Using azure subnet with route-table-component

Question

Pulumi · Accepted Answer

In Azure, a subnet is a range of IP addresses in the virtual network where you can launch Azure resources. Subnets allow you to segment the virtual network into one or more sub-networks, providing better network organization, improved routing, and enhanced security. A route table, on the other hand, contains a set of rules, called routes, that determine where network traffic from your subnet or virtual network gateway is directed.

In Pulumi, to associate a subnet with a route table, you would first create a Virtual Network and Route Table separately and then link the subnet to the route table by referring to the route table's ID.

Below is a Pulumi program written in TypeScript that:

1. Creates a Virtual Network.
2. Creates a Subnet within the Virtual Network.
3. Creates a Route Table.
4. Associates the Route Table with the Subnet.

```typescript
import * as pulumi from "@pulumi/pulumi";
import * as azure from "@pulumi/azure-native";

// Create an Azure Resource Group
const resourceGroup = new azure.resources.ResourceGroup("myResourceGroup");

// Create an Azure Virtual Network
const virtualNetwork = new azure.network.VirtualNetwork("myVnet", {
    resourceGroupName: resourceGroup.name,
    addressSpace: {
        addressPrefixes: ["10.0.0.0/16"],
    },
});

// Create a subnet. Note that we do not associate the route table here.
const subnet = new azure.network.Subnet("mySubnet", {
    resourceGroupName: resourceGroup.name,
    virtualNetworkName: virtualNetwork.name,
    addressPrefix: "10.0.1.0/24",
    // The subnet properties go here. We will associate the route table after its creation.
});

// Create a route table with a route. We'll add a route that directs traffic to the Internet.
const routeTable = new azure.network.RouteTable("myRouteTable", {
    resourceGroupName: resourceGroup.name,
    disableBgpRoutePropagation: false,
    routes: [{
        name: "myRoute",
        addressPrefix: "0.0.0.0/0", // Represents all IPv4 addresses.
        nextHopType: azure.network.RouteNextHopType.Internet,
    }],
});

// Associate the route table with the subnet
const subnetRouteTableAssociation = new azure.network.SubnetRouteTableAssociation("mySubnetRouteTableAssociation", {
    subnetId: subnet.id,
    routeTableId: routeTable.id,
});

export const subnetId = subnet.id;
export const routeTableId = routeTable.id;
```

Here's a breakdown of this program:

- We're using the `@pulumi/azure-native` package to provision resources in Azure using Pulumi. This package provides classes that correspond to the actual Azure resources.
  
- The `ResourceGroup` class creates a resource group in Azure, a logical container into which Azure resources like networking, storage accounts, VMs, and others are deployed and managed.

- The `VirtualNetwork` class creates a VNet in Azure. Here we define the address space for the VNet with a single address prefix.

- Then we use the `Subnet` class to define a subnet within our VNet. At this point, we haven't tied it to a route table. The subnet's address prefix must be within the VNet's address range.

- The `RouteTable` class is used to create a route table. We add a route that directs all Internet-bound traffic (0.0.0.0/0) through a next hop defined by `RouteNextHopType.Internet`.

- The `SubnetRouteTableAssociation` class is then used to associate the previously created `subnet` with the `routeTable`. The association is done by referencing the IDs of these resources, connecting them within Azure.

- Finally, we export the IDs of the subnet and route table. These IDs can be useful for referencing these resources in other parts of your Pulumi program or in separate stacks.

Make sure to replace `myResourceGroup`, `myVnet`, `mySubnet`, `myRouteTable`, and `myRoute` with your desired resource names. This program can be run in a Pulumi environment with your Azure account configured, and it will provision the resources described above on your Azure subscription.