Introduction

When deploying microservices on Kubernetes, secure communication between services is a critical aspect. Istio, a popular service mesh, simplifies managing communication across microservices with added security and resilience features. One such feature is the ingress gateway, which acts as a unified entry point into the service mesh, handling inbound traffic from external sources. This article explores the concept of using one `istio-ingressgateway` and multiple TLS gateways, explaining how they can be utilized to improve security and performance in your Kubernetes environment.

Istio-Ingressgateway Overview

In Istio, the ingress gateway is a component that manages inbound HTTP/S traffic. It allows finer control over traffic flowing into the service mesh, and can route requests based on various factors such as hostname, URI path, and more.

Key Components of Istio-Ingressgateway

• Gateway Resource: Defines the ports, protocols, and other settings for incoming traffic.
• VirtualService Resource: Specifies detailed routing rules for requests passing through the gateway.
• DestinationRule Resource: Contains configurations for traffic policies to apply to a service once it is inside the mesh.

TLS Configuration with Multiple Gateways

Implementing TLS at the ingress level involves configuring multiple TLS gateway resources. By using multiple gateways, you can separate concerns and manage configurations per domain or service, allowing for a cleaner, modular configuration.

Setting Up a Single `istio-ingressgateway`

Before creating multiple TLS gateways, ensure you have a single `istio-ingressgateway` deployed in your cluster, typically done upon installing Istio. This `istio-ingressgateway` is a Kubernetes `Service` that exposes the ingress functionalities.

Defining Multiple TLS Gateways

To define multiple TLS gateways, create distinct gateway resources for each use case. This allows for flexibility and aligns with best practices like separation of traffic types (HTTP vs HTTPS), environments, or services.

Example Configuration

Below is a basic example illustrating how to set up multiple TLS gateways:

1. Gateway A for Domain A:

• port:
  • "domain-a.com"
• port:
  • "domain-b.com"
• "domain-a.com"
• domain-a-gateway
• match:
  • uri:
  • destination:
• Isolation: Separates inbound traffic configuration among different domains or services.
• Security: Enhanced security with specific TLS credentials for each domain/service.
• Flexibility: Independent configuration for scaling, monitoring, and updates per gateway.