rds: add config reload time stat for rds (#17033)

Signed-off-by: Rama Chavali <rama.rao@salesforce.com>
envoyproxy · Jun 22, 2021 · 305ea53 · 305ea53
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Showing 8 changed files with 15 additions and 4 deletions.
diff --git a/docs/root/configuration/overview/mgmt_server.rst b/docs/root/configuration/overview/mgmt_server.rst
@@ -53,6 +53,7 @@ The following statistics are generated for all subscriptions.
  :widths: 1, 1, 2
 
  config_reload, Counter, Total API fetches that resulted in a config reload due to a different config
+ config_reload_time_ms, Gauge, Timestamp of the last config reload as milliseconds since the epoch
  init_fetch_timeout, Counter, Total :ref:`initial fetch timeouts <envoy_v3_api_field_config.core.v3.ConfigSource.initial_fetch_timeout>`
  update_attempt, Counter, Total API fetches attempted
  update_success, Counter, Total API fetches completed successfully

diff --git a/docs/root/version_history/current.rst b/docs/root/version_history/current.rst
@@ -84,6 +84,7 @@ New Features
 * bootstrap: added :ref:`dns_resolution_config <envoy_v3_api_field_config.bootstrap.v3.Bootstrap.dns_resolution_config>` to aggregate all of the DNS resolver configuration in a single message. By setting one such configuration option ``no_default_search_domain`` as true the DNS resolver will not use the default search domains. And by setting the configuration ``resolvers`` we can specify the external DNS servers to be used for external DNS query.
 * cluster: added :ref:`dns_resolution_config <envoy_v3_api_field_config.cluster.v3.Cluster.dns_resolution_config>` to aggregate all of the DNS resolver configuration in a single message. By setting one such configuration option ``no_default_search_domain`` as true the DNS resolver will not use the default search domains.
 * composite filter: can now be used with filters that also add an access logger, such as the WASM filter.
+* config: added stat :ref:`config_reload_time_ms <subscription_statistics>`.
 * connection_limit: added new :ref:`Network connection limit filter <config_network_filters_connection_limit>`.
 * crash support: restore crash context when continuing to processing requests or responses as a result of an asynchronous callback that invokes a filter directly. This is unlike the call stacks that go through the various network layers, to eventually reach the filter. For a concrete example see: ``Envoy::Extensions::HttpFilters::Cache::CacheFilter::getHeaders`` which posts a callback on the dispatcher that will invoke the filter directly.
 * dns cache: added :ref:`preresolve_hostnames <envoy_v3_api_field_extensions.common.dynamic_forward_proxy.v3.DnsCacheConfig.preresolve_hostnames>` option to the DNS cache config. This option allows hostnames to be preresolved into the cache upon cache creation. This might provide performance improvement, in the form of cache hits, for hostnames that are going to be resolved during steady state and are known at config load time.

diff --git a/source/common/router/rds_impl.cc b/source/common/router/rds_impl.cc
@@ -88,7 +88,8 @@ RdsRouteConfigSubscription::RdsRouteConfigSubscription(
           fmt::format("RdsRouteConfigSubscription local-init-target {}", route_config_name_),
           [this]() { subscription_->start({route_config_name_}); }),
       local_init_manager_(fmt::format("RDS local-init-manager {}", route_config_name_)),
-      stat_prefix_(stat_prefix), stats_({ALL_RDS_STATS(POOL_COUNTER(*scope_))}),
+      stat_prefix_(stat_prefix),
+      stats_({ALL_RDS_STATS(POOL_COUNTER(*scope_), POOL_GAUGE(*scope_))}),
       route_config_provider_manager_(route_config_provider_manager),
       manager_identifier_(manager_identifier), optional_http_filters_(optional_http_filters) {
   const auto resource_name = getResourceName();
@@ -131,6 +132,7 @@ void RdsRouteConfigSubscription::onConfigUpdate(
   std::unique_ptr<Cleanup> resume_rds;
   if (config_update_info_->onRdsUpdate(route_config, version_info)) {
     stats_.config_reload_.inc();
+    stats_.config_reload_time_ms_.set(DateUtil::nowToMilliseconds(factory_context_.timeSource()));
     if (config_update_info_->protobufConfiguration().has_vhds() &&
         config_update_info_->vhdsConfigurationChanged()) {
       ENVOY_LOG(

diff --git a/source/common/router/rds_impl.h b/source/common/router/rds_impl.h
@@ -97,15 +97,16 @@ class StaticRouteConfigProviderImpl : public RouteConfigProvider {
 /**
  * All RDS stats. @see stats_macros.h
  */
-#define ALL_RDS_STATS(COUNTER)                                                                     \
+#define ALL_RDS_STATS(COUNTER, GAUGE)                                                              \
   COUNTER(config_reload)                                                                           \
-  COUNTER(update_empty)
+  COUNTER(update_empty)                                                                            \
+  GAUGE(config_reload_time_ms, NeverImport)
 
 /**
  * Struct definition for all RDS stats. @see stats_macros.h
  */
 struct RdsStats {
-  ALL_RDS_STATS(GENERATE_COUNTER_STRUCT)
+  ALL_RDS_STATS(GENERATE_COUNTER_STRUCT, GENERATE_GAUGE_STRUCT)
 };
 
 class RdsRouteConfigProviderImpl;

diff --git a/source/common/router/scoped_rds.cc b/source/common/router/scoped_rds.cc
@@ -393,6 +393,7 @@ void ScopedRdsConfigSubscription::onConfigUpdate(
   }
   stats_.all_scopes_.set(scoped_route_map_.size());
   stats_.config_reload_.inc();
+  stats_.config_reload_time_ms_.set(DateUtil::nowToMilliseconds(factory_context_.timeSource()));
 }
 
 void ScopedRdsConfigSubscription::onRdsConfigUpdate(const std::string& scope_name,

diff --git a/source/common/router/scoped_rds.h b/source/common/router/scoped_rds.h
@@ -86,6 +86,7 @@ class InlineScopedRoutesConfigProvider : public Envoy::Config::ImmutableConfigPr
   COUNTER(config_reload)                                                                           \
   COUNTER(update_empty)                                                                            \
   GAUGE(all_scopes, Accumulate)                                                                    \
+  GAUGE(config_reload_time_ms, NeverImport)                                                        \
   GAUGE(on_demand_scopes, Accumulate)                                                              \
   GAUGE(active_scopes, Accumulate)
 

diff --git a/test/common/router/rds_impl_test.cc b/test/common/router/rds_impl_test.cc
@@ -290,6 +290,7 @@ TEST_F(RdsImplTest, Basic) {
   // Old config use count should be 1 now.
   EXPECT_EQ(1, config.use_count());
   EXPECT_EQ(2UL, scope_.counter("foo.rds.foo_route_config.config_reload").value());
+  EXPECT_TRUE(scope_.findGaugeByString("foo.rds.foo_route_config.config_reload_time_ms"));
 }
 
 // validate there will be exception throw when unknown factory found for per virtualhost typed

diff --git a/test/common/router/scoped_rds_test.cc b/test/common/router/scoped_rds_test.cc
@@ -384,6 +384,9 @@ route_configuration_name: foo_routes
   EXPECT_EQ(2UL,
             server_factory_context_.scope_.counter("foo.scoped_rds.foo_scoped_routes.config_reload")
                 .value());
+  EXPECT_TRUE(server_factory_context_.scope_.findGaugeByString(
+      "foo.scoped_rds.foo_scoped_routes.config_reload_time_ms"));
+
   // now scope key "x-bar-key" points to nowhere.
   EXPECT_THAT(getScopedRdsProvider()->config<ScopedConfigImpl>()->getRouteConfig(
                   TestRequestHeaderMapImpl{{"Addr", "x-foo-key;x-bar-key"}}),