Using aws ec2transitgateway with dms

Question

Pulumi · Accepted Answer

When integrating AWS EC2 Transit Gateway with AWS Database Migration Service (DMS), the goal is typically to allow the DMS to access resources that are in different AWS VPCs connected through the Transit Gateway. AWS DMS is a service that enables you to migrate relational databases, data warehouses, NoSQL databases, and other types of data stores.

Below is a TypeScript program using Pulumi to set up the necessary AWS resources. The program will:

1. Create an EC2 Transit Gateway, which allows you to connect VPCs and on-premises networks through a central hub.
2. Set up a DMS Replication Instance, which performs the actual data migration.
3. Ensure that the Replication Instance resides within a VPC that is attached to the Transit Gateway.

Here is a detailed explanation of the code structure:

- Import statements: These bring in the required Pulumi AWS package modules needed for defining AWS resources.
- Transit Gateway Creation: The Transit Gateway is created with default routing options. Additional configurations can be modified as needed.
- Subnet Group for DMS: Before creating a DMS instance, a subnet group is defined. The subnet group tells DMS in which subnets the replication instance will be created.
- DMS Replication Instance: This resource manages a DMS replication instance, specifying the VPC security group and subnet group associated with it. The instance will be within the VPC attached to the Transit Gateway.

Let's look at the actual program:

```typescript
import * as pulumi from "@pulumi/pulumi";
import * as aws from "@pulumi/aws";

// Create a Transit Gateway.
const transitGateway = new aws.ec2transitgateway.TransitGateway("myTransitGateway", {
    description: "Transit Gateway for DMS connectivity between VPCs",
    // Other options can be set according to the needs.
});

// Create a Replication Subnet Group for DMS.
// We assume here that you have a list of subnet IDs in which you want the replication instances to reside.
const dmsSubnetGroup = new aws.dms.ReplicationSubnetGroup("myDmsSubnetGroup", {
    // Replace these subnet IDs with the ones from your VPCs that are connected through the Transit Gateway.
    subnetIds: ["subnet-12345678", "subnet-87654321"],
    replicationSubnetGroupDescription: "DMS Replication Subnet Group",
    // Optional: set tags if needed.
    // tags: { ... },
});

// Create a DMS Replication Instance.
const dmsInstance = new aws.dms.ReplicationInstance("myDmsInstance", {
    replicationInstanceClass: "dms.t2.micro", // Choose the DB instance class that suits your needs.
    replicationSubnetGroup: dmsSubnetGroup.replicationSubnetGroupArn,
    vpcSecurityGroupIds: [transitGateway.id], // Associating it with the Transit Gateway's security group.
    
    // These would be your DMS settings, such as replication engine version and other configurations.
    // replicationEngineVersion: "...",
    
    // Tags for identification and management purposes.
    tags: {
        Name: "My DMS Replication Instance",
    },
});

// Export the IDs of the created resources so that they can be accessed and referenced outside of Pulumi.
export const transitGatewayId = transitGateway.id;
export const dmsSubnetGroupId = dmsSubnetGroup.id;
export const dmsInstanceId = dmsInstance.replicationInstanceId;
```

This program sets up the EC2 Transit Gateway and then configures a DMS Replication Instance in a subnet that is connected via the Transit Gateway. While the security groups are not specifically set in this example, you would normally configure your VPC security groups to allow DMS to access the databases it needs to replicate.

Remember to replace the placeholder values (like the subnet IDs) with actual values from your AWS environment. After deploying these resources using Pulumi, your Transit Gateway will facilitate communication between DMS and the resources across your VPCs.

To deploy this infrastructure, run the following commands in your terminal:

1. `pulumi up` - This command will compile the TypeScript program, check for errors, and display a preview of the resources that will be created.
2. Review the preview and if everything is correct, confirm the deployment by selecting 'yes'.

The deployment may take a few minutes, and once completed, Pulumi will provide outputs such as the Transit Gateway ID and the DMS Replication Instance ID. These outputs can be used to reference the resources in other parts of your infrastructure or in your applications.