feat(proxy): make error responses content type compliant with request header values

CHANGELOG.md

@@ -69,6 +69,12 @@
 
 ## Unreleased
 
+### Additions
+
+#### Core
+
+- Make runloop and init error response content types compliant with Accept header value
+  [#10366](https://github.com/Kong/kong/pull/10366)
 ### Dependencies
 
 - Bumped lua-resty-session from 4.0.2 to 4.0.3

kong/init.lua

@@ -433,9 +433,9 @@ local function flush_delayed_response(ctx)
     return -- avoid tail call
   end
 
-  kong.response.exit(ctx.delayed_response.status_code,
-                     ctx.delayed_response.content,
-                     ctx.delayed_response.headers)
+  local dr = ctx.delayed_response
+  local message = dr.content and dr.content.message or dr.content
+  kong.response.error(dr.status_code, message, dr.headers)
 end
 
 
@@ -1005,7 +1005,7 @@ function Kong.access()
 
     ctx.buffered_proxying = nil
 
-    return kong.response.exit(503, { message = "no Service found with those values"})
+    return kong.response.error(503, "no Service found with those values")
   end
 
   runloop.access.after(ctx)

kong/runloop/handler.lua

@@ -1079,8 +1079,7 @@ return {
     after = function(ctx)
       local ok, err, errcode = balancer_execute(ctx)
       if not ok then
-        local body = utils.get_default_exit_body(errcode, err)
-        return kong.response.exit(errcode, body)
+        return kong.response.error(errcode, err)
       end
     end
   },
@@ -1118,7 +1117,7 @@ return {
           span:finish()
         end
 
-        return kong.response.exit(404, { message = "no Route matched with those values" })
+        return kong.response.error(404, "no Route matched with those values")
       end
 
       -- ends tracing span
@@ -1185,7 +1184,7 @@ return {
         local redirect_status_code = route.https_redirect_status_code or 426
 
         if redirect_status_code == 426 then
-          return kong.response.exit(426, { message = "Please use HTTPS protocol" }, {
+          return kong.response.error(426, "Please use HTTPS protocol", {
             ["Connection"] = "Upgrade",
             ["Upgrade"]    = "TLS/1.2, HTTP/1.1",
           })
@@ -1209,15 +1208,15 @@ return {
         if content_type and sub(content_type, 1, #"application/grpc") == "application/grpc" then
           if protocol_version ~= 2 then
             -- mismatch: non-http/2 request matched grpc route
-            return kong.response.exit(426, { message = "Please use HTTP2 protocol" }, {
+            return kong.response.error(426, "Please use HTTP2 protocol", {
               ["connection"] = "Upgrade",
               ["upgrade"]    = "HTTP/2",
             })
           end
 
         else
           -- mismatch: non-grpc request matched grpc route
-          return kong.response.exit(415, { message = "Non-gRPC request matched gRPC route" })
+          return kong.response.error(415, "Non-gRPC request matched gRPC route")
         end
 
         if not protocols.grpc and forwarded_proto ~= "https" then
@@ -1339,8 +1338,7 @@ return {
 
       local ok, err, errcode = balancer_execute(ctx)
       if not ok then
-        local body = utils.get_default_exit_body(errcode, err)
-        return kong.response.exit(errcode, body)
+        return kong.response.error(errcode, err)
       end
 
       local ok, err = balancer.set_host_header(balancer_data, upstream_scheme, upstream_host)

spec/01-unit/16-runloop_handler_spec.lua

@@ -29,7 +29,7 @@ local function setup_it_block()
         warn = function() end,
       },
       response = {
-        exit = function() end,
+        error = function() end,
       },
       worker_events = {
         register = function() end,

spec/02-integration/05-proxy/29-collect-plugin-errors_spec.lua

@@ -0,0 +1,68 @@
+local helpers = require "spec.helpers"
+local cjson   = require "cjson"
+
+for _, strategy in helpers.each_strategy() do
+  describe("Collect plugin errors [#" .. strategy .. "]", function()
+    local client
+
+    lazy_setup(function()
+      local bp = helpers.get_db_utils(strategy, {
+        "routes",
+        "services",
+        "plugins",
+      },{
+        "logger"
+      })
+
+      local service = assert(bp.services:insert {
+        url = helpers.mock_upstream_url
+      })
+
+      local route = assert(bp.routes:insert {
+        service = service,
+        hosts = { "error.test" }
+      })
+
+      assert(bp.plugins:insert {
+        name = "error-generator",
+        route = { id = route.id },
+        config = {
+          access = true,
+        },
+      })
+      assert(bp.plugins:insert {
+        name = "logger",
+        route = { id = route.id },
+      })
+
+      assert(helpers.start_kong({
+        database   = strategy,
+        plugins    = "bundled, error-generator, logger",
+        nginx_conf = "spec/fixtures/custom_nginx.template",
+      }))
+      client = helpers.proxy_client()
+    end)
+
+    lazy_teardown(function()
+      if client then
+        client:close()
+      end
+      helpers.stop_kong()
+    end)
+
+    it("delays the error response", function()
+      local res = assert(client:get("/get", {
+        headers = {
+          Host = "error.test",
+        }
+      }))
+      local body = assert.res_status(500, res)
+      local json = cjson.decode(body)
+      assert.same({ message = "An unexpected error occurred" }, json)
+      -- the other plugin's phases were executed:
+      assert.logfile().has.line("header_filter phase", true)
+      assert.logfile().has.line("body_filter phase", true)
+      assert.logfile().has.line("log phase", true)
+    end)
+  end)
+end

spec/03-plugins/33-serverless-functions/02-access_spec.lua

@@ -292,7 +292,8 @@ for _, plugin_name in ipairs({ "pre-function", "post-function" }) do
             }
           })
           local body = assert.res_status(500, res)
-          assert.same('{"message":"An unexpected error occurred"}', body)
+          local json = cjson.decode(body)
+          assert.same({ message = "An unexpected error occurred" }, json)
         end)
       end)