tveal / feature-toggles

Feature toggles (or flags) in pursuit of Trunk Based Development.

Feature Toggles

Driving Idea: Have a centralized toggle server with in-memory db and REST API for retrieving real-time toggle values.

Why? The pursuit (and necessity) of Trunk Based Development. See Feature Flags, especially Runtime Switchable.

Goals:

• server:
  • REST API for toggle values
  • provide consumable client jar
  • Have UI for toggle management (set, add, remove)
  • Have in-memory and persistent toggle storage for server
  • SSE impl for toggle changes
• client jar (consumed in client-service):
  • Provide a method such as ToggleClient.isFeatureEnabled("my-toggle") that gets the first available value:
    1. server value
    2. application.properties on classpath of client-service
    3. default to false

---

Build Things

toggle-server and api's

The toggle-server project contains the api-<lang>-<protocol> subprojects, collectively producing:

• build/libs/toggle-server-${version}.war
• api-java-rest/build/libs/api-java-rest-${version}.jar
• api-java-sse/build/libs/api-java-sse-${version}.jar
• ...

# from toggle-server directory
./gradlew clean build

sample-client-service

# from sample-client-service directory
./gradlew clean build

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Run Things Locally

Option 1

Fast dev workflow; Run Server, UI, and Sample Client separately

Server

# from toggle-server directory
./gradlew bootRun

Request toggle value with a url like:

http://localhost:8090/toggle-server/get-toggle?toggleId=my-feature

UI

Allows file-watching for ui changes; No rebuilds needed.

# from toggle-server/ui directory
npm start

On startup, this should automatically open the ui at http://localhost:3000/

Sample Client Service

# from sample-client-service directory
./gradlew bootRun

Visit the following url:

http://localhost:8900/sample-client-service

Option 2

Slower startup; Run Server/UI as one deployable war. Currently, cargoRunLocal gradle task doesn't show the slf4j logs. Haven't gotten around to configuring log properties.

Server + UI

# from toggle-server directory
./gradle cargoRunLocal -i

Visit the following url:

http://localhost:8090/toggle-server/