fix(clustering): ensure data plane config hash is never nil

changelog/unreleased/kong/clustering-empty-data-plane-hash-fix.yml

@@ -0,0 +1,3 @@
+message: Fix a bug causing data-plane status updates to fail when an empty PING frame is received from a data-plane
+type: bugfix
+scope: Clustering

kong/clustering/control_plane.lua

@@ -234,7 +234,9 @@ function _M:handle_cp_websocket()
     local ok
     ok, err = kong.db.clustering_data_planes:upsert({ id = dp_id, }, {
       last_seen = last_seen,
-      config_hash = config_hash ~= "" and config_hash or nil,
+      config_hash = config_hash ~= ""
+                and config_hash
+                 or DECLARATIVE_EMPTY_CONFIG_HASH,
       hostname = dp_hostname,
       ip = dp_ip,
       version = dp_version,
@@ -341,6 +343,10 @@ function _M:handle_cp_websocket()
 
       if not data then
         return nil, "did not receive ping frame from data plane"
+
+      elseif #data ~= 32 then
+        return nil, "received a ping frame from the data plane with an invalid"
+                 .. " hash: '" .. tostring(data) .. "'"
       end
 
       -- dps only send pings

kong/clustering/data_plane.lua

@@ -91,7 +91,7 @@ local function send_ping(c, log_suffix)
 
   local hash = declarative.get_current_hash()
 
-  if hash == true then
+  if hash == "" or type(hash) ~= "string" then
     hash = DECLARATIVE_EMPTY_CONFIG_HASH
   end
 

spec/02-integration/20-wasm/06-clustering_spec.lua

@@ -11,19 +11,8 @@ local FILTER_SRC = "spec/fixtures/proxy_wasm_filters/build/response_transformer.
 local json = cjson.encode
 local file = helpers.file
 
-local function get_node_id(prefix)
-  local data = helpers.wait_for_file_contents(prefix .. "/kong.id")
-  data = data:gsub("%s*(.-)%s*", "%1")
-  assert(utils.is_valid_uuid(data), "invalid kong node ID found in " .. prefix)
-  return data
-end
-
-
-local function expect_status(prefix, exp)
-  local id = get_node_id(prefix)
-  local msg = "waiting for clustering sync status to equal"
-              .. " '" .. exp .. "' for data plane"
 
+local function expect_status(id, exp)
   assert
     .eventually(function()
       local cp_client = helpers.admin_client()
@@ -69,7 +58,8 @@ local function expect_status(prefix, exp)
 
       return true
     end)
-    .is_truthy(msg)
+    .is_truthy("waiting for clustering sync status to equal "
+           .. "'filter_set_incompatible' for data plane")
 end
 
 local function new_wasm_filter_directory()
@@ -89,6 +79,9 @@ describe("#wasm - hybrid mode #postgres", function()
   local dp_prefix = "dp"
 
   lazy_setup(function()
+    helpers.clean_prefix(cp_prefix)
+    helpers.clean_prefix(dp_prefix)
+
     local _, db = helpers.get_db_utils("postgres", {
       "services",
       "routes",
@@ -129,9 +122,11 @@ describe("#wasm - hybrid mode #postgres", function()
   describe("[happy path]", function()
     local client
     local dp_filter_path
+    local node_id
 
     lazy_setup(function()
       dp_filter_path = new_wasm_filter_directory()
+      node_id = utils.uuid()
 
       assert(helpers.start_kong({
         role                  = "data_plane",
@@ -144,6 +139,7 @@ describe("#wasm - hybrid mode #postgres", function()
         nginx_conf            = "spec/fixtures/custom_nginx.template",
         wasm                  = true,
         wasm_filters_path     = dp_filter_path,
+        node_id               = node_id,
       }))
 
       client = helpers.proxy_client()
@@ -271,13 +267,16 @@ describe("#wasm - hybrid mode #postgres", function()
         end)
         .is_truthy("wasm filter has been removed from the data plane")
 
-      expect_status(dp_prefix, STATUS.NORMAL)
+      expect_status(node_id, STATUS.NORMAL)
     end)
   end)
 
   describe("data planes with wasm disabled", function()
+    local node_id
+
     lazy_setup(function()
       helpers.clean_logfile(cp_errlog)
+      node_id = utils.uuid()
 
       assert(helpers.start_kong({
         role                  = "data_plane",
@@ -289,6 +288,7 @@ describe("#wasm - hybrid mode #postgres", function()
         admin_listen          = "off",
         nginx_conf            = "spec/fixtures/custom_nginx.template",
         wasm                  = "off",
+        node_id               = node_id,
       }))
     end)
 
@@ -302,16 +302,18 @@ describe("#wasm - hybrid mode #postgres", function()
         [[unable to send updated configuration to data plane: data plane is missing one or more wasm filters]],
         true, 5)
 
-      expect_status(dp_prefix, STATUS.FILTER_SET_INCOMPATIBLE)
+      expect_status(node_id, STATUS.FILTER_SET_INCOMPATIBLE)
     end)
   end)
 
   describe("data planes missing one or more wasm filter", function()
     local tmp_dir
+    local node_id
 
     lazy_setup(function()
       helpers.clean_logfile(cp_errlog)
       tmp_dir = helpers.make_temp_dir()
+      node_id = utils.uuid()
 
       assert(helpers.start_kong({
         role                  = "data_plane",
@@ -324,6 +326,7 @@ describe("#wasm - hybrid mode #postgres", function()
         nginx_conf            = "spec/fixtures/custom_nginx.template",
         wasm                  = true,
         wasm_filters_path     = tmp_dir,
+        node_id               = node_id,
       }))
     end)
 
@@ -338,7 +341,7 @@ describe("#wasm - hybrid mode #postgres", function()
         [[unable to send updated configuration to data plane: data plane is missing one or more wasm filters]],
         true, 5)
 
-      expect_status(dp_prefix, STATUS.FILTER_SET_INCOMPATIBLE)
+      expect_status(node_id, STATUS.FILTER_SET_INCOMPATIBLE)
     end)
   end)
 end)