client_factory_component.hpp

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#pragma once
 
/// @file userver/ugrpc/client/client_factory_component.hpp
/// @brief @copybrief ugrpc::client::ClientFactoryComponent
 
#include <userver/components/component_base.hpp>
#include <userver/middlewares/runner.hpp>
 
#include <userver/ugrpc/client/client_factory.hpp>
#include <userver/ugrpc/client/middlewares/base.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace ugrpc::client {
 
namespace impl {
 
/// @brief The interface for a `ClientFactoryComponent` component. So, `ClientFactoryComponent` runs with middlewares.
using MiddlewareRunnerComponentBase = USERVER_NAMESPACE::middlewares::RunnerComponentBase<MiddlewareBase, ClientInfo>;
 
}  // namespace impl
 
/// @ingroup userver_components
///
/// @brief Provides a ClientFactory in the component system
///
/// Multiple ClientFactoryComponent instances may be created if different
/// parameters are required for different clients.
///
/// Requires ugrpc::client::CommonComponent.
///
/// ## Authentication
/// Authentication is controlled by `auth-type` static config field.
/// Possible values:
/// - `insecure` (`InsecureChannelCredentials` - default)
/// - `ssl` (`SslCredentials`)
///
/// Default (system) authentication keys are used regardless of the chosen
/// auth-type.
///
/// ## Service config
/// As per https://github.com/grpc/grpc/blob/master/doc/service_config.md
/// service config should be distributed via the name resolution process.
/// We allow setting default service_config: pass desired JSON literal to `default-service-config` parameter
///
/// ## Dynamic config bootstrap
/// By default this component waits for @ref components::DynamicConfig to load the first successful dynamic config
/// update (via @ref components::DynamicConfig::GetSource() "GetSource()"), which may block component construction.
/// Set `use-constant-dynamic-configs: true` to instead use
/// @ref components::DynamicConfig::GetDefaultsAsConstantSource() "GetDefaultsAsConstantSource()" — a non-blocking,
/// constant @ref dynamic_config::Source built from @ref components::DynamicConfig's own fallback defaults. This is
/// useful e.g. for a gRPC client used to deliver dynamic configs to the service itself, where waiting for
/// @ref components::DynamicConfig would create a bootstrap cycle.
///
/// When `use-constant-dynamic-configs` is in effect, this component also skips
/// @ref ugrpc::client::CommonComponent's shared default `retry-limiter` (as set by `grpc-client-common`'s
/// `retry-limiter`/`retry-limiter-enabled` options), since that default implementation may itself depend on
/// @ref components::DynamicConfig (e.g. the standard `statistics-retry-limiter` component), which would reintroduce
/// the same bootstrap dependency. An explicit `retry-limiter` specified directly in this component's own static
/// config is still always honored, regardless of `use-constant-dynamic-configs`; set it to `none` to force no
/// retry-limiter at all for this factory, even if a `grpc-client-common` default is configured.
///
/// ## Example: a "light" client factory used to deliver dynamic configs to the service itself
/// @snippet grpc/functional_tests/light_client/static_config.yaml Sample light grpc client factory config
///
/// ## Static options of ugrpc::client::ClientFactoryComponent :
/// @include{doc} scripts/docs/en/components_schema/grpc/src/ugrpc/client/client_factory_component.md
///
/// Options inherited from @ref middlewares::RunnerComponentBase :
/// @include{doc} scripts/docs/en/components_schema/core/src/middlewares/runner_component_base.md
///
/// Options inherited from @ref components::ComponentBase :
/// @include{doc} scripts/docs/en/components_schema/core/src/components/impl/component_base.md
///
/// The default component name for static config is `"grpc-client-factory"`.
///
/// @see https://grpc.github.io/grpc/core/group__grpc__arg__keys.html
class ClientFactoryComponent final : public impl::MiddlewareRunnerComponentBase {
public:
    /// @ingroup userver_component_names
    /// @brief The default name of ugrpc::client::middlewares::log::Component
    static constexpr std::string_view kName = "grpc-client-factory";
 
    ClientFactoryComponent(const components::ComponentConfig& config, const components::ComponentContext& context);
 
    ClientFactory& GetFactory();
 
    static yaml_config::Schema GetStaticConfigSchema();
 
private:
    std::optional<ClientFactory> factory_;
};
 
}  // namespace ugrpc::client
 
template <>
inline constexpr bool components::kHasValidate<ugrpc::client::ClientFactoryComponent> = true;
 
USERVER_NAMESPACE_END