fix(request-transformer) correctly construct error message when templ…

…ate throws Lua

error. That way the errr log will contain actual error messages from the
template closure. Previously the `error` function was used incorrectly
and incorrect Lua error was written into the logs instead. Fixes #25

kong/plugins/request-transformer/access.lua

@@ -149,12 +149,12 @@ local function iter(config_array)
 
     local res, err = param_value(current_value, config_array)
     if err then
-      return error("[request-transformer] failed to render the template ",
-        current_value, ", error:", err)
+      return error("[request-transformer] failed to render the template " ..
+                   current_value .. ", error:" .. err)
     end
 
     kong.log.debug("[request-transformer] template `", current_value,
-      "` rendered to `", res, "`")
+                   "` rendered to `", res, "`")
 
     return i, current_name, res
   end, config_array, 0

spec/02-access_spec.lua

@@ -100,6 +100,9 @@ describe("Plugin: request-transformer(access) [#" .. strategy .. "]", function()
       hosts = { "test23.test" },
       paths = { "/request" }
     })
+    local route24 = bp.routes:insert({
+      hosts = { "test24.test" }
+    })
 
     bp.plugins:insert {
       route = { id = route1.id },
@@ -380,6 +383,16 @@ describe("Plugin: request-transformer(access) [#" .. strategy .. "]", function()
       config = {}
     }
 
+    bp.plugins:insert {
+      route = { id = route24.id },
+      name = "request-transformer",
+      config = {
+        add = {
+          headers = { "x-user-agent:$(type(headers[\"User-Agent\"]) == \"table\" and headers[\"User-Agent\"][1] or headers[\"User-Agent\"])", },
+        },
+      }
+    }
+
     assert(helpers.start_kong({
       database = strategy,
       plugins = "bundled, request-transformer",
@@ -1811,6 +1824,26 @@ describe("Plugin: request-transformer(access) [#" .. strategy .. "]", function()
       })
       assert.response(r).has.status(500)
     end)
+    it("rendering error is correctly propagated in error.log, issue #25", function()
+      local r = assert(client:send {
+        method = "GET",
+        path = "/",
+        headers = {
+          host = "test24.test",
+        }
+      })
+      assert.response(r).has.status(500)
+
+      helpers.wait_until(function()
+        local pl_file = require "pl.file"
+
+        local cfg = helpers.test_conf
+        local logs = pl_file.read(cfg.prefix .. "/" .. cfg.proxy_error_log)
+        local _, count = logs:gsub([[error:%[string "TMP"%]:4: attempt to call global 'type' %(a nil value%)]], "")
+
+        return count == 2
+      end, 5)
+    end)
     it("can inject a value from 'kong.ctx.shared'", function()
       local r = assert(client:send {
         method = "GET",