What language that envoy proxy uses?

Question

What is the programming language that below envoy uses?

  operation: INSERT_BEFORE
  value: # lua filter specification
   name: envoy.lua
   config:
     inlineCode: |
       function envoy_on_request(request_handle)
         -- Make an HTTP call to an upstream host with the following headers, body, and timeout.
         local headers, body = request_handle:httpCall(
          "lua_cluster",
          {
           [":method"] = "POST",
           [":path"] = "/acl",
           [":authority"] = "internal.org.net"
          },
         "authorize call",
         5000)
       end

Is it possible to use python in place of above language?

Answer 1

It is called Lua. Read more here.