Private Subnets for High-Performance GPU Clusters on EC2

Question

Pulumi · Accepted Answer

To create private subnets for high-performance GPU clusters on Amazon EC2, we'll need to set up a VPC (Virtual Private Cloud), define our subnets, and configure routing so that our GPU instances can communicate with each other and other necessary services, while not being directly accessible from the public internet.

Here's what the process generally entails:

1. **Create a VPC**: A VPC is a virtual network dedicated to your AWS account. It is logically isolated from other virtual networks in the AWS Cloud.
2. **Create Subnets**: Each subnet is associated with a specific Availability Zone and cannot span zones. By creating a private subnet, we restrict its access from the public internet.
3. **Routing and Internet Gateway**: While our subnets are private, our instances will likely need to reach the internet for updates and patches. We'll create a NAT Gateway for outbound traffic.

The following Pulumi program in Python will guide you through each step, setting up a VPC with a pair of private subnets suitable for hosting EC2 instances configured with GPUs.

Make sure to have the Pulumi AWS package installed in your Python environment, and AWS credentials configured with the necessary permissions.

```python
import pulumi
import pulumi_aws as aws

# Configure the AWS region you wish to deploy resources into
aws.config.region = "us-west-2"

# Create a new VPC
vpc = aws.ec2.Vpc("gpu-vpc",
    cidr_block="10.0.0.0/16",
    enable_dns_support=True,
    enable_dns_hostnames=True,
    tags={
        "Name": "gpu-vpc",
    })

# Create an Internet Gateway for our VPC (for the NAT Gateway)
internet_gateway = aws.ec2.InternetGateway("gpu-igw",
    vpc_id=vpc.id,
    tags={
        "Name": "gpu-igw",
    })

# Create a route table for the internet gateway
public_route_table = aws.ec2.RouteTable("gpu-public-rt",
    vpc_id=vpc.id,
    routes=[aws.ec2.RouteTableRouteArgs(
        cidr_block="0.0.0.0/0",
        gateway_id=internet_gateway.id,
    )],
    tags={
        "Name": "gpu-public-rt",
    })

# Create subnets for the GPU instances
# We're creating two private subnets in different Availability Zones
# for high availability.
subnet1 = aws.ec2.Subnet("gpu-subnet-1",
    vpc_id=vpc.id,
    cidr_block="10.0.1.0/24",
    availability_zone="us-west-2a",
    map_public_ip_on_launch=False,
    tags={
        "Name": "gpu-subnet-1",
    })

subnet2 = aws.ec2.Subnet("gpu-subnet-2",
    vpc_id=vpc.id,
    cidr_block="10.0.2.0/24",
    availability_zone="us-west-2b",
    map_public_ip_on_launch=False,
    tags={
        "Name": "gpu-subnet-2",
    })

# Create a NAT Gateway in the public subnet to allow instances in the
# private subnet to access the Internet for updates
elastic_ip = aws.ec2.Eip("gpu-eip", vpc=True)
nat_gateway = aws.ec2.NatGateway("gpu-nat-gateway",
    subnet_id=subnet1.id,  # We place the NAT Gateway in the first subnet
    allocation_id=elastic_ip.id,
    tags={
        "Name": "gpu-nat-gateway",
    })

# Create a private route table for our subnets
private_route_table = aws.ec2.RouteTable("gpu-private-rt",
    vpc_id=vpc.id,
    routes=[aws.ec2.RouteTableRouteArgs(
        cidr_block="0.0.0.0/0",
        nat_gateway_id=nat_gateway.id,  # Associate with the NAT Gateway
    )],
    tags={
        "Name": "gpu-private-rt",
    })

# Associate our private subnets with the private route table
aws.ec2.RouteTableAssociation("gpu-rt-assoc1",
    route_table_id=private_route_table.id,
    subnet_id=subnet1.id)

aws.ec2.RouteTableAssociation("gpu-rt-assoc2",
    route_table_id=private_route_table.id,
    subnet_id=subnet2.id)

# Output the IDs of the VPC and subnets
pulumi.export("vpc_id", vpc.id)
pulumi.export("subnet1_id", subnet1.id)
pulumi.export("subnet2_id", subnet2.id)
```

This program creates:
- A new VPC for our resources.
- An internet gateway and a public route table for outbound traffic.
- Two private subnets across two different Availability Zones for redundancy and high availability.
- A NAT Gateway with an Elastic IP to allow outbound internet access.
- Route table associations to route traffic accordingly.

Once this infrastructure is in place, you may provision EC2 instances with GPU capabilities within these private subnets. They will be able to access the internet via the NAT Gateway, but won't be accessible from the internet directly, ensuring a level of privacy and security for your compute resources.