envoyproxy · ggreenway · Jun 22, 2021 · Jun 18, 2021 · Jun 18, 2021 · Jun 18, 2021
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
@@ -83,6 +83,7 @@ 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 resolver: added *DnsResolverOptions* protobuf message to reconcile all of the DNS lookup option flags. By setting the configuration option :ref:`use_tcp_for_dns_lookups <envoy_v3_api_field_config.core.v3.DnsResolverOptions.use_tcp_for_dns_lookups>` as true we can make the underlying dns resolver library to make only TCP queries to the DNS servers and by setting the configuration option :ref:`no_default_search_domain <envoy_v3_api_field_config.core.v3.DnsResolverOptions.no_default_search_domain>` as true the DNS resolver library will not use the default search domains.

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"}}),