Feature flags

[richardelms]

This pull request introduces first-class support for feature flags in the Bugsnag Java notifier, enabling users to annotate error reports with feature flag information for better experimentation and release tracking. The changes add new APIs for managing feature flags at the configuration, client, and report levels, and ensure feature flag data is included in error reports. Additionally, the Logback integration is updated to support feature flags via configuration.

Feature flag support (core):

• Added a new FeatureFlag class to represent feature flags with a name and optional variant.
• Introduced a thread-safe FeatureFlagStore class to manage feature flag storage and merging logic.
• Updated the Configuration, Bugsnag, and Report classes to include APIs for adding, clearing, and retrieving feature flags, and to ensure flags are propagated and merged correctly at all levels. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11]

Logback integration:

• Enhanced BugsnagAppender to allow feature flags to be configured via logback.xml and manipulated at runtime, ensuring they are added to the Bugsnag client and included in error reports. [1] [2] [3] [4]

These changes provide a comprehensive and flexible way to track feature flag exposure in error reports, supporting use cases like A/B testing and gradual rollouts.

References:
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17]

[Copilot]

Pull request overview

This PR implements feature flag functionality across the Bugsnag Java SDK, allowing users to annotate error reports with information about active experiments or A/B tests. Feature flags can be set at configuration, client, and event levels, with support for optional variants and proper inheritance/override behavior.

• Added core FeatureFlag and FeatureFlagStore classes to manage feature flags with insertion order preservation
• Integrated feature flags into Configuration, Bugsnag, and Report classes with add/clear operations
• Added logback appender support for configuring feature flags via XML

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
bugsnag/src/main/java/com/bugsnag/FeatureFlag.java	Core feature flag model with name and optional variant
bugsnag/src/main/java/com/bugsnag/FeatureFlagStore.java	Thread-safe storage maintaining insertion order
bugsnag/src/main/java/com/bugsnag/Configuration.java	Added feature flag methods to configuration
bugsnag/src/main/java/com/bugsnag/Bugsnag.java	Added client-level feature flag support with store initialization
bugsnag/src/main/java/com/bugsnag/Report.java	Added event-level feature flags with inheritance from config and client
bugsnag/src/main/java/com/bugsnag/BugsnagAppender.java	Added logback XML configuration support for feature flags
bugsnag/src/main/java/com/bugsnag/logback/LogbackFeatureFlag.java	Configuration bean for logback XML parsing
bugsnag/src/test/java/com/bugsnag/*.java	Comprehensive unit tests for feature flag functionality
features/*.java	End-to-end test scenarios for feature flags
features/feature_flags.feature	Cucumber test specifications

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[Copilot]

Pull request overview

Copilot reviewed 19 out of 19 changed files in this pull request and generated no new comments.

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