envoy - listener, route, cluster and endpoint
It become important to understand envoy mechanics and this is an awesome illustration of it and how these listeners and cluster and endpoints are linked together. 1. Listener (Where traffic enters) A Listener is a named network location (an IP address and a port) that Envoy opens up to accept incoming connections from clients. What it does: It's the "front door." It listens for incoming traffic, handles TLS decryption (if configured), and passes the request down the chain. In Istio: When you create an Istio Gateway resource and specify port 80 or 443 , Istio tells Envoy to open a Listener on that port. Real-world analogy: The receptionist desk at a building entrance. 2. Route (How traffic is matched) Once a request enters through a Listener, Envoy needs to decide what to do with it. This is where the Route comes in. What it does: It inspects the request details—like the URI path ( /html vs /status/200 ), HTTP methods ( GET , POST ), or he...
