components::DynamicConfig Class Reference

Table of Contents

• Detailed Description
• Behavior on missing configs
• Behavior on config parsing failure
• Static options
• Static configuration example:
• Usage example:
• Classes
• Public Member Functions
• Static Public Member Functions
• Static Public Attributes
• Member Function Documentation
• GetDefaultDocsMap()
• GetSource()

#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:

    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:

Collaboration 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
Public Member Functions inherited from components::DynamicConfigUpdatesSinkBase
	DynamicConfigUpdatesSinkBase (const components::ComponentConfig &, const components::ComponentContext &)
Public Member Functions inherited from components::LoggableComponentBase
	LoggableComponentBase (const ComponentConfig &, const ComponentContext &)
	LoggableComponentBase (LoggableComponentBase &&)=delete
	LoggableComponentBase (const LoggableComponentBase &)=delete
	~LoggableComponentBase () override=default
ComponentHealth	GetComponentHealth () const override
void	OnLoadingCancelled () override
void	OnAllComponentsLoaded () override
void	OnAllComponentsAreStopping () override

Static Public Member Functions
static yaml_config::Schema	GetStaticConfigSchema ()
Static Public Member Functions inherited from components::LoggableComponentBase
static yaml_config::Schema	GetStaticConfigSchema ()

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

Member Function Documentation

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.

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

• userver/dynamic_config/storage/component.hpp