Feature Toggles Management library

Table of Contents

• Overview
  • Every Feature Toggle
  • How to add
  • Servlet web-based example
  • Reactive web-based example
• Parent documentation

Overview

Feature Toggles Management facade library intended to unify interaction model with possibly different implementation providers.

Current library module is designed to provide basic capabilities and a common conventions set for feature management to being able to express/prescribe feature toggle object to lookup and validate (current version is mainly biased to the AppConfiguration Feature Manager variation).

Every Feature Toggle description object should be equipped with required lookup metadata reflecting and revealing the following information:

• featureLookupKey - feature manager key/alias in terms of underlying cache specific implementation to locate snapshot/cached instance in order for ensure that feature flags should be consistent across the entire request as configuration values can change in real-time;

• name - name of evaluated Feature Toggle object/instance real data owner - do not confuse with above property - ownerId is key property and used as a partition key for the audit store Cosmos container;

• userId - reflects user specific identifier attribute value;

• groups - used to evaluate specified feature flag on user to belong to a certain group condition;

• defaultValue - default evaluation value for specified feature flag.

In order to add Feature Toggles Management facade library to the project follow below steps:

• add library dependency to the required project;

• Turn on feature lookup functionality by placing below configuration properties set under bootstrap configuration file for specific project:

az-feature-management:
  configuration:
    enabled: true
    snapshot-enabled: true
    type: APP_CONFIGURATION

Servlet web-based application usage example:

private final FeatureLookup featureLookup;

@PostMapping("/resolve")
@PreAuthorize("@verifyAccess(authentication)")
public ExampleDTO resolveIdentity(@RequestBody @Validated ExampleRequest request) {
    FeatureLookup.FeatureOptionsBuilderProvider options = builder -> builder
            .featureLookupKey(FeatureManagementEnvironmentType.WEB_SERVLET_BLOCKING.getFeatureLookupKey(Stream::empty))
            .name("TestFeatureEnabled")
            .userId(request.getId())
            .defaultValue(true)
            .groups(Set.of());

    if (featureLookup.lookup(options)) {
        return exampleService.resolveExample(request);
    } else {
        throw new IllegalArgumentException();
    }
}

Reactive web-based application usage example:

private final FeatureLookup featureLookup;

public Mono<Example> fetchExample(String id, DataFetchingEnvironment env) {
    return authenticationRepository.getAuthentication(GraphQLUtils.getExchange(env))
            .transformDeferredContextual((auth, ctx) ->
                auth.flatMap(principal -> {
                    String exampleId = Optional.ofNullable(id).orElseGet(principal::getId);

                    FeatureLookup.FeatureOptionsBuilderProvider options = builder -> builder
                            .featureLookupKey(FeatureManagementEnvironmentType.WEB_REACTIVE
                                    .getFeatureLookupKey(ctx::stream))
                            .name("TestFeatureEnabled")
                            .userId(userId)
                            .defaultValue(true)
                            .groups(Set.of());

                    return featureLookup.lookupAsync(options)
                            .flatMap(isTestFeatureEnabled -> {
                                if (isTestFeatureEnabled) {
                                    return exampleCrudApi.findExampleByIdUsingGET(principal.getRunAsHeader(), exampleId);
                                } else {
                                    throw new IllegalArgumentException();
                                }
                            });
                }));
}

In order to override remote value of feature and use you own local value:

• update service bootstrap-local.yaml/bootstrap.yaml

    az-feature-management:
        configuration:
            enabled: true
            type: LOCAL_CONFIGURATION
            features: ./path_to_features.json

• add under app resources folder you own features like './sample_features.json'