feat(tracing): route/service scoping

implement KAG-244

CHANGELOG.md

@@ -96,6 +96,8 @@
   parameter that allows the selection of the IMDS protocol version.
   Defaults to `v1`, can be set to `v2` to enable IMDSv2.
   [#9962](https://github.com/Kong/kong/pull/9962)
+- **OpenTelemetry**: Support Service and Router scoping.
+  [#10096](https://github.com/Kong/kong/pull/10096)
 
 ### Fixes
 

kong/pdk/tracing.lua

@@ -425,7 +425,7 @@ local function new_tracer(name, options)
   -- @tparam table options TODO(mayo)
   -- @treturn table span
   function self.start_span(...)
-    if not base.get_request() then
+    if (not base.get_request()) or ngx.ctx.stoping_tracing then
       return noop_span
     end
 
@@ -488,8 +488,124 @@ setmetatable(noop_tracer, {
   __newindex = NOOP,
 })
 
+local function terminate_tracers()
+  -- stop further tracing
+  ngx.ctx.stoping_tracing = true
+
+  local spans = ngx.ctx.KONG_SPANS
+  if type(spans) ~= "table" then
+    return
+  end
+
+  -- stop existing spans
+  for _, span in ipairs(spans) do
+    if type(span) == "table" then
+      span.should_sample = false
+    end
+  end
+end
+
+local register_tracer_plugin, is_tracers_enabled_at
+do
+  local GLOBAL_QUERY_OPTS = { workspace = ngx.null, show_ws_id = true }
+
+  local tracers = {}
+  local tracers_n = 0
+
+
+  local function get_cache_key(name)
+    return "tracers:is_enabled_at:" .. name
+  end
+
+  -- we cannot decide consumer before access phase, so tracer plugins must
+  -- be defined no_consumer
+  local function get_tracer_enabled_path(name)
+    local enabled_tbl = {}
+    for plugin, err in kong.db.plugins:each(nil, GLOBAL_QUERY_OPTS) do
+      if err then
+        kong.log.crit("could not obtain list of plugins: ", err)
+        goto continue
+      end
+
+      if plugin.name == name and plugin.enabled then
+        if plugin.route and not plugin.service then
+          enabled_tbl[plugin.route.id] = true
+        end
+
+        if plugin.service and not plugin.route then
+          enabled_tbl[plugin.service.id] = true
+        end
+
+        if plugin.route and plugin.service then
+          enabled_tbl[plugin.route.id .. ":" .. plugin.service.id] = true
+        end
+
+        if not plugin.route and not plugin.servicer then
+          enabled_tbl.global = true
+        end
+      end
+      ::continue::
+    end
+
+    return enabled_tbl
+  end
+
+  local function is_tracer_enabled_at(name, route_id, service_id)
+    local enabled_tbl, err = kong.cache:get(get_cache_key(name), nil, get_tracer_enabled_path, name)
+
+    if not enabled_tbl then
+      return false, err
+    end
+
+    -- any of them enabled, we should do the tracing
+    return enabled_tbl.global or enabled_tbl[route_id] or enabled_tbl[service_id] or enabled_tbl[route_id .. ":" .. service_id]
+  end
+
+  local function invalidate_cache_event(name)
+    local worker_events = kong.worker_events
+    local cache_key = get_cache_key(name)
+    -- invalidations
+    if kong.configuration.database == "off" then
+      worker_events.register(function()
+        kong.cache:invalidate(cache_key)
+      end, "declarative", "reconfigure")
+
+    else
+      worker_events.register(function(data)
+        if data.entity.name == name then
+          kong.cache:invalidate(cache_key)
+        end
+      end, "crud", "plugins")
+    end
+  end
+
+  function register_tracer_plugin(name)
+    invalidate_cache_event(name)
+    tracers_n = tracers_n + 1
+    tracers[tracers_n] = name
+  end
+
+  function is_tracers_enabled_at(router_id, service_id)
+    for i = 1, tracers_n do
+      local enabled, err = is_tracer_enabled_at(tracers[i], router_id, service_id)
+
+      if err then
+        kong.log.debug("failed to check if tracer is enabled: ", err)
+      end
+
+      if enabled then
+        return true
+      end
+    end
+    return false
+  end
+end
+
 return {
   new = function()
     return global_tracer
   end,
+  register_tracer_plugin = register_tracer_plugin,
+  is_tracers_enabled_at = is_tracers_enabled_at,
+  terminate_tracers = terminate_tracers,
 }

kong/plugins/opentelemetry/handler.lua

@@ -3,6 +3,7 @@ local http = require "resty.http"
 local clone = require "table.clone"
 local otlp = require "kong.plugins.opentelemetry.otlp"
 local propagation = require "kong.tracing.propagation"
+local register_tracer_plugin = require("kong.pdk.tracing").register_tracer_plugin
 
 local pairs = pairs
 
@@ -113,7 +114,12 @@ local function process_span(span, queue)
   queue:add(pb_span)
 end
 
-function OpenTelemetryHandler:rewrite()
+function OpenTelemetryHandler:init()
+  register_tracer_plugin("opentelemetry")
+end
+
+-- TODO: unify handling of propagation with other tracers like zipkin
+function OpenTelemetryHandler:access()
   local headers = ngx_get_headers()
   local root_span = ngx.ctx.KONG_SPANS and ngx.ctx.KONG_SPANS[1]
 

kong/plugins/opentelemetry/schema.lua

@@ -30,10 +30,8 @@ local resource_attributes = Schema.define {
 return {
   name = "opentelemetry",
   fields = {
-    -- global plugin only
+    -- tracer pluign does not scope on consumers
     { consumer = typedefs.no_consumer },
-    { service = typedefs.no_service },
-    { route = typedefs.no_route },
     { protocols = typedefs.protocols_http }, -- TODO: support stream mode
     { config = {
       type = "record",

kong/runloop/handler.lua

@@ -13,6 +13,7 @@ local lrucache     = require "resty.lrucache"
 local marshall     = require "kong.cache.marshall"
 
 
+local tracing         = require "kong.pdk.tracing"
 local PluginsIterator = require "kong.runloop.plugins_iterator"
 local instrumentation = require "kong.tracing.instrumentation"
 
@@ -44,6 +45,8 @@ local clear_header      = ngx.req.clear_header
 local http_version      = ngx.req.http_version
 local escape            = require("kong.tools.uri").escape
 
+local is_tracers_enabled_at = tracing.is_tracers_enabled_at
+local terminate_tracers     = tracing.terminate_tracers
 
 local is_http_module   = subsystem == "http"
 local is_stream_module = subsystem == "stream"
@@ -1116,14 +1119,28 @@ return {
       local match_t = router:exec(ctx)
       if not match_t then
         -- tracing
+
+        -- we do not trace 404 requests
         if span then
-          span:set_status(2)
+          span.should_sample = false
           span:finish()
+          terminate_tracers()
         end
 
         return kong.response.exit(404, { message = "no Route matched with those values" })
       end
 
+      -- is tracing enabled?
+      local route_id = match_t.route and match_t.route.id
+      local service_id = match_t.service and match_t.service.id
+      if not is_tracers_enabled_at(route_id, service_id) then
+        if span then
+          span.should_sample = false
+        end
+
+        terminate_tracers()
+      end
+
       -- ends tracing span
       if span then
         span:finish()

spec/03-plugins/37-opentelemetry/04-exporter_spec.lua

@@ -52,17 +52,22 @@ for _, strategy in helpers.each_strategy() do
         port = helpers.mock_upstream_port,
       })
 
-      bp.routes:insert({ service = http_srv,
-                         protocols = { "http" },
-                         paths = { "/" }})
+      local route = assert(bp.routes:insert({ service = http_srv,
+                                              protocols = { "http" },
+                                              paths = { "/" }}))
 
-      bp.plugins:insert({
+      assert(bp.routes:insert({ service = http_srv,
+                                protocols = { "http" },
+                                paths = { "/no_plugin" }}))
+
+      assert(bp.plugins:insert({
         name = "opentelemetry",
+        route = route,
         config = table_merge({
           endpoint = "http://127.0.0.1:" .. HTTP_SERVER_PORT,
           batch_flush_delay = 0, -- report immediately
         }, config)
-      })
+      }))
 
       assert(helpers.start_kong({
         proxy_listen = "0.0.0.0:" .. PROXY_PORT,
@@ -140,6 +145,52 @@ for _, strategy in helpers.each_strategy() do
       end)
     end)
 
+    describe("#scoping", function ()
+      lazy_setup(function()
+        bp, _ = assert(helpers.get_db_utils(strategy, {
+          "services",
+          "routes",
+          "plugins",
+        }, { "opentelemetry" }))
+
+        setup_instrumentations("all", {
+          headers = {
+            ["X-Access-Token"] = "token",
+          },
+        })
+      end)
+
+      lazy_teardown(function()
+        helpers.stop_kong()
+        helpers.kill_http_server(HTTP_SERVER_PORT)
+      end)
+
+      it("works", function ()
+        local thread = helpers.http_server(HTTP_SERVER_PORT, { timeout = 10 })
+        local cli = helpers.proxy_client(7000, PROXY_PORT)
+        local r = assert(cli:send {
+          method  = "GET",
+          path    = "/no_plugin",
+        })
+        assert.res_status(200, r)
+        r = assert(cli:send {
+          method  = "GET",
+          path    = "/no_exist",
+        })
+        assert.res_status(404, r)
+
+        -- close client connection
+        cli:close()
+
+        local ok, err = thread:join()
+
+        ngx.sleep(1000)
+        -- we should have no telemetry reported
+        assert.is_falsy(ok)
+        assert.same(err, "timeout")
+      end)
+    end)
+
     describe("overwrite resource attributes #http", function ()
       lazy_setup(function()
         bp, _ = assert(helpers.get_db_utils(strategy, {
@@ -284,7 +335,6 @@ for _, strategy in helpers.each_strategy() do
           local body = fd:read("*a")
           pb_set = ngx_re.split(body, "\n")
 
-          print("pb set length: ", #pb_set)
           local count = 0
           for _, pb_data in ipairs(pb_set) do
             local decoded = assert(pb.decode("opentelemetry.proto.collector.trace.v1.ExportTraceServiceRequest", ngx.decode_base64(pb_data)))