Setting up a Hybrid Connection between Azure App Service and a private datacenter

Question

Pulumi · Accepted Answer

To set up a Hybrid Connection between an Azure App Service and a private datacenter, you will need to utilize several Azure resources. The key components of this setup include the Azure App Service, which will host your web application, and the Azure Relay Hybrid Connections, which will facilitate the secure communication between the Azure App Service and your on-premises datacenter. The communication is established without the need to open a firewall connection or require VPN or other networking changes on your premises.

Below is a walkthrough and a corresponding Pulumi TypeScript program that sets up a basic instance of an Azure App Service and configures a Hybrid Connection to a private datacenter.

### Walkthrough

1. **Azure App Service Plan**: The backbone for hosting the Azure App Service, providing the necessary compute resources.

2. **Azure App Service**: Contains the web application which you will be connecting to the private datacenter. The service needs to be associated with an App Service Plan for hosting.

3. **Azure Relay Namespace**: A container for the Hybrid Connection, allowing a secure way to access resources within your corporate network.

4. **Azure Relay Hybrid Connection**: Specifies the actual connection between the Azure services and the on-premises services. It requires configuration details such as the hostname and port of the on-premises service that you want to connect to.

5. **Azure App Service Hybrid Connection**: This is the resource that links the App Service with the Hybrid Connection in the Azure Relay.

Make sure that you install the appropriate Pulumi package for the Azure provider and log in to the Azure CLI before running a Pulumi program on your local machine.

Here's an example Pulumi TypeScript program that establishes such a connection:

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

// Create a resource group to contain all the resources
const resourceGroup = new azure.resources.ResourceGroup("my-resource-group");

// Create an App Service Plan
const appServicePlan = new azure.web.AppServicePlan("my-app-service-plan", {
    // Ensure you have the correct location and resource group name
    location: resourceGroup.location,
    resourceGroupName: resourceGroup.name,
    sku: {
        name: "B1", // Choose an appropriate pricing tier
    },
});

// Create an App Service
const appService = new azure.web.WebApp("my-app-service", {
    // Make sure to provide the right names for the plan and resource group
    resourceGroupName: resourceGroup.name,
    serverFarmId: appServicePlan.id,
    siteConfig: {
        // ... additional site configurations
    },
});

// Define a Relay Namespace for the Hybrid Connection
const relayNamespace = new azure.relay.Namespace("my-relay-namespace", {
    location: resourceGroup.location,
    resourceGroupName: resourceGroup.name,
    sku: {
        name: "Standard", // Choose between 'Standard' and 'Premium'
    },
});

// Define the Hybrid Connection
const hybridConnection = new azure.relay.HybridConnection("my-hybrid-connection", {
    resourceGroupName: resourceGroup.name,
    relayNamespaceName: relayNamespace.name,
    userMetadata: "App Service to On-Premises Connection",
    // Set 'requiresClientAuthorization' to false if you want to bypass token-based authorization
    requiresClientAuthorization: true,
});

// Link the App Service to the Hybrid Connection
const appServiceHybridConnection = new azure.web.WebAppHybridConnection("my-appservice-hybrid-connection", {
    resourceGroupName: resourceGroup.name,
    name: appService.name,
    namespaceName: relayNamespace.name,
    relayName: hybridConnection.name,
    // Hybrid connection properties such as hostname and port go here
    hostname: "my-onprem-service.local", // Replace with your on-premises service hostname
    port: 8080, // Replace with your on-premises service port
});

// Optionally, export the endpoints or other properties that are important
export const appServiceEndpoint = appService.defaultHostName;
export const hybridConnectionId = hybridConnection.id;
```

In this code, we start by defining an `azure.resources.ResourceGroup`, which logically groups all the resources we're going to create.

Next, we declare a new `azure.web.AppServicePlan` that specifies the pricing tier and location for hosting our App Service.

We create a `azure.web.WebApp` to host our application, linking it to the app service plan created earlier.

Then we define a `azure.relay.Namespace` to hold our relay resources.

Following that, we create a `azure.relay.HybridConnection` where we define the resource attributes specific to the communication between Azure and your private datacenter.

Finally, we associate our `azure.web.WebApp` with the `azure.relay.HybridConnection` using an instance of `azure.web.WebAppHybridConnection`. Here we specify the hostname and port of our on-premise resource that the Azure App Service needs to communicate with.

After these resources are provisioned, the Azure App Service will be able to communicate with the specified on-premises service via the Hybrid Connection, without requiring direct network connectivity between Azure and the private datacenter.

Remember, the above code is a starting point. You may need additional configurations and policies specific to your environment and security requirements. For example, the hostname and port are placeholders; you'd replace those with the actual values corresponding to your datacenter's services.