnConnections || props.vpnGatewayAsn) {
+      const vpnGateway = new CfnVPNGateway(this, 'VpnGateway', {
+        amazonSideAsn: props.vpnGatewayAsn,
+        type: VpnConnectionType.IPsec1
+      });
+
+      const attachment = new CfnVPCGatewayAttachment(this, 'VPCVPNGW', {
+        vpcId: this.vpcId,
+        vpnGatewayId: vpnGateway.vpnGatewayName
+      });
+
+      this.vpnGatewayId = vpnGateway.vpnGatewayName;
+
+      // Propagate routes on route tables associated with the right subnets
+      const vpnRoutePropagation = props.vpnRoutePropagation || [SubnetType.Private];
+      let subnets: IVpcSubnet[] = [];
+      if (vpnRoutePropagation.includes(SubnetType.Public)) {
+        subnets = [...subnets, ...this.publicSubnets];
+      }
+      if (vpnRoutePropagation.includes(SubnetType.Private)) {
+        subnets = [...subnets, ...this.privateSubnets];
+      }
+      if (vpnRoutePropagation.includes(SubnetType.Isolated)) {
+        subnets = [...subnets, ...this.isolatedSubnets];
+      }
+      const routePropagation = new CfnVPNGatewayRoutePropagation(this, 'RoutePropagation', {
+        routeTableIds: (subnets as VpcSubnet[]).map(subnet => subnet.routeTableId),
+        vpnGatewayId: this.vpnGatewayId
+      });
+
+      // The AWS::EC2::VPNGatewayRoutePropagation resource cannot use the VPN gateway
+      // until it has successfully attached to the VPC.
+      // See https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ec2-vpn-gatewayrouteprop.html
+      routePropagation.node.addDependency(attachment);
+
+      const vpnConnections = props.vpnConnections || {};
+      for (const [connectionId, connection] of Object.entries(vpnConnections)) {
+        this.addVpnConnection(connectionId, connection);
+      }
+    }
   }
 
   /**
@@ -355,6 +434,7 @@ export class VpcNetwork extends VpcNetworkBase {
 
     return {
       vpcId: new cdk.Output(this, 'VpcId', { value: this.vpcId }).makeImportValue().toString(),
+      vpnGatewayId: new cdk.Output(this, 'VpnGatewayId', { value: this.vpnGatewayId }).makeImportValue().toString(),
       availabilityZones: this.availabilityZones,
       publicSubnetIds: pub.ids,
       publicSubnetNames: pub.names,
@@ -523,7 +603,7 @@ export class VpcSubnet extends cdk.Construct implements IVpcSubnet {
   /**
    * The routeTableId attached to this subnet.
    */
-  private readonly routeTableId: string;
+  public readonly routeTableId: string;
 
   private readonly internetDependencies = new ConcreteDependable();
 
@@ -653,12 +733,14 @@ class ImportedVpcNetwork extends VpcNetworkBase {
   public readonly privateSubnets: IVpcSubnet[];
   public readonly isolatedSubnets: IVpcSubnet[];
   public readonly availabilityZones: string[];
+  public readonly vpnGatewayId?: string;
 
   constructor(scope: cdk.Construct, id: string, private readonly props: VpcNetworkImportProps) {
     super(scope, id);
 
     this.vpcId = props.vpcId;
     this.availabilityZones = props.availabilityZones;
+    this.vpnGatewayId = props.vpnGatewayId;
 
     // tslint:disable:max-line-length
     const pub = new ImportSubnetGroup(props.publicSubnetIds, props.publicSubnetNames, SubnetType.Public, this.availabilityZones, 'publicSubnetIds', 'publicSubnetNames');