description: Chaos Monkey Module

Chaos Monkey

The chaos-monkey module in light-chaos-monkey allows developers and operators to inject various types of failures (assaults) into a running service to test its resilience. It provides API endpoints to query and update assault configurations dynamically at runtime.

Core Components

ChaosMonkeyConfig

Configuration class that loads settings from chaos-monkey.yml. It defines whether the chaos monkey capability is enabled globally.

ChaosMonkeyGetHandler

A LightHttpHandler that retrieves the current configuration of all registered assault handlers.

• Endpoint: GET /chaosmonkey (typically configured via openapi.yaml or handler.yml)
• Response: A JSON object containing the current configurations for Exception, KillApp, Latency, and Memory assaults.

ChaosMonkeyPostHandler

A LightHttpHandler that allows updating a specific assault configuration on the fly.

• Endpoint: POST /chaosmonkey?assault={handlerClassName}
• Request: assault query parameter specifying the target handler class (e.g., com.networknt.chaos.LatencyAssaultHandler), and a JSON body matching that handler’s configuration structure.
• Behavior: Updates the static configuration of the specified assault handler and triggers a re-registration of the module config.

Assault Types

• ExceptionAssault: Injects exceptions into request handling.
• KillappAssault: Terminates the application instance (use with caution!).
• LatencyAssault: Injects artificial delays (latency) into requests.
• MemoryAssault: Consumes heaps memory to simulate memory pressure/leaks.

Configuration

The module itself is configured via chaos-monkey.yml.

Key Settings:

• enabled: Global switch to enable or disable the chaos monkey endpoints (default: false).

Example Configuration:

enabled: true

Each assault type has its own specific configuration (e.g., latency-assault.yml, exception-assault.yml) which controls the probability and specifics of that attack.