azure_app_config 0.11.0

A Dart package to communicate more easily with Microsoft Azure App Configuration.

Azure App Configuration

This package makes it easier to communicate with Microsoft Azure App Configuration KeyValue and FeatureFlag resources.

Installation

To use this plugin, add azure_app_config to your pubspec.yaml file.

Authentication

There are two methods of using Azure App Configuration:

1. (simple) Use the connection string which can be obtained from the App Configuration Dashboard under 'Access keys'. If the connection string is invalid or not specified, an ArgumentError will occur.

2. (complex) Use the factory constructor AzureRemoteService.customAuthentication() which enables you to prove a custom way of signing requests.

Example

import 'dart:developer' as developer;

import 'package:azure_app_config/azure_app_config.dart';

void main() async {
    const exampleKey = 'example_key';
    const exampleLabel = 'example_label';

    // Creating an instance needs a connection String. This can be
    // obtained through the Azure Portal, under "Access Keys".
    final service = AzureRemoteService(connectionString: '<CONNECTION_STRING>');

    // Getting a keyvalue
    late KeyValue keyValue;

    try {
        keyValue = await service.getKeyValue(key: exampleKey, label: exampleLabel);
    } catch (err) {
        // Handle any exceptions that might occur when interacting with the Azure
        // service
        developer.log('Error occurred while getting key value: $err');
    }

    // Now you can retrieve any property of the keyValue, for instance
    developer.log(keyValue.value);

    // If the KeyValue is a FeatureFlag, you can use .asFeatureFlag()
    // to get the properties of the FeatureFlag
    try {
        final featureFlag = keyValue.asFeatureFlag();

        // To check if the featureflag is enabled, use
        developer.log('${featureFlag.enabled}');

        // .asFeatureFlag() will throw this exception if it's unable to parse.
    } on AzureKeyValueNotParsableAsFeatureFlagException {
        rethrow;
    }

    // To check if a featureflag is enabled while parsing the featurefilters, use

    try {
        final isFeatureEnabled =
            await service.getFeatureEnabled(key: exampleKey, label: exampleLabel);

        developer.log('$isFeatureEnabled');
    } catch (err) {
        // Handle any exceptions that might occur when interacting with the Azure
        // service
        developer.log('Error occurred while checking if feature is enabled: $err');
    }

    // To find FeatureFlags based on a key and label filter use findKeyValuesBy().
    // This example searches for the keyValues that start with '.appconfig.'
    // without a label:
    try {
        final keyValues = await service.findKeyValuesBy(
            keyFilter: '.appconfig.*',
            labelFilter: AzureFilters.noLabel,
        );

        for (final keyValue in keyValues) {
            developer.log(keyValue.value);
        }

        // When an invalid filter has been provided, for example, '.appconfig.**',
        // an [AzureFilterValidationException] is thrown.
    } on AzureFilterValidationException catch (e) {
        developer.log(e.message ?? '');
    }
}

---

FeatureFilters

This package currently has 2 built-in FeatureFilters based on the defaults which can be found in the App Configuration dashboard:

Microsoft.Targeting -> Enable a flag based on a percentage. Use 'Default Percentage' for this. The Groups section is still a work in progress, and is not included in this library.

Microsoft.TimeWindow -> Enable a feature flag during a specified window of time.

Implement your own FeatureFilter

This package enables you to create custom FeatureFilters by extending the FeatureFilter class. For example, this is how the Percentage filter is implemented:

class Percentage extends FeatureFilter {
  Percentage() : super(name: "Microsoft.Targeting");

  @override
  bool evaluate(Map<String, dynamic> parameters) {
    final value = parameters['Audience']['DefaultRolloutPercentage'] as int;
    final random = Random().nextInt(100);

    return random < value;
  }

Register the FeatureFilter by calling service.registerFeatureFilter(filter). The build-in filters are automatically registered.

More Information

For more information about Azure App Configuration, take a look at the following resources.

• Azure App Configuration Overview
• Feature Management Overview

Feel free to submit any pull requests!

Package created by Walter Tesevic commissioned by Ordina