Choosing Between Envoy and NGINX Ingress Controllers for Kubernetes

As Kubernetes has become the standard for deploying containerized applications, ingress controllers play a critical role in managing how external traffic is routed to services within the cluster. Envoy and NGINX are two of the most popular options for ingress controllers, and each has its strengths, weaknesses, and ideal use cases.

In this blog, we’ll explore:

1. How both ingress controllers work.
2. A detailed comparison of their features.
3. When to use Envoy vs. NGINX for ingress management.

---

What is an Ingress Controller?

An ingress controller is a specialized load balancer that:

• Manages incoming HTTP/HTTPS traffic.
• Routes traffic to appropriate services based on rules defined in Kubernetes ingress resources.
• Provides features like TLS termination, path-based routing, and host-based routing.

---

How Envoy Ingress Controller Works

Envoy, initially built by Lyft, is a high-performance, modern service proxy and ingress solution. Here's how it operates in Kubernetes:

1. Ingress Resource: You define Kubernetes ingress resources, specifying rules for routing traffic (e.g., path-based, host-based).
2. Dynamic Configuration:
   • The Envoy Ingress Controller watches for changes to ingress resources and updates its configuration in real time.
   • Uses Envoy’s xDS (dynamic configuration) APIs to manage routes, clusters, and listeners dynamically without restarting.
3. Traffic Handling:
   • External traffic reaches Envoy, usually through a LoadBalancer service.
   • Envoy evaluates ingress rules, applies filters (e.g., rate limiting, retries), and forwards traffic to the appropriate service.

Unique Features of Envoy:

• Advanced load balancing (e.g., consistent hashing, weighted round-robin).
• Built-in retries, timeouts, circuit breakers, and fault injection.
• Native support for HTTP/2, gRPC, and WebSockets.
• Advanced observability with metrics (Prometheus), logging, and distributed tracing (Zipkin/Jaeger).
• Rich security features like mTLS and role-based access control (RBAC).

---

How NGINX Ingress Controller Works

NGINX, widely known as a web server and reverse proxy, also serves as a robust ingress controller:

1. Ingress Resource:
   • Similar to Envoy, you define ingress resources in Kubernetes for routing traffic.
2. Configuration Reloads:
   • The NGINX Ingress Controller translates ingress rules into NGINX configuration files.
   • For certain changes, it may reload its configuration, briefly interrupting traffic.
3. Traffic Handling:
   • Traffic flows through NGINX, which routes it to services based on defined ingress rules.
   • Features include path-based routing, host-based routing, TLS termination, and basic authentication.

Unique Features of NGINX:

• Mature and widely used for traditional web applications.
• Good for scenarios requiring basic ingress functionality.
• Simpler setup compared to Envoy, making it beginner-friendly.

---

Feature Comparison: Envoy vs. NGINX

Feature	Envoy Ingress Controller	NGINX Ingress Controller
Performance	Optimized for microservices, HTTP/2, gRPC, WebSockets	Optimized for traditional web apps and HTTP/1.1
Dynamic Configuration	Fully dynamic via xDS APIs, no reload required	Requires reload for some configuration changes
Protocol Support	HTTP/1.1, HTTP/2, gRPC, WebSockets	HTTP/1.1, WebSockets
Resilience Features	Retries, circuit breaking, fault injection	Basic retries and failover
Observability	Rich metrics, distributed tracing, logging	Basic metrics and logging
Rate Limiting	Highly configurable, dynamic	Limited, not as flexible
Service Mesh Support	Core proxy in service meshes (e.g., Istio)	Requires integration with external service meshes
Ease of Use	More complex, better for advanced use cases	Simpler, good for basic setups
Security	Full mTLS, RBAC, and advanced security filters	TLS termination, basic authentication
Load Balancing	Advanced (e.g., consistent hashing, least requests)	Round-robin and IP hash-based balancing
Community & Ecosystem	Growing, with a focus on cloud-native applications	Mature, widely supported

---

When to Use Envoy Ingress Controller

Envoy is ideal for:

• Microservices Architectures: If your application uses modern protocols like gRPC or requires advanced routing features.
• Dynamic Environments: Ideal for applications with frequent configuration changes, as it supports dynamic updates without restarts.
• Observability Needs: Teams requiring detailed metrics, logging, and distributed tracing.
• Service Mesh Integration: If you're using a service mesh like Istio, Envoy is a natural choice as it’s the default sidecar proxy.
• Advanced Traffic Control: Scenarios requiring fault injection, circuit breaking, or advanced rate limiting.