Envoy Use Case: WebSockets

Envoy supports tunneling WebSockets over HTTP/2 and above. This feature can be enabled from the console through the advanced section.

info

If you wish to know more about Envoy WebSocket support, visit the official documentation.

Firstly, you will need to configure the microservice, and add the corresponding entry in clusters.yaml. For example:

- "@type": type.googleapis.com/envoy.config.cluster.v3.Cluster
  name: websocket-service
  connect_timeout: 30s
  type: LOGICAL_DNS
  lb_policy: ROUND_ROBIN
  load_assignment:
    cluster_name: websocket-service
    endpoints:
    - lb_endpoints:
      - endpoint:
          address:
            socket_address:
              address: websocket-service
              port_value: 80

Since WebSockets need the configuration of an additional property in the corresponding route, the WebSocket's endpoint cannot be added in the Endpoints section. Instead, you will need to create it through the endpoints.yaml extension file.

- listener_name: frontend
  match: 
    path: "/websocket-route"
  route:
    timeout: 0s
    cluster: websocket-service
    upgrade_configs:
      upgrade_type: websocket

The snippet above adds a frontend endpoint towards the websocket-service configured beforehand. In the property upgrade_configs, you can specify the type of upgrade desired for the corresponding connection, websocket in this case.

danger

The described endpoint is just a simple example to highlight the WebSocket configuration. Remember to edit it if you need additional features (e.g. rewrites, secret resolution, etc.).