front-envoy.yaml

# The static_resources block contains definitions for clusters and listeners that aren’t dynamically managed
static_resources:
  listeners:
  # Listener configured to listen on port 80
  - address:
      socket_address:
        address: 0.0.0.0
        port_value: 80
    # Listner's filter chain is configured that Envoy to manage HTTP traffic.
    filter_chains:
    - filters:
      - name: envoy.http_connection_manager
        config:
          codec_type: auto
          stat_prefix: ingress_http
          route_config:
            name: local_route
            # Virtual host configures to accept traffic for all domains.
            # With Routes, mapping traffic for /service/blue, /service/green, and /service/red to the appropriate clusters.
            virtual_hosts:
            - name: backend
              domains:
              - "*"
              routes:
              - match:
                  prefix: "/service/blue"
                route:
                  cluster: service_blue
              - match:
                  prefix: "/service/green"
                route:
                  cluster: service_green
              - match:
                  prefix: "/service/red"
                route:
                  cluster: service_red
          http_filters:
          - name: envoy.router
            config: {}
  # Static Clouster configurations:
  # You can configure timeouts, circuit breakers, discovery settings, and more on clusters
  # Clusters are composed of endpoints – a set of network locations that can serve requests for the cluster. 
  # In this example, endpoints are canonically defined in DNS, which Envoy can read from. 
  # Endpoints can also be defined directly as socket addresses, or read dynamically via the Endpoint Discovery Service.
  clusters:
  - name: service_blue
    connect_timeout: 0.25s
    type: strict_dns
    lb_policy: round_robin
    http2_protocol_options: {}
    hosts:
    - socket_address:
        address: service_blue
        port_value: 80
  - name: service_green
    connect_timeout: 0.25s
    type: strict_dns
    lb_policy: round_robin
    http2_protocol_options: {}
    hosts:
    - socket_address:
        address: service_green
        port_value: 80
  - name: service_red
    connect_timeout: 0.25s
    type: strict_dns
    lb_policy: round_robin
    http2_protocol_options: {}
    hosts:
    - socket_address:
        address: service_red
        port_value: 80
admin:
  access_log_path: "/dev/null"
  # The address object tells Envoy to create an admin server listening on port 8001.
  address:
    socket_address:
      address: 0.0.0.0
      port_value: 8001