add HTTP lua filter config (#224)

Signed-off-by: Matt Klein <mklein@lyft.com>

api/filter/http/BUILD

@@ -12,6 +12,7 @@ proto_library(
         "health_check.proto",
         "http_connection_manager.proto",
         "ip_tagging.proto",
+        "lua.proto",
         "rate_limit.proto",
         "router.proto",
         "transcoder.proto",
@@ -64,6 +65,11 @@ api_proto_library(
     deps = ["//api/filter:accesslog"],
 )
 
+api_proto_library(
+    name = "lua",
+    srcs = ["lua.proto"],
+)
+
 api_proto_library(
     name = "buffer",
     srcs = ["buffer.proto"],

api/filter/http/lua.proto

@@ -0,0 +1,10 @@
+syntax = "proto3";
+
+package envoy.api.v2.filter.http;
+
+// The Lua filter allows for generic scripting in an HTTP filter context.
+// TODO(mattklein123): Link to filter docs.
+message Lua {
+  // The Lua code to execute.
+  string inline_code = 1;
+}