Secured API Gateways for LLMs with Kubernetes Ingress

Question

Pulumi · Accepted Answer

To create secure API gateways for Large Language Models (LLMs) with Kubernetes Ingress, we are going to define a Kubernetes Ingress resource. An Ingress is an API object that manages external access to services in a cluster, typically HTTP. Ingress may provide load balancing, SSL termination, and name-based virtual hosting.

To secure the Ingress, we will use TLS. For this example, I am assuming that you have a certificate and a corresponding private key for TLS. These will be stored in a Kubernetes Secret resource.

We will be using Pulumi with the Kubernetes provider to define our infrastructure as code.

Here's a structured plan to accomplish this:

1. Define a Kubernetes Service for the LLMs.
2. Create a Kubernetes Secret to store the TLS certificate and key.
3. Define the Ingress resource that uses the TLS Secret for securing the endpoints.

Below is the Pulumi program in Python which will define the necessary Kubernetes resources:

```python
import pulumi
import pulumi_kubernetes as k8s

# Define the Kubernetes Secret for the TLS certificates
tls_secret_name = 'llm-tls-secret'
tls_secret = k8s.core.v1.Secret(
    tls_secret_name,
    metadata={'name': tls_secret_name},
    type='Opaque',
    data={
        'tls.crt': pulumi.FileAsset('path_to_certificate.crt').base64_encode(),
        'tls.key': pulumi.FileAsset('path_to_private_key.key').base64_encode(),
    }
)

# Define the Service for the LLM application
llm_service_name = 'llm-service'
llm_service = k8s.core.v1.Service(
    llm_service_name,
    metadata={'name': llm_service_name},
    spec={
        'selector': {'app': 'llm'},
        'ports': [{'protocol': 'TCP', 'port': 80}]
    }
)

# Define the Ingress resource that uses the TLS secret
llm_ingress_name = 'llm-ingress'
llm_ingress = k8s.networking.v1.Ingress(
    llm_ingress_name,
    metadata={'name': llm_ingress_name},
    spec={
        'tls': [{'hosts': ['example.com'], 'secretName': tls_secret_name}],
        'rules': [{
            'host': 'example.com',
            'http': {
                'paths': [{
                    'path': '/',
                    'pathType': 'Prefix',
                    'backend': {
                        'service': {
                            'name': llm_service.metadata['name'],
                            'port': {'number': 80}
                        }
                    }
                }]
            }
        }]
    }
)

# Export the Ingress endpoint
pulumi.export('ingress_endpoint', llm_ingress.status.apply(lambda status: status.load_balancer.ingress[0].hostname if status.load_balancer.ingress else "Pending"))
```

### Explanation:

- A Kubernetes Secret is created to store the TLS certificate and key, which will be used by the Ingress controller to encrypt the traffic.
- A Kubernetes Service is defined to point traffic to our LLM application, which runs on TCP port 80.
- The Ingress resource is specified with a TLS section referencing the Secret and rules defining how to route traffic.

Please store your certificate and key files at the correct paths (`path_to_certificate.crt` and `path_to_private_key.key`) before running this program, or adjust accordingly.

Please note that in real-world scenarios, certificate management might be handled separately through specialized Kubernetes tools like cert-manager which can provide automatic certificate issuance and rotation.

Remember to change the `'example.com'` to your domain where your LLM service will be accessible from. If your Kubernetes cluster is not yet configured to use an Ingress controller like nginx or traefik, you need to set one up to handle Ingress resources.

After running the Pulumi program, it will output the endpoint of the Ingress under the name `ingress_endpoint`. If it outputs "Pending," it means the cloud provider has not yet assigned an IP or DNS name to the Ingress resource.