MCPX MCP Gateway

local http = require('http') RETRY_TIMEOUT = tonumber(os.getenv("LUNAR_RETRY_REQUEST_TIMEOUT_SEC")) or 100 GATEWAY_BIND_PORT = os.getenv("BIND_PORT") or "8000" local function get_env_number(var_name, default) local value = os.getenv(var_name) local num_value = tonumber(value) if num_value == nil then return default end return num_value end local function add_lunar_generated_header(headers) headers["x-lunar-generated"] = "true" end local function parse_headers(headers) if not headers then return {} -- Return empty table immediately end local parsed_headers = {} for header in string.gmatch(headers, "([^\n]+)") do local key_value = string.gmatch(header, "[^:]+") parsed_headers[key_value(0)] = key_value(1) end return parsed_headers end local function parse_req_headers(headers) if not headers then return {} -- Return empty table immediately end local parsed_headers = {} for line in headers:gmatch("[^\r\n]+") do local key, value = line:match("^([%w%-]+):%s*(.*)$") if key then parsed_headers[key:lower()] = value end end return parsed_headers end local function copyTable(t) if type(t) ~= "table" then return nil end local r = {} for k, v in pairs(t) do if type(v) == "table" then r[k] = copyTable(v) else r[k] = v end end return r end core.register_service("mock_response", "http", function(applet) local headers = applet.f:var("txn.lunar.response_headers") local response_body = applet.f:var("txn.lunar.response_body") local parsed_headers = parse_headers(headers) add_lunar_generated_header(parsed_headers) for key, value in pairs(parsed_headers) do applet:add_header(key, value) end applet:set_status(applet.f:var("txn.lunar.status_code")) applet:start_response() applet:send(response_body) end) core.register_service("generate_request", "http", function(a_http) local headers = a_http.f:var("req.lunar.request_headers") local modified_body = a_http.f:var("req.lunar.request_body") or "" local parsed_headers = parse_headers(headers) local method = a_http.method local dest_addr = a_http.f:var("txn.scheme") .. "://" .. a_http.f:var("req.host_ip") .. ":" .. a_http.f:var("txn.dst_port") .. "/" .. a_http.f:var("txn.path") local res, err = http.send(method, {url=dest_addr, headers=parsed_headers, data=modified_body}) http.response.create{status_code=res.status_code, content=res.content}:send(a_http) end) core.register_action("modify_headers", { "http-req" }, function(txn) local headers = txn.f:var("req.lunar.request_headers") for key, value in pairs(parse_headers(headers)) do txn.http:req_set_header(key, value) end end, 0) core.register_service("modify_request", "http", function(applet) -- Get the modified request details from variables or fallback to original values local headers = applet.f:var("req.lunar.request_headers") or "" local parsed_headers = parse_headers(headers) -- read the pre-captured body (or default to empty string) local new_body = applet.f:var("req.lunar.request_body") or "" local method = applet.f:var("txn.lunar.method") or applet.method local new_host = applet.f:var("req.lunar.request_host") or applet.f:var("txn.host") local new_path = applet.f:var("req.lunar.request_path") or applet.f:var("txn.path") local query = applet.f:var("req.lunar.request_query_params") or "" if query ~= "" then query = "?" .. query end -- Set the x-lunar-host header to the target host parsed_headers["x-lunar-internal"] = "true" parsed_headers["x-lunar-host"] = new_host parsed_headers["x-lunar-scheme"] = applet.f:var("txn.scheme") parsed_headers["x-lunar-lua-handled"] = "true" applet:set_var("txn.url", new_host .. new_path) applet:set_var("txn.host", new_host) applet:set_var("txn.path", path) applet:set_var("txn.lua_handled", "true") -- Send the request to the proxy (localhost:8000) local proxy_url = "http://127.0.0.1:" .. GATEWAY_BIND_PORT .. new_path .. query local res, err = http.send(method, { url = proxy_url, headers = parsed_headers, data = new_body, timeout=RETRY_TIMEOUT }) if err then applet:set_status(500) applet:start_response() applet:send("Error sending request to proxy: " .. err) return end -- Forward the response to the client applet:set_status(res.status_code) if res.headers then for k, v in pairs(res.headers) do if type(v) == "string" then applet:add_header(k, v) elseif type(v) == "table" then for _, single_value in ipairs(v) do if type(single_value) == "string" then applet:add_header(k, single_value) end end end end end applet:start_response() applet:send(res.content or "") end) core.register_action("modify_response", { "http-res" }, function(txn) local headers = txn.f:var("res.lunar.response_headers") local parsed_headers = parse_headers(headers) local status_code = txn.f:var("res.lunar.status_code") or txn.status or 200 local with_body = txn.f:var("res.lunar.with_response_body") with_body = with_body == "true" if with_body then local modified_body = txn.f:var("res.lunar.response_body") or "" txn:done({ status = status_code, headers = parsed_headers, body = modified_body }) else -- If no body modification, just update headers and status code for key, value in pairs(parsed_headers) do txn.http:res_set_header(key, value) end txn.http:res_set_status(status_code) end end, 0) core.register_action("retry_request", { "http-res" }, function(txn) local query = txn.f:var("txn.lunar.query_params") or "" if query ~= "" then query = "?" .. query end local dest_addr = "http://127.0.0.1:" .. GATEWAY_BIND_PORT .. txn.f:var("txn.path") .. query local method = tostring(txn.f:var("txn.lunar.method")) local modified_body = txn.f:var("txn.lunar.request_body") or "" local headers = txn.f:var("txn.lunar.request_headers_str") local parsed_headers = parse_req_headers(headers) parsed_headers["x-lunar-sequence-id"] = txn.f:var("txn.lunar_sequence_id") parsed_headers["x-lunar-scheme"] = txn.f:var("txn.scheme") parsed_headers["x-lunar-internal"] = "true" parsed_headers["x-lunar-retry-attempt"] = "true" local res, err = http.send(method, {url=dest_addr, headers=parsed_headers, data=modified_body, timeout=RETRY_TIMEOUT}) if err then core.Warning("Got an error when retrying request: " .. err) core.Info("Please verify that the timeout is set correctly current value: " .. tostring(RETRY_TIMEOUT)) txn:done({status = 500}) end local content = res.content or "" res.headers["x-lunar-internal"] = "false" txn:done({ status = res.status_code, headers = copyTable(res.headers) or {}, body = content, }) end, 0)