The config of my cluster is as below:

  clusters:
  - name: service_addmachine
    connect_timeout: 30s
    type: STATIC
    lb_policy: ROUND_ROBIN
    load_assignment:
      cluster_name: service_addmachine
      endpoints:
      - lb_endpoints:
        - endpoint:
            address:
              socket_address:
                address: 127.0.0.1
                port_value: 20000
          metadata:
            filter_metadata:
              envoy.lb:
                canary: 0
        - endpoint:
            address:
              socket_address:
                address: 127.0.0.1
                port_value: 20001
          metadata:
            filter_metadata:
              envoy.lb:
                canary: 1

Now I want to set the value of canary in the Lua filter so that requests can be routed to the correct endpoint.

          - name: envoy.filters.http.lua
            typed_config:
              "@type": type.googleapis.com/envoy.extensions.filters.http.lua.v3.Lua
              default_source_code:
                inline_string: |
                  function envoy_on_request(request_handle)
                    local ori = request_handle:streamInfo():dynamicMetadata():get("envoy.filters.http.jwt_authn")
                    local mark = 0
                    if not ori == nil then
                      mark = 1
                    end
                      -- HOW TO CODE HERE???
                      -- request_handle:streamInfo():dynamicMetadata():set("envoy.filters.http.router", "envoy.lb", {canary=mark})
                      -- request_handle:streamInfo():dynamicMetadata():set("envoy.lb", "canary", mark)
                      -- request_handle:metadata():set("envoy.lb", "canary", mark)
                  end

I’ve read the official doc about Lua filter: https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_filters/lua_filter

The doc says that we could set the value of envoy.lb. But the requests can’t be routed to the correct endpoint even if there is no grammar error of Lua filter with my config above.

So, it doesn’t seem that I could set the value of canary in the Lua filter?