How Do I Configure a Kubernetes Networking.istio.io EnvoyFilter With Pulumi?

Introduction

In this guide, we will explore how to configure an EnvoyFilter for Istio workloads using Pulumi. The EnvoyFilter resource is a powerful tool that allows you to customize the behavior of the Envoy proxy, which is integral to the Istio service mesh. By using Pulumi, a modern infrastructure as code platform, you can automate and manage your Kubernetes resources efficiently. In this example, we will demonstrate how to define an EnvoyFilter to modify HTTP headers of incoming requests, showcasing the flexibility and control you can achieve over network traffic in your Kubernetes cluster.

Key Points:

1. Pulumi and Kubernetes Integration: Utilize Pulumi’s Kubernetes provider to manage and automate Kubernetes resources.
2. Istio EnvoyFilter: Create an EnvoyFilter to manipulate HTTP headers, showcasing the customization capabilities of Istio.
3. TypeScript: Implement the solution using TypeScript for a robust and type-safe development experience.

Step-by-Step Explanation:

1. Import Necessary Packages: Start by importing the Pulumi and Kubernetes packages. These libraries will enable you to define and manage your Kubernetes resources with Pulumi.

2. Define the Kubernetes Namespace: Specify the namespace where the EnvoyFilter will be applied. In this example, we use the “istio-system” namespace, which is commonly used for Istio components.

3. Create the EnvoyFilter Resource: Define the EnvoyFilter resource. This involves specifying the workload selector to target specific workloads and configuring patches to modify HTTP headers. The example demonstrates adding a custom header to incoming requests using a Lua script.

import * as pulumi from "@pulumi/pulumi";
import * as k8s from "@pulumi/kubernetes";

// Define the namespace where the EnvoyFilter will be applied
const namespace = new k8s.core.v1.Namespace("istio-system", {
    metadata: {
        name: "istio-system",
    },
});

// Define the EnvoyFilter resource
const envoyFilter = new k8s.apiextensions.CustomResource("envoyFilter", {
    apiVersion: "networking.istio.io/v1alpha3",
    kind: "EnvoyFilter",
    metadata: {
        name: "my-envoyfilter",
        namespace: namespace.metadata.name,
    },
    spec: {
        workloadSelector: {
            labels: {
                app: "my-app",
            },
        },
        configPatches: [
            {
                applyTo: "HTTP_FILTER",
                match: {
                    context: "SIDECAR_INBOUND",
                    listener: {
                        filterChain: {
                            filter: {
                                name: "envoy.http_connection_manager",
                                subFilter: {
                                    name: "envoy.router",
                                },
                            },
                        },
                    },
                },
                patch: {
                    operation: "INSERT_BEFORE",
                    value: {
                        name: "envoy.filters.http.lua",
                        typed_config: {
                            "@type": "type.googleapis.com/envoy.extensions.filters.http.lua.v3.Lua",
                            inlineCode: `
                                function envoy_on_request(request_handle)
                                    request_handle:headers():add("x-custom-header", "my-value")
                                end
                            `,
                        },
                    },
                },
            },
        ],
    },
});

// Export the namespace and EnvoyFilter names
export const namespaceName = namespace.metadata.name;
export const envoyFilterName = envoyFilter.metadata.name;

Conclusion

In this guide, we successfully configured a Kubernetes EnvoyFilter for Istio workloads using Pulumi. By defining the EnvoyFilter, we were able to add a custom HTTP header to incoming requests. This example highlights the power and flexibility of using Pulumi to manage Kubernetes resources, allowing for precise control over network traffic within an Istio-managed environment. By leveraging Pulumi’s infrastructure as code capabilities, you can streamline your deployment processes and ensure consistent configurations across your Kubernetes clusters.