@cap-js-community/feature-toggle-library

SAP BTP Feature Toggle Library

SAP BTP feature toggle library enables Node.js applications using the SAP Cloud Application Programming Model to maintain live-updatable feature toggles via Redis.

Getting Started (CAP Feature Toggles)

• Set up project with @sap/cds.

• Install library:

  npm install --save @cap-js-community/feature-toggle-library
  

• For CAP Feature Toggles everything is configured automatically.

• The library acts as a CDS-Plugin and registers a FeatureService, which can be used to check and update toggles.

• For details see Example CAP Server.

Getting Started (Custom Configuration)

• Same as previous section.

• Write toggles.yaml configuration file:

  # info: check api priority; 0 means access is disabled
  /check/priority:
    type: number
    fallbackValue: 0
    validations:
      - scopes: [user, tenant]
      - regex: '^\d+$'
  

• Add configuration path to package.json:

  {
    "cds": {
      "featureToggles": {
        "configFile": "./toggles.yaml"
      }
    }
  }
  

• Write usage code in handlers:

  const toggles = require("@cap-js-community/feature-toggle-library");
  
  const priorityHandler = async (context) => {
    const user = context.user.id;
    const tenant = context.tenant;
    const value = toggles.getFeatureValue("/check/priority", { user, tenant });
    if (value <= 0) {
      return context.reject("blocked");
    } else if (value < 10) {
      return context.reply("welcome");
    } else {
      return context.reply("very welcome");
    }
  };
  

Features

• Maintain feature toggle states consistently across multiple app instances.
• Feature toggle changes are published from Redis to subscribed app instances with publish/subscribe pattern PUB/SUB.
• Horizontal app scaling is supported and new app instances will start with the correct state, or fallback values, if they cannot connect to Redis.
• Feature toggle values can be changed specifically for accessors with certain scopes, e.g., for specific tenants, users,...
• Users can register change handler callbacks for specific toggles.
• Users can register custom input validation callbacks for specific toggles.
• Works as a CDS-Plugin and provides a REST service to read and manipulate toggles.

Peers

• CAP Extensibility Feature Toggles
• SAP Feature Flags Service

Documentation

Head over to our Documentation to learn more.

Support, Feedback, Contributing

This project is open to feature requests/suggestions, bug reports etc. via GitHub issues. Contribution and feedback are encouraged and always welcome. For more information about how to contribute, the project structure, as well as additional contribution information, see our Contribution Guidelines.

Code of Conduct

We as members, contributors, and leaders pledge to make participation in our community a harassment-free experience for everyone. By participating in this project, you agree to abide by its Code of Conduct at all times.

Licensing

Copyright 2023 SAP SE or an SAP affiliate company and feature-toggle-library contributors. Please see our LICENSE for copyright and license information. Detailed information including third-party components and their licensing/copyright information is available via the REUSE tool.

Changelog

v1.2.2 - 2024-11-14

Changed

• the initialization log of the library will now show the unique name used. this name is used to derive both the redis storage key and pub/sub channel.

Fixed

• internal naming cleanup and consistency work.