Using kubernetes gateway.solo.io with crdb.cockroachlabs.com

Question

Pulumi · Accepted Answer

To use a Kubernetes Gateway API with an external data service like CockroachDB provided by `crdb.cockroachlabs.com`, you need to define a Kubernetes gateway resource in your cluster that can manage incoming traffic and route it appropriately to your services. For demonstration, let's configure a simple setup where we use the Gateway API to direct traffic to a Kubernetes service that could theoretically connect to a CockroachDB instance.

First, ensure you have the `kubernetes` package from Pulumi, which allows you to work with resources in a Kubernetes cluster. The Kubernetes Gateway API is an evolving standard and is part of the `networking.v1alpha1` API group in Kubernetes. However, since Pulumi supports custom resources, you can define the resources as long as you have the corresponding Custom Resource Definitions (CRDs) applied to your cluster for `Gateway` and `HTTPRoute`.
 
Here is a basic guide on how you might define a `Gateway` and `HTTPRoute` for routing traffic to a Kubernetes service, assuming that the service would then communicate with CockroachDB:

1. **Gateway**: This resource configures a load balancer for HTTP traffic according to specific labels matching services.
2. **HTTPRoute**: Routes describe how traffic to a certain host or path should be forwarded. Used in conjunction with the Gateway resource.

I will now show you a Pulumi TypeScript program that sets up a simple Gateway and HTTPRoute. The specific configurations related to CockroachDB are context-dependent and would require more details on how your application interfaces with the CockroachDB instance.

```typescript
import * as k8s from '@pulumi/kubernetes';

const gatewayName = 'my-gateway';
const namespaceName = 'default'; // Replace with the namespace of your service if different

// Configure a Gateway for HTTP traffic
const gateway = new k8s.networking.v1alpha1.Gateway(gatewayName, {
    metadata: {
        name: gatewayName,
        namespace: namespaceName,
    },
    spec: {
        gatewayClassName: 'my-gateway-class', // Ensure you have a GatewayClass with this name in your cluster
        listeners: [
            {
                port: 80,
                protocol: 'HTTP',
                name: 'http',
                allowedRoutes: {
                    namespaces: {
                        from: 'All',
                    },
                },
            },
        ],
    },
});

// Define an HTTPRoute to manage incoming HTTP requests to the Gateway
const httpRoute = new k8s.networking.v1alpha1.HTTPRoute('my-http-route', {
    metadata: {
        name: 'http-route',
        namespace: namespaceName,
    },
    spec: {
        gateways: {
            allow: 'All',
        },
        hostnames: ['your-app-domain.com'], // Replace with your domain
        rules: [
            {
                matches: [
                    {
                        path: {
                            type: 'Prefix',
                            value: '/',
                        },
                    },
                ],
                forwardTo: [
                    {
                        serviceName: 'your-service-name', // Replace with the name of your Kubernetes service
                        port: 26257, // Default CockroachDB secure port; replace if needed
                    },
                ],
            },
        ],
    },
});

// Export the gateway and route URLs
export const gatewayUrl = gateway.metadata.name;
export const httpRouteUrl = httpRoute.metadata.name;
```

Before you can successfully run this program, make sure the following requirements are met:
- You must have the Gateway API CRDs installed in your Kubernetes cluster.
- A `GatewayClass` with the name provided in the Gateway must already be defined in your cluster.
- The forward-to `serviceName` and `port` must correspond to a Kubernetes Service that can connect to your CockroachDB instance.
- Ensure the `hostnames` match the domain you intend to route traffic from.

This program defines two essential resources for managing ingress traffic to a service within your Kubernetes cluster. The `Gateway` defines an entry point for traffic, specifying the type of protocol (HTTP) and the port on which it accepts traffic. The associated `HTTPRoute` routes incoming requests to the appropriate service based on hostname and path matching rules.

Once everything is set-up, any traffic going to 'your-app-domain.com' will be routed by the Gateway through the `HTTPRoute` to a service named 'your-service-name' which is expected to communicate with CockroachDB on the specified port.

Be aware that actual routing to CockroachDB and establishing a connection will require proper service configuration that knows how to use CockroachDB's client. This might also involve secret management for database credentials and other configurations related to CockroachDB itself, which is outside the scope of this example and highly specific to your application's needs.

Additionally, if you haven't already, consider reviewing the official [Gateway API documentation](https://gateway-api.sigs.k8s.io/) for Kubernetes and the [CockroachDB documentation](https://www.cockroachlabs.com/docs/) for specifics on how to deploy and connect to CockroachDB.