Istio-Enabled Canary Deployments for Machine Learning Models

Question

Pulumi · Accepted Answer

Canary deployment is a strategy for deploying new versions of software incrementally to a small subset of users before making the software available to the entire user base. When deploying machine learning models, this strategy can be particularly valuable as it enables you to test the performance and behavior of new models in a production setting while limiting the risk.

Istio is a service mesh that can be used in Kubernetes environments to manage microservices in a consistent way. It provides advanced traffic routing capabilities that can enable canary deployments. By adjusting Istio's routing rules, you can direct a small amount of traffic to a new version of your service—where the new machine learning model is running—and compare the performance with the current version.

To set up a canary deployment for machine learning models with Istio, you'd typically do the following with Pulumi:

1. Deploy Kubernetes clusters and configure Istio on them.
2. Deploy your machine learning models as services within the cluster.
3. Configure Istio’s traffic routing to distribute a small percentage of requests to the new model and analyze the results.

It's worth noting that Pulumi does not have Istio-specific constructs, but it can help orchestrate the deployment and configuration of Kubernetes resources that are available as part of the Istio installation.

Below is an outline of a Pulumi program written in Python that sets up the scaffolding of a canary deployment for machine learning models on a Kubernetes cluster with Istio:

```python
import pulumi
import pulumi_kubernetes as k8s

# Initiate the Pulumi Kubernetes provider to interact with your cluster.
# This assumes you have already set up your Kubernetes cluster and have `kubectl`
# configured to connect to it.
k8s_provider = k8s.Provider("k8s")

# Apply the Istio manifests to the cluster.
# These manifests should be customized to enable the functionality required
# for canary deployments (like Istio's VirtualService, DestinationRule, etc.).
# You can find the specific Istio configuration that is relevant for canary deployments
# in the Istio documentation: https://istio.io/latest/docs/concepts/traffic-management/
istio_manifest = k8s.yaml.ConfigFile("istio", "path_to_istio_manifest.yaml", provider=k8s_provider)

# Machine learning model deployment as a Kubernetes service.
# This is a simplified example that would need to be replaced with the actual
# deployment of your model as a microservice.
ml_model_v1 = k8s.apps.v1.Deployment(
    "ml-model-v1",
    spec={ # Define your machine learning model microservice spec here },
    provider=k8s_provider,
)

ml_model_v2 = k8s.apps.v1.Deployment(
    "ml-model-v2",
    spec={ # Define the new version of your machine learning model microservice spec here },
    provider=k8s_provider,
)

# Define a Kubernetes service that exposes your machine learning models.
ml_model_service = k8s.core.v1.Service(
    "ml-model-service",
    spec={
        "selector": {"app": "ml-model"},
        "ports": [{"protocol": "TCP", "port": 80}],
    },
    provider=k8s_provider,
)

# Define configuration for routing a subset of traffic to the canary (new model version).
canary_route = k8s.networking.v1alpha3.VirtualService(
    "canary-route",
    metadata={"name": "ml-model-route"},
    spec={
        "hosts": ["ml-model-service"],
        "http": [{
            "route": [
                {"destination": {"host": "ml-model-v1", "subset": "v1"}, "weight": 90},
                {"destination": {"host": "ml-model-v2", "subset": "v2"}, "weight": 10},
            ]
        }],
    },
    provider=k8s_provider,
)

# Export any output you find necessary, for example the service URL.
pulumi.export("model_service_url", ml_model_service.status.apply(lambda status: status.load_balancer.ingress[0].ip))
```

This Pulumi program achieves the following:

- It utilizes the existing Kubernetes cluster and provides a ready-to-go Istio setup by applying `istio_manifest.yaml`. You must modify this to suit your installation and Istio preferences.
- It deploys two versions of your machine learning model (`ml_model_v1` and `ml_model_v2`) as Kubernetes deployments.
- It sets up a Kubernetes service `ml_model_service` that abstracts both deployment versions behind a single endpoint.
- It uses the Istio VirtualService resource to route traffic between the two deployment versions, with a specified percentage of traffic going to each—90% to the stable version (v1) and 10% to the canary version (v2).
- It exports the service URL once it's up and running.

Please ensure you have the correct Kubernetes and Istio configurations, as well as the machine learning model service definitions, to implement this in a real-world scenario. This outline needs to be populated with the actual application, networking resource definitions, and the details of how your model is packaged as a microservice.