envoy - using lua with http requests

Here we will use an envoy configuration that allow us to run lua scripts to intercept http request. This static configuration 

static_resources:

  listeners:

  - name: listener_0

    address:

      socket_address:

        address: 0.0.0.0

        port_value: 8080

    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: ingress_http

          codec_type: AUTO

          route_config:

            name: local_route

            virtual_hosts:

            - name: backend

              domains: ["*"]

              routes:

              - match: { prefix: "/" }

                route:

                  cluster: httpbin

          http_filters:

          - name: envoy.filters.http.lua

            typed_config:

              "@type": type.googleapis.com/envoy.extensions.filters.http.lua.v3.Lua

              inline_code: |

                function envoy_on_request(request_handle)

                  request_handle:logInfo("Lua filter: Request received")

                  request_handle:headers():add("x-added-by", "lua-filter")

                end

                function envoy_on_response(response_handle)

                  response_handle:logInfo("Lua filter: Response processing")

                  response_handle:headers():add("x-response-added-by", "lua-filter")

                end

          - name: envoy.filters.http.router

            typed_config:

              "@type": type.googleapis.com/envoy.extensions.filters.http.router.v3.Router

  clusters:

  - name: httpbin

    connect_timeout: 5s

    type: LOGICAL_DNS

    lb_policy: ROUND_ROBIN

    load_assignment:

      cluster_name: httpbin

      endpoints:

      - lb_endpoints:

        - endpoint:

            address:

              socket_address:

                address: httpbin.org

                port_value: 80

    dns_lookup_family: V4_ONLY

To run this via docker we simply do the following:- 

docker run --rm -it -v ".\envoy-lua.yaml:/etc/envoy/envoy.yaml"

-p 8080:8080 envoyproxy/envoy:v1.31-latest

As you can see from the static configuration, we are using port 8080. 

To test this out, run 

curl -v http://localhost:8080/get

And you should be able to see the following responses from envoy.