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Theconfigmanager is a package that provides a robust and efficient way to manage andhandle configuration data in your application. It's designed to load configurationsperiodically from arbitrary sources, such as a file, a database, or a web service. Themodule also provides monitoring on configuration changes and allows instant callback ofa registered listener.

• Refreshes configuration data at regular intervals specified
• Provides methods for accessing configuration data
• Supports configuration change listeners for efficient handling of updates
• Includes a default FileProvider for loading configurations from a file
• Allows for customizable options and arbitrary sources

ConfigManager is designed with a 4-level hierarchy:

• ConfigManager:
  • Holds aProvider for loading of all configurations
  • Compares two versions of config and notify registered listeners if there's any difference
  • Provides APIs to reload config, retrieve certain config value/item, dump to files, etc.
• Provider:
  • Responsible for loading configurations from desired source(s)
  • Returns all configs in the form ofmap[string]iface.ConfigValue to the calling ConfigManager
• ConfigValue:
  • Holding a set ofiface.ConfigValueItem
    • The builtinConfigValueImpl is designed with amap[iface.ItemType]iface.ConfigValueItem
  • Provides APIs to retrieve certain config item
• ConfigValueItem:
  • Holds specific configurations according to requirement

You can go directly to theexample/main.go for a runnable example of the following steps.

configmanager ships with aFileProvider which loads from a config file in JSON format.

We'll begin with a JSON config file below (save it asconfig.json):

{  "test1": {    "item-max-retry": 1,    "item-max-limit": 2,    "item-service-name": "service_name"  }}

Import the package into your application.

import ("github.com/cloudwego/configmanager""github.com/cloudwego/configmanager/configvalue/items""github.com/cloudwego/configmanager/fileprovider""github.com/cloudwego/configmanager/iface)

Initialize a FileProvider

// define your own item type for builtin itemsconst TypeItemMaxRetry iface.ItemType = "item-max-retry"const TypeItemMaxLimit iface.ItemType = "item-max-limit"const TypeItemServiceName iface.ItemType = "item-service-name"itemFactory := fileprovider.NewItemFactory(map[iface.ItemType]iface.ItemInitializer{    TypeItemMaxRetry:    items.NewItemInt64,    TypeItemMaxLimit:    items.NewItemInt64, // an item can be used with multiple item types    TypeItemServiceName: items.NewItemString,    // you can register your own ConfigValueItem(s) here})provider := fileprovider.NewFileProvider(    fileprovider.WithFileProviderItemFactory(itemFactory),    fileprovider.WithFileProviderPath("config.json"),)

Create a new instance of ConfigManager with the desired options.

manager := configmanager.NewConfigManager([]configmanager.ConfigManagerOption{    configmanager.WithRefreshInterval(10 * time.Second),    configmanager.WithConfigProvider(provider),)

Register configuration change listeners as needed:

manager.RegisterConfigChangeListener("unique-id-for-each-listener", func(change iface.ConfigChange) {    // update something according to the change    log.Println("Change:", string(util.MustJsonMarshal(change)))})

Refresh the configuration data manually if necessary.

// send a refresh signal and return immediately:manager.Refresh()// or if you need to wait until the loading completes:manager.RefreshAndWait()

Access and retrieve configuration using the provided methods:

// define your iface.ConfigKey with a ToString() methodconfigKey := "SomeConfigKey"// it's recommended to retrieve the ConfigValueItem directly:maxRetryItem, err := manager.GetConfigItem(configKey, TypeItemMaxRetry)if err == nil {    maxRetry := maxRetryItem.(*items.ItemInt64).Value()    ...}// you can also retrieve the ConfigValueImpl for other purposesconfigValue, err := manager.GetConfig(configKey)if err == nil {    maxRetryLimit, err := configValue.GetItem(TypeItemMaxLimit)    // or call GetItemOrDefault() with a default item value    serviceName := configValue.GetItemOrDefault(TypeItemServiceName, items.CopyDefaultItemString())}

Export the configuration data to a file using theDump method.

err := manager.Dump("local_dump.json")

Basic items like ItemBool, ItemInt64, ItemPair, ItemString is shipped with this package. You candefine your own ItemType for simple configuration only holding basic go type values with these items.

If you need items more complicated, just create your own items implementing theiface.ConfigValueItem.It might be easier to copy from items.ItemPair and make modifications.

The built-inConfigValueImpl mainly focuses on its extensibility, which allows for extending of newtypes of ConfigValueItem without modifying ConfigValueImpl and FileProvider, at the cost of increasingits complexity (harder to comprehend).

If you wish, you can write your own implementation ofiface.ConfigValue. It's not recommended, becauseit's not compatible with the builtin FileProvider.

Available Options are:

• WithFileProviderPath
  • The specified file will be used to load the configuration data.
• WithFileProviderItemFactory
  • The ItemFactory is responsible for creating new instances of ConfigValueItem when loading data from the file.
• WithFileProviderLogger
  • This option sets a custom logger implementation for the FileProvider.
  • By default, the logger uses log.Printf.

You can implement your own Provider to load config from other sources, as long as it implements theiface.ConfigProvider.

It's recommended to useConfigValueImpl as the value in the returned config map, thus you can easilyswitch your provider toFileProvider.

Available Options are:

• WithRefreshInterval
  • This option sets the interval for refreshing the configuration data.
  • If not set, the interval defaults to 10 seconds.
• WithConfigProvider
  • This option sets the given ConfigProvider as the source for configuration data.
• WithErrorLogger
  • This option sets a custom error logger for the ConfigManager instance.
  • If not set, the logger defaults to log.Printf.
• WithConfigSerializer
  • This option sets a custom ConfigSerializer for the ConfigManager.
  • If not set, the serializer defaults to util.JSONSerializer.