Envoy Proxy provides a range of filters and plugins that can be used to customize its behavior to meet the specific needs of your application. One useful filter is envoy.filters.network.direct_response, which can be used to instruct Envoy to reply with a static response and fixed HTTP response code. This can be useful in situations where you need to return a response without forwarding the request to the intended service, such as for health checks or service monitoring. With this filter, you can easily configure Envoy to return a predefined response with a fixed HTTP status code, simplifying the management of your application and reducing the load on your services.
Let’s create an Envoy container with a direct response filter, add the direct_response filter to the network filter chain, and configure it to return the desired status response.
$ mkdir envoy $ cd envoy
Create an Envoy configuration file called envoy-fixed-response-1.yaml with the contents provided below.
static_resources:
listeners:
- name: listener_0
address:
socket_address:
address: 0.0.0.0
port_value: 8000
filter_chains:
- filters:
- name: envoy.filters.network.http_connection_manager
typed_config:
"@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
stat_prefix: envoy-fixed-response-1
http_filters:
- name: envoy.filters.http.router
typed_config:
"@type": type.googleapis.com/envoy.extensions.filters.http.router.v3.Router
route_config:
name: route-1
virtual_hosts:
- name: direct_response_service
domains: ["*"]
routes:
- match:
prefix: "/"
direct_response:
status: 200
body:
inline_string: "This is a direct response from envoy-fixed-response-1 container"
Create a Docker compose configuration file called docker-compose.yaml with the contents provided below.
version: '3'
services:
envoy-fixed-response-1:
image: envoyproxy/envoy:v1.25.1
container_name: envoy-fixed-response-1
ports:
- "8000:8000"
volumes:
- ./envoy-fixed-response-1.yaml:/etc/envoy/envoy.yaml
networks:
envoy:
ipv4_address: 10.10.0.11
networks:
envoy:
driver: bridge
ipam:
config:
- subnet: 10.10.0.0/16
Start the Docker container.
$ docker-compose up -d
You should be able to see a fixed response being returned from Envoy.
$ curl localhost:8000 This is a direct response from envoy-fixed-response-1 container