envoy_lua_cookie_to_metadata.yaml

http_filters:
- name: envoy.lua
  typed_config:
    "@type": "type.googleapis.com/envoy.extensions.filters.http.lua.v3.Lua"
    inline_code: |
      function stringSplit(inputstr, sep)
        if sep == nil then
          sep = "%s"
        end
        local t={}
        for str in string.gmatch(inputstr, "([^"..sep.."]+)") do
          table.insert(t, str)
        end
        return t
      end
      function envoy_on_request(request_handle)
        -- 
        -- cookies name to save in metadata
        -- 
        local cookiesArray = {"CID"}
        local cookie = request_handle:headers():get("cookie")
        local dynamicMetadata = request_handle:streamInfo():dynamicMetadata()

        if cookie ~= nil then
          local splitCookieString = stringSplit(cookie, ";")
          for i, cookieItem in ipairs(splitCookieString) do
            for y, cookiesItem in ipairs(cookiesArray) do
              if string.find(cookieItem, cookiesItem) ~= nil then
                local cookieKV = stringSplit(cookieItem, "=")
                local cookieName = string.gsub(cookieKV[1], "%s+", "")
                dynamicMetadata:set("envoy.filters.http.lua.cookie", cookieName, cookieKV[2])
              end
            end
          end
        end
      end

envoy v1.15 (stable) can't use cookie in header_to_metadata extension (this available in latest envoy only) https://www.envoyproxy.io/docs/envoy/v1.15.2/api-v3/extensions/filters/http/header_to_metadata/v3/header_to_metadata.proto#extensions-filters-http-header-to-metadata-v3-config-rule

to use cookie in metadata - you can use Lua extension and add it in http_filters - for example this code will add cookie name CID to metadata envoy.filters.http.lua.cookie to test this code - you add to access log %DYNAMIC_METADATA(envoy.filters.http.lua.cookie)%

access_log:
- name: envoy.access_loggers.file
  typed_config:
    "@type": type.googleapis.com/envoy.extensions.access_loggers.file.v3.FileAccessLog
    path: /dev/stdout
    log_format:
      json_format:
        protocol: "%PROTOCOL%"
        duration: "%DURATION%"
        response_code: "%RESPONSE_CODE%"
        response_flags: "%RESPONSE_FLAGS%"
        x_request_id: "%REQ(X-REQUEST-ID)%"
        meta_cookies: "%DYNAMIC_METADATA(envoy.filters.http.lua.cookie)%"

to get ratelimit service with cookie name

rate_limits:
- actions:
  - dynamic_metadata:
      descriptor_key: "cookie-cid"
      metadata_key:
        key: envoy.filters.http.lua.cookie
        path:
        - key: CID