components::DynamicConfig Class Reference

#include <userver/dynamic_config/storage/component.hpp>

Detailed Description

Component that stores the dynamic config.

Note that the service with updates-enabled: true and without configs cache requires successful update to start. See dynamic_config_fallback for details and explanation.

Behavior on missing configs

If a config variable is entirely missing the fetched config, the value from dynamic_config_fallback.json is used (see fallback-path static config option).

Behavior on config parsing failure

If a config variable from the fetched config fails to be parsed (the parser fails with an exception), then the whole config update fails. It means that:

• If the service is just starting, it will shut down
• If the service is already running, the config updates will stop until the config in the config service changes to a valid one. You can monitor this situation using the metric at path cache.any.time.time-from-last-successful-start-ms

Static options

Name	Description	Default value
updates-enabled	should be set to 'true' if there is an updater component	false
defaults	overrides the defaults from dynamic_config::Key definitions in code	{}
fallback-path	a path to the fallback config	defaults are taken from dynamic_config::Key definitions
fs-cache-path	path to the file to read and dump a config cache; set to empty string to disable reading and dumping configs to FS	cache is disabled
fs-task-processor	name of the task processor to run the blocking file write operations	required if fs-cache-path is present

Static configuration example:

# yaml
    dynamic-config:
      updates-enabled: true
      fs-cache-path: $dynamic-config-cache-path
      fs-task-processor: fs-task-processor

Usage example:

namespace myservice::smth {
 
inline const dynamic_config::Key kMyConfig{"SAMPLE_INTEGER_FROM_RUNTIME_CONFIG",
                                           42};
 
int Component::DoSomething() const {
  // Getting a snapshot of dynamic config.
  const auto runtime_config = config_.GetSnapshot();
  return runtime_config[kMyConfig];
}
 
}  // namespace myservice::smth

Examples

components/component_sample_test.cpp.

Definition at line 67 of file component.hpp.

Inheritance diagram for components::DynamicConfig:

Classes
class	NoblockSubscriber
	Allows to subscribe to DynamicConfig updates without waiting for the first update to complete. Primarily intended for internal use. More...

Public Member Functions
	DynamicConfig (const ComponentConfig &, const ComponentContext &)
dynamic_config::Source	GetSource ()
const dynamic_config::DocsMap &	GetDefaultDocsMap () const
ComponentHealth	GetComponentHealth () const override
void	OnAllComponentsLoaded () override
void	OnAllComponentsAreStopping () override

Static Public Member Functions
static yaml_config::Schema	GetStaticConfigSchema ()

Static Public Attributes
static constexpr std::string_view	kName = "dynamic-config"
	The default name of components::DynamicConfig.

Protected Types
using	LoggableComponentBase = ComponentBase
	Legacy alias, use ComponentBase instead.

Member Typedef Documentation

LoggableComponentBase

using components::ComponentBase::LoggableComponentBase = ComponentBase

protectedinherited

Legacy alias, use ComponentBase instead.

Definition at line 69 of file component_base.hpp.

Member Function Documentation

GetComponentHealth()

ComponentHealth components::ComponentBase::GetComponentHealth ( ) const

inlineoverridevirtualinherited

Override this function to inform the world of the state of your component.

Warning

The function is called concurrently from multiple threads.

Reimplemented from components::RawComponentBase.

Definition at line 35 of file component_base.hpp.

GetDefaultDocsMap()

const dynamic_config::DocsMap & components::DynamicConfig::GetDefaultDocsMap

(

)

const

Get config defaults with overrides applied. Useful in the implementation of custom config clients. Most code does not need to deal with these

GetSource()

dynamic_config::Source components::DynamicConfig::GetSource

(

)

Use dynamic_config::Source to get up-to-date config values, or to do something special on config updates

Examples

components/component_sample_test.cpp.

OnAllComponentsAreStopping()

void components::ComponentBase::OnAllComponentsAreStopping ( )

inlineoverridevirtualinherited

Component may use this function to stop doing work before the stop of the components that depend on it.

Base components may override it and make final to do some work before the derived object constructor is called. Don't use it otherwise.

Reimplemented from components::RawComponentBase.

Reimplemented in urabbitmq::ConsumerComponentBase, and components::Server.

Definition at line 60 of file component_base.hpp.

OnAllComponentsLoaded()

void components::ComponentBase::OnAllComponentsLoaded ( )

inlineoverridevirtualinherited

Component may use this function to finalize registration of other components that depend on it (for example, handler components register in server component, and the latter uses OnAllComponentsLoaded() to start processing requests).

Base components may override it and make final to do some work after the derived object constructor is called. Don't use it otherwise.

Reimplemented from components::RawComponentBase.

Reimplemented in urabbitmq::ConsumerComponentBase, components::Server, and server::handlers::Ping.

Definition at line 53 of file component_base.hpp.

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The documentation for this class was generated from the following file:

• userver/dynamic_config/storage/component.hpp