Working with remote configuration has become a standard part of the development process for almost any application. Depending on the complexity of the application, several requirements for such functionality may arise, including:
- convenient syntax for declaring configuration elements
- the ability to separate configuration into different files for different features
- the ability to make the configuration local-only during active feature development
- support for multiple data sources for remote config
- the ability to view a list of all configurations and modify their values for debugging purposes
- logging the value and its source when accessing the configuration, as well as logging non-critical errors
We have made every effort to meet all these requirements in the development of Konfeature.
Add the dependency:
repositories {
mavenCentral()
}
dependencies {
implementation("com.redmadrobot.konfeature:konfeature:<version>")
}Defines a set of configuration elements, where each element is defined using a delegate. There are two types of delegates:
by toggle(...)- used for elements of typeBooleanby value(...)- used for elements of any other type
class ProfileFeatureConfig : FeatureConfig(
name = "profile_feature_config",
description = "Config of features for profile usage"
) {
val isProfileFeatureEnabled: Boolean by toggle(
key = "profile_feature",
description = "show profile entry point for user",
defaultValue = false,
)
val profileFeatureTitle: String by value(
key = "profile_feature_title",
description = "title of profile entry point button",
defaultValue = "Feature number nine",
sourceSelectionStrategy = SourceSelectionStrategy.Any
)
val profileButtonAppearDuration: Long by value(
key = "profile_button_appear_duration",
description = "duration of profile button appearing in ms",
defaultValue = 200,
sourceSelectionStrategy = SourceSelectionStrategy.Any
)
}The configuration requires specifying:
name- the name of the configurationdescription- a detailed description of the configuration
Each configuration element requires specifying:
key- used to retrieve the value of the element from aSourcedescription- a detailed description of the elementdefaultValue- used if the value cannot be found in aSourcesourceSelectionStrategy- the strategy for selecting aSourceusing SourceSelectionStrategy
After that, you need to register the configuration in Konfeature:
val profileFeatureConfig: FeatureConfig = ProfileFeatureConfig()
val konfeatureInstance = konfeature {
register(profileFeatureConfig)
}Similarly, you can add multiple configurations, for example, for each module, when organizing multi-modularity by features.
An abstraction over the value source for configuration elements.
public interface FeatureSource {
public val name: String
public fun get(key: String): Any?
}name- source nameget(key: String)- logic for getting values bykey
Example implementation based on FirebaseRemoteConfig:
class FirebaseFeatureSource(
private val remoteConfig: FirebaseRemoteConfig
) : FeatureSource {
override val name: String = "FirebaseRemoteConfig"
override fun get(key: String): Any? {
return remoteConfig
.getValue(key)
.takeIf { source == FirebaseRemoteConfig.VALUE_SOURCE_REMOTE }
?.let { value: FirebaseRemoteConfigValue ->
value.getOrNull { asBoolean() }
?: value.getOrNull { asString() }
?: value.getOrNull { asLong() }
?: value.getOrNull { asDouble() }
}
}
private fun FirebaseRemoteConfigValue.getOrNull(
getter: FirebaseRemoteConfigValue.() -> Any?
): Any? {
return try {
getter()
} catch (error: IllegalArgumentException) {
null
}
}
}After that, you need to add the Source in Konfeature:
val profileFeatureConfig: FeatureConfig = ProfileFeatureConfig()
val source: FeatureSource = FirebaseFeatureSource(remoteConfig)
val konfeatureInstance = konfeature {
addSource(source)
register(profileFeatureConfig)
}Similarly, you can add multiple sources, for example, Huawei AppGallery, RuStore, or your own backend.
You can configure the retrieval of an element's value from the source more flexibly by using the sourceSelectionStrategy parameter:
val profileFeatureTitle: String by value(
key = "profile_feature_title",
description = "title of profile entry point button",
defaultValue = "Feature number nine",
sourceSelectionStrategy = SourceSelectionStrategy.Any
)Where sourceSelectionStrategy filters the available data sources.
public fun interface SourceSelectionStrategy {
public fun select(names: Set<String>): Set<String>
public companion object {
public val None: SourceSelectionStrategy = SourceSelectionStrategy { emptySet() }
public val Any: SourceSelectionStrategy = SourceSelectionStrategy { it }
public fun anyOf(vararg sources: String): SourceSelectionStrategy = SourceSelectionStrategy { sources.toSet() }
}
}The select(...) method receives a list of available Source names and returns a list of sources from which the configuration element can retrieve a value.
For most scenarios, predefined implementations will be sufficient:
SourceSelectionStrategy.None- prohibits taking values from any source, i.e., the value specified indefaultValuewill always be usedSourceSelectionStrategy.Any- allows taking values from any sourceSourceSelectionStrategy.anyOf("Source 1", ... ,"Source N")- allows taking values from the specified list of sources
Important
By default, SourceSelectionStrategy.None is used!
Allows intercepting and overriding the value of the element.
public interface Interceptor {
public val name: String
public fun intercept(valueSource: FeatureValueSource, key: String, value: Any): Any?
}name- the name of the interceptorintercept(valueSource: FeatureValueSource, key: String, value: Any): Any?- called when accessing the element withkeyandvaluefromvalueSource(Source(<name>), Interceptor(<name>), Default), and returns its new value ornullif it doesn't change
Example of implementation based on DebugPanelInterceptor:
class DebugPanelInterceptor : Interceptor {
private val values = mutableMapOf<String, Any>()
override val name: String = "DebugPanelInterceptor"
override fun intercept(valueSource: FeatureValueSource, key: String, value: Any): Any? {
return values[key]
}
fun setFeatureValue(key: String, value: Any) {
values[key] = value
}
fun removeFeatureValue(key: String) {
values.remove(key)
}
}After that, you need to add the Interceptor in Konfeature:
val profileFeatureConfig: FeatureConfig = ProfileFeatureConfig()
val source: FeatureSource = FirebaseFeatureSource(remoteConfig)
val debugPanelInterceptor: Interceptor = DebugPanelInterceptor()
val konfeatureInstance = konfeature {
addSource(source)
register(profileFeatureConfig)
addInterceptor(debugPanelInterceptor)
}Similarly, you can add multiple interceptors.
public interface Logger {
public fun log(severity: Severity, message: String)
public enum class Severity {
WARNING, INFO
}
}The following events are logged:
- key, value, and its source when requested
Get value 'true' by key 'profile_feature' from 'Source(name=FirebaseRemoteConfig)'
SourceorInterceptorreturns an unexpected type forkey
Unexpected value type for 'profile_button_appear_duration': expected type is 'kotlin.Long', but value from 'Source(name=FirebaseRemoteConfig)' is 'true' with type 'kotlin.Boolean'
Example of implementation based on Timber:
class TimberLogger: Logger {
override fun log(severity: Severity, message: String) {
if (severity == INFO) {
Timber.tag(TAG).i(message)
} else if (severity == WARNING) {
Timber.tag(TAG).w(message)
}
}
companion object {
private const val TAG = "Konfeature"
}
}After that, you need to add the Logger in Konfeature:
val profileFeatureConfig: FeatureConfig = ProfileFeatureConfig()
val source: FeatureSource = FirebaseFeatureSource(remoteConfig)
val debugPanelInterceptor: Interceptor = DebugPanelInterceptor()
val logger: Logger = TimberLogger()
val konfeatureInstance = konfeature {
addSource(source)
register(profileFeatureConfig)
addInterceptor(debugPanelInterceptor)
setLogger(logger)
}Konfeature contains information about all registered FeatureConfig in the form of spec:
public interface Konfeature {
public val spec: List<FeatureConfigSpec>
public fun <T : Any> getValue(spec: FeatureValueSpec<T>): FeatureValue<T>
}This allows you to obtain information about added configurations as well as the current value of each element:
val konfeatureInstance = konfeature {...}
val featureConfigSpec = konfeatureInstance.spec[0]
val featureSpec = featureConfigSpec.values[0]
val featureValue = konfeatureInstance.getValue(featureSpec)This can be useful for use in the DebugPanel
The value of the configuration element is determined in the following order:
defaultValueandDefaultsource are assigned.- Using
sourceSelectionStrategy, a list ofSourcesfrom which a value can be requested is determined. - Search the list of
Sourcesin the order they were added toKonfeature, stopping at the first occurrence of the element bykey. Upon successful search, the value fromSourceis assigned withSource(name=SourceName)source. - Search the list of
Interceptorsin the order they were added toKonfeature. IfInterceptorreturns a value other thannull, this value is assigned withInterceptor(name=InterceptorName)source.
Merge requests are welcome.
For major changes, please open an issue first to discuss what you would like to change.