What is Envoy

• Listeners: accept connections on a port
• Filters: chain handlers (HTTP filter, network filter)
• Clusters: groups of upstream servers
• xDS API: dynamic config (CDS, LDS, RDS, EDS) over gRPC
• Admin API: :9901 for stats, config dump, health

# Envoy listener config
listeners:
- address:
    socket_address: { address: 0.0.0.0, port_value: 80 }
  filter_chains:
  - filters:
    - name: envoy.filters.network.http_connection_manager
      typed_config:
        stat_prefix: ingress_http
        route_config:
          name: local_route
          virtual_hosts:
          - name: backend
            domains: ["*"]
            routes:
            - match: { prefix: "/" }
              route: { cluster: service_backend }

• Service Mesh
• Istio

When comparing Envoy to other popular proxy solutions like nginx and HAProxy, several key differences emerge that highlight Envoy's unique capabilities.

Firstly, Envoy is designed as a layer 7 proxy, which means it operates at the application layer of the OSI model, allowing for advanced features such as HTTP/2 and gRPC support. In contrast, while nginx and HAProxy can handle layer 7 traffic, they are traditionally optimized for layer 4, which may limit their capabilities in microservices environments.

Secondly, Envoy provides built-in service discovery and dynamic configuration through the xDS API. This allows it to adapt to changes in the service landscape without requiring a restart, unlike nginx and HAProxy, which typically rely on static configurations.

Furthermore, Envoy's advanced routing capabilities enable features like traffic shadowing, retries, and circuit breaking, enhancing resilience and observability. These features are essential for modern cloud-native applications that require high availability and performance.

In summary, while nginx and HAProxy are robust solutions for traditional web applications, Envoy's focus on microservices architecture, dynamic configuration, and advanced observability features make it a superior choice for contemporary cloud environments.