spring-boot

Flagent Spring Boot Sample

Minimal Spring Boot application using the Flagent Spring Boot Starter for feature flag evaluation.

Features

• Single evaluation - Evaluate a flag via FlagentEvaluationFacade
• EntityContext - Constraint-based targeting (country, tier)
• Batch evaluation - Evaluate multiple flags for multiple entities
• Caching - Optional in-memory cache (Caffeine)

Requirements

• JDK 21+
• Flagent backend running on http://localhost:18000

Setup

1. Start Flagent Backend

From repo root:

./gradlew :backend:run

2. Run Sample

From repo root:

./gradlew :sample-spring-boot:bootRun

The sample starts on http://localhost:8080.

Configuration

See src/main/resources/application.yml:

server:
  port: 8080

flagent:
  base-url: http://localhost:18000
  cache:
    enabled: true
    ttl-ms: 60000

Override flagent.base-url if Flagent runs elsewhere.

Usage

Single Evaluation

# Basic
curl "http://localhost:8080/eval?flagKey=my_flag&entityId=user-1"

# With entityContext for constraint-based targeting
curl "http://localhost:8080/eval?flagKey=my_flag&entityId=user-1&country=US&tier=premium"

Batch Evaluation (POST)

curl -X POST http://localhost:8080/eval/batch \
  -H "Content-Type: application/json" \
  -d '{
    "entities": [
      {"entityID": "user1", "entityType": "user", "entityContext": {"country": "US", "tier": "premium"}},
      {"entityID": "user2", "entityType": "user", "entityContext": {"country": "EU"}}
    ],
    "flagKeys": ["my_flag", "experiment_1"]
  }'

Batch Demo (GET)

Convenience endpoint with pre-defined entities:

curl "http://localhost:8080/eval/batch-demo?flagKey=my_flag"

Endpoints

Endpoint	Method	Description
/eval	GET	Single evaluation. Params: flagKey, entityId, entityType, country, tier
/eval/batch	POST	Batch evaluation (JSON body)
/eval/batch-demo	GET	Batch demo with sample entities

Constraint-Based Targeting

When your flag has segments with constraints (e.g., country EQ US), pass country and tier as query params. The evaluator matches the segment and returns the assigned variant.

Project Structure

spring-boot/
├── src/main/java/com/flagent/sample/
│   ├── EvalController.java      # Evaluation endpoints
│   └── SpringBootSampleApplication.java
├── src/main/resources/
│   └── application.yml
├── build.gradle.kts
└── README.md

Troubleshooting

• Connection refused: Ensure Flagent backend is running at http://localhost:18000
• 404 on evaluation: Create a flag in Flagent UI first (e.g., key my_flag)

License

Apache 2.0 - See parent project license