Returning JSON responses for common upstream server errors

Yatufo · Feb 9, 2016 · 676d2ce · 676d2ce
1 parent b708576
commit 676d2ce
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Showing 3 changed files with 59 additions and 6 deletions.
diff --git a/kong-0.6.1-0.rockspec b/kong-0.6.1-0.rockspec
@@ -89,6 +89,7 @@ build = {
     ["kong.core.reports"] = "kong/core/reports.lua",
     ["kong.core.cluster"] = "kong/core/cluster.lua",
     ["kong.core.events"] = "kong/core/events.lua",
+    ["kong.core.error_handlers"] = "kong/core/error_handlers.lua",
 
     ["kong.dao.cassandra.schema.migrations"] = "kong/dao/cassandra/schema/migrations.lua",
     ["kong.dao.error"] = "kong/dao/error.lua",

diff --git a/kong.yml b/kong.yml
@@ -280,13 +280,13 @@ nginx: |
         return 200 'User-agent: *\nDisallow: /';
       }
 
-      error_page 500 /500.html;
-      location = /500.html {
+      error_page 500 502 503 504 /50x;
+
+      location = /50x {
         internal;
-        content_by_lua '
-          local responses = require "kong.tools.responses"
-          responses.send_HTTP_INTERNAL_SERVER_ERROR("An unexpected error occurred")
-        ';
+        content_by_lua_block {
+          require("kong.core.error_handlers")(ngx)
+        }
       }
     }
 

diff --git a/kong/core/error_handlers.lua b/kong/core/error_handlers.lua
@@ -0,0 +1,52 @@
+local constants = require "kong.constants"
+local find = string.find
+local format = string.format
+
+local TYPE_PLAIN = "text/plain"
+local TYPE_JSON = "application/json"
+local TYPE_XML = "application/xml"
+local TYPE_HTML = "text/html"
+
+local text_template = "%s"
+local json_template = '{"message":"%s"}'
+local xml_template = '<?xml version="1.0" encoding="UTF-8"?>\n<error><message>%s</message></error>'
+local html_template = '<html><head><title>Kong Error</title></head><body><h1>Kong Error</h1><p>%s.</p></body></html>'
+
+local BODIES = {
+  s500 = "An unexpected error occurred",
+  s502 = "An invalid response was received from the upstream server",
+  s503 = "The upstream server is currently unavailable",
+  s504 = "The upstream server is timing out",
+  default = "The upstream server responded with %d"
+}
+
+local SERVER_HEADER = constants.NAME.."/"..constants.VERSION
+
+return function(ngx)
+  local accept_header = ngx.req.get_headers()["accept"]
+  local template, message, content_type
+
+  if accept_header == nil then
+    template = text_template
+    content_type = TYPE_PLAIN
+  elseif find(accept_header, TYPE_HTML, nil, true) then
+    template = html_template
+    content_type = TYPE_HTML
+  elseif find(accept_header, TYPE_JSON, nil, true) then
+    template = json_template
+    content_type = TYPE_JSON
+  elseif find(accept_header, TYPE_XML, nil, true) then
+    template = xml_template
+    content_type = TYPE_XML
+  else
+    template = text_template
+    content_type = TYPE_PLAIN
+  end
+
+  local status = ngx.status
+  message = BODIES["s"..status] and BODIES["s"..status] or format(BODIES.default, status)
+
+  ngx.header["Server"] = SERVER_HEADER
+  ngx.header["Content-Type"] = content_type
+  ngx.say(format(template, message))
+end