feat core/server/http: move graceful shutdown headers logic to a middleware

commit_hash:57e00cc1af404005d3e732ec8778c6fa3e539ed2

Author: lexeyo

.mapping.json

@@ -1970,6 +1970,8 @@
   "core/src/server/middlewares/decompression.hpp":"taxi/uservices/userver/core/src/server/middlewares/decompression.hpp",
   "core/src/server/middlewares/exceptions_handling.cpp":"taxi/uservices/userver/core/src/server/middlewares/exceptions_handling.cpp",
   "core/src/server/middlewares/exceptions_handling.hpp":"taxi/uservices/userver/core/src/server/middlewares/exceptions_handling.hpp",
+  "core/src/server/middlewares/graceful_shutdown_headers.cpp":"taxi/uservices/userver/core/src/server/middlewares/graceful_shutdown_headers.cpp",
+  "core/src/server/middlewares/graceful_shutdown_headers.hpp":"taxi/uservices/userver/core/src/server/middlewares/graceful_shutdown_headers.hpp",
   "core/src/server/middlewares/handler_adapter.cpp":"taxi/uservices/userver/core/src/server/middlewares/handler_adapter.cpp",
   "core/src/server/middlewares/handler_adapter.hpp":"taxi/uservices/userver/core/src/server/middlewares/handler_adapter.hpp",
   "core/src/server/middlewares/handler_metrics.cpp":"taxi/uservices/userver/core/src/server/middlewares/handler_metrics.cpp",

core/include/userver/server/middlewares/builtin.hpp

@@ -20,6 +20,7 @@ inline constexpr std::string_view kBaggage = "userver-baggage-middleware";
 inline constexpr std::string_view kAuth = "userver-auth-middleware";
 inline constexpr std::string_view kDecompression = "userver-decompression-middleware";
 inline constexpr std::string_view kExceptionsHandling = "userver-exceptions-handling-middleware";
+inline constexpr std::string_view kGracefulShutdownHeaders = "userver-graceful-shutdown-headers";
 
 }  // namespace server::middlewares::builtin
 

core/src/server/http/http_request_handler.cpp

@@ -19,7 +19,6 @@
 #include <userver/server/request/task_inherited_request.hpp>
 #include <userver/utils/assert.hpp>
 
-#include <dynamic_config/variables/GRACEFUL_SHUTDOWN_HEADERS.hpp>
 #include <dynamic_config/variables/USERVER_RPS_CCONTROL_CUSTOM_STATUS.hpp>
 
 USERVER_NAMESPACE_BEGIN
@@ -33,8 +32,7 @@ HttpRequestHandler::HttpRequestHandler(
     bool is_monitor,
     std::string server_name
 )
-    : components_state_(component_context),
-      is_monitor_(is_monitor),
+    : is_monitor_(is_monitor),
       server_name_(std::move(server_name)),
       rate_limit_(utils::TokenBucket::MakeUnbounded()),
       metrics_(component_context.FindComponent<components::StatisticsStorage>().GetMetricsStorage()),
@@ -81,15 +79,6 @@ engine::TaskWithResult<void> HttpRequestHandler::StartRequestTask(std::shared_pt
 ) const {
     auto& http_response = http_request->GetHttpResponse();
     http_response.SetHeader(USERVER_NAMESPACE::http::headers::kServer, server_name_);
-    if (components_state_.GetServiceLifetimeStage() == components::ServiceLifetimeStage::kGracefulShutdown) {
-        const auto config = config_source_.GetSnapshot();
-        auto config_var = config[::dynamic_config::GRACEFUL_SHUTDOWN_HEADERS];
-        if (config_var.enabled) {
-            for (const auto& [name, values] : config_var.headers.extra) {
-                http_response.SetHeader(name, fmt::to_string(fmt::join(values, ", ")));
-            }
-        }
-    }
     if (http_response.IsReady()) {
         // Request is broken somehow, user handler must not be called
         http_request->SetTaskCreateTime();

core/src/server/http/http_request_handler.hpp

@@ -4,7 +4,6 @@
 
 #include <server/http/request_handler_base.hpp>
 #include <userver/components/component_context.hpp>
-#include <userver/components/state.hpp>
 #include <userver/engine/mutex.hpp>
 #include <userver/engine/task/task_processor_fwd.hpp>
 #include <userver/engine/task/task_with_result.hpp>
@@ -54,7 +53,6 @@ class HttpRequestHandler final : public RequestHandlerBase {
 
     HandlerInfoIndex handler_info_index_;
 
-    const components::State components_state_;
     const bool is_monitor_;
     const std::string server_name_;
     NewRequestHook new_request_hook_;

core/src/server/middlewares/configuration.cpp

@@ -11,6 +11,7 @@
 #include <server/middlewares/deadline_propagation.hpp>
 #include <server/middlewares/decompression.hpp>
 #include <server/middlewares/exceptions_handling.hpp>
+#include <server/middlewares/graceful_shutdown_headers.hpp>
 #include <server/middlewares/handler_adapter.hpp>
 #include <server/middlewares/handler_metrics.hpp>
 #include <server/middlewares/rate_limit.hpp>
@@ -37,6 +38,7 @@ MiddlewaresList DefaultPipeline() {
 
         // Setting headers middlewares should be before terminating middlewares to set headers for errors
         std::string{builtin::kTracing},
+        std::string{builtin::kGracefulShutdownHeaders},
         std::string{builtin::kSetAcceptEncoding},
 
         // Should be self-explanatory
@@ -73,6 +75,7 @@ components::ComponentList DefaultMiddlewareComponents() {
         .Append<SetAcceptEncodingFactory>()
         .Append<ExceptionsHandlingFactory>()
         .Append<UnknownExceptionsHandlingFactory>()
+        .Append<GracefulShutdownHeadersFactory>()
         .Append<testsuite::ExceptionsHandlingMiddlewareFactory>();
 }
 

core/src/server/middlewares/graceful_shutdown_headers.cpp

@@ -0,0 +1,52 @@
+#include <server/middlewares/graceful_shutdown_headers.hpp>
+
+#include <dynamic_config/variables/GRACEFUL_SHUTDOWN_HEADERS.hpp>
+
+#include <server/request/internal_request_context.hpp>
+#include <userver/components/component_config.hpp>
+#include <userver/components/component_context.hpp>
+#include <userver/server/http/http_request.hpp>
+#include <userver/server/request/request_context.hpp>
+
+USERVER_NAMESPACE_BEGIN
+
+namespace server::middlewares {
+
+GracefulShutdownHeaders::GracefulShutdownHeaders(const handlers::HttpHandlerBase&, const components::State& state)
+    : HttpMiddlewareBase(),
+      state_(state)
+{}
+
+void GracefulShutdownHeaders::HandleRequest(http::HttpRequest& request, request::RequestContext& context) const {
+    if (state_.GetServiceLifetimeStage() == components::ServiceLifetimeStage::kGracefulShutdown) {
+        const auto config = context.GetInternalContext().GetConfigSnapshot();
+        auto graceful_shutdown_headers = config[::dynamic_config::GRACEFUL_SHUTDOWN_HEADERS];
+        if (graceful_shutdown_headers.enabled) {
+            auto& response = request.GetHttpResponse();
+            for (const auto& [name, values] : graceful_shutdown_headers.headers.extra) {
+                response.SetHeader(name, fmt::to_string(fmt::join(values, ", ")));
+            }
+        }
+    }
+
+    Next(request, context);
+}
+
+GracefulShutdownHeadersFactory::GracefulShutdownHeadersFactory(
+    const components::ComponentConfig& config,
+    const components::ComponentContext& context
+)
+    : HttpMiddlewareFactoryBase(config, context),
+      state_(context)
+{}
+
+std::unique_ptr<HttpMiddlewareBase> GracefulShutdownHeadersFactory::Create(
+    const handlers::HttpHandlerBase& handler,
+    yaml_config::YamlConfig
+) const {
+    return std::make_unique<GracefulShutdownHeaders>(handler, state_);
+}
+
+}  // namespace server::middlewares
+
+USERVER_NAMESPACE_END

core/src/server/middlewares/graceful_shutdown_headers.hpp

@@ -0,0 +1,44 @@
+#pragma once
+
+#include <userver/components/state.hpp>
+#include <userver/server/middlewares/builtin.hpp>
+#include <userver/server/middlewares/http_middleware_base.hpp>
+USERVER_NAMESPACE_BEGIN
+
+namespace server::middlewares {
+
+class GracefulShutdownHeaders final : public HttpMiddlewareBase {
+public:
+    explicit GracefulShutdownHeaders(const handlers::HttpHandlerBase&, const components::State& state);
+
+private:
+    void HandleRequest(http::HttpRequest& request, request::RequestContext& context) const override;
+
+    const components::State state_;
+};
+
+class GracefulShutdownHeadersFactory final : public HttpMiddlewareFactoryBase {
+public:
+    static constexpr std::string_view kName = builtin::kGracefulShutdownHeaders;
+
+    GracefulShutdownHeadersFactory(const components::ComponentConfig&, const components::ComponentContext& context);
+
+private:
+    std::unique_ptr<HttpMiddlewareBase> Create(
+        const handlers::HttpHandlerBase&,
+        yaml_config::YamlConfig middleware_config
+    ) const override;
+
+    const components::State state_;
+};
+
+}  // namespace server::middlewares
+
+template <>
+inline constexpr bool components::kHasValidate<server::middlewares::GracefulShutdownHeadersFactory> = true;
+
+template <>
+inline constexpr auto
+    components::kConfigFileMode<server::middlewares::GracefulShutdownHeadersFactory> = ConfigFileMode::kNotRequired;
+
+USERVER_NAMESPACE_END