npm package: @sourceloop/feature-toggle-service
Description: A service that provides feature toggle functionality
Author: Sourcefuse
Latest version: 8.0.6

# @sourceloop/feature-toggle-service

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## Overview

Microservice that provides functionality to maintain feature flags at various levels. Initial support for system level, tenant level and user level is provided.

## Working and Flow

This service provides CRUD APIs to insert values into the feature-toggle specific data tables that can be read while making the decision if a particular feature is allowed or not to the user.
This feature is an extension of the feature-toggle package -- @sourceloop/feature-toggle that provides a method level decorator which will check if that particular API is accessible or not.

Initial implementation for system level, tenant level and user level feature flag is provided.

## Installation

```bash

npm i @sourceloop/feature-toggle-service
```

## Usage

- Create a new Loopback4 Application (If you don't have one already) lb4 testapp
- Install the service - npm i @sourceloop/feature-toggle-service
- Set up the [environment variables](#environment-variables)
- Run the [migrations](#migrations). (this will create respective tables in your Database)
- Add the `FeatureToggleServiceComponent` to your Loopback4 Application (in `application.ts`).
  ```typescript
  // import the FeatureToggleServiceComponent
  import {FeatureToggleServiceComponent} from '@sourceloop/feature-toggle-service';
  // add controllers to your application (optional)
  this.bind(FeatureToggleBindings.Config).to({
    bindControllers: true,
    useCustomSequence: false,
  });
  // add Component for FeatureToggleService
  this.component(FeatureToggleServiceComponent);
  ```
- Set up a [Loopback4 Datasource](https://loopback.io/doc/en/lb4/DataSource.html) with `dataSourceName` property set to
  `FeatureToggleDbName`. You can see an example datasource [here](#setting-up-a-datasource).
- Start the application
  `npm start`

### Asymmetric Token Signing and Verification

If you are using asymmetric token signing and verification, you should have auth datasource present in the service and auth redis datasource on the facade level. Example datasource file for auth database is:-

Auth DB datasource :-

```ts
import {inject, lifeCycleObserver, LifeCycleObserver} from '@loopback/core';
import {juggler} from '@loopback/repository';
import {AuthDbSourceName} from '@sourceloop/core';
const DEFAULT_MAX_CONNECTIONS = 25;
const DEFAULT_DB_IDLE_TIMEOUT_MILLIS = 60000;
const DEFAULT_DB_CONNECTION_TIMEOUT_MILLIS = 2000;

const config = {
  name: 'auth',
  connector: 'postgresql',
  host: process.env.DB_HOST,
  port: process.env.DB_PORT,
  user: process.env.DB_USER,
  schema: process.env.DB_SCHEMA,
  password: process.env.DB_PASSWORD,
  database: process.env.AUTH_DB,
};

// Observe application's life cycle to disconnect the datasource when
// application is stopped. This allows the application to be shut down
// gracefully. The `stop()` method is inherited from `juggler.DataSource`.
// Learn more at https://loopback.io/doc/en/lb4/Life-cycle.html
@lifeCycleObserver('datasource')
export class AuthDataSource
  extends juggler.DataSource
  implements LifeCycleObserver
{
  static dataSourceName = AuthDbSourceName;

  static readonly defaultConfig = config;

  constructor(
    @inject('datasources.config.auth', {optional: true})
    dsConfig: object = config,
  ) {
    if (!!+(process.env.ENABLE_DB_CONNECTION_POOLING ?? 0)) {
      const dbPool = {
        max: +(process.env.DB_MAX_CONNECTIONS ?? DEFAULT_MAX_CONNECTIONS),
        idleTimeoutMillis: +(
          process.env.DB_IDLE_TIMEOUT_MILLIS ?? DEFAULT_DB_IDLE_TIMEOUT_MILLIS
        ),
        connectionTimeoutMillis: +(
          process.env.DB_CONNECTION_TIMEOUT_MILLIS ??
          DEFAULT_DB_CONNECTION_TIMEOUT_MILLIS
        ),
      };

      dsConfig = {...dsConfig, ...dbPool};
    }

    super(dsConfig);
  }
}
```

Auth Cache Redis Datasource:-

```ts
import {inject, lifeCycleObserver, LifeCycleObserver} from '@loopback/core';
import {AnyObject, juggler} from '@loopback/repository';
import {readFileSync} from 'fs';
import {AuthCacheSourceName} from '@sourceloop/core';

const config = {
  name: process.env.REDIS_NAME,
  connector: 'kv-redis',
  host: process.env.REDIS_HOST,
  port: process.env.REDIS_PORT,
  password: process.env.REDIS_PASSWORD,
  db: process.env.REDIS_DATABASE,
  url: process.env.REDIS_URL,
  tls:
    +process.env.REDIS_TLS_ENABLED! && process.env.REDIS_TLS_CERT
      ? {
          ca: readFileSync(process.env.REDIS_TLS_CERT),
        }
      : undefined,
  sentinels:
    +process.env.REDIS_HAS_SENTINELS! && process.env.REDIS_SENTINELS
      ? JSON.parse(process.env.REDIS_SENTINELS)
      : undefined,
  sentinelPassword:
    +process.env.REDIS_HAS_SENTINELS! && process.env.REDIS_SENTINEL_PASSWORD
      ? process.env.REDIS_SENTINEL_PASSWORD
      : undefined,
  role:
    +process.env.REDIS_HAS_SENTINELS! && process.env.REDIS_SENTINEL_ROLE
      ? process.env.REDIS_SENTINEL_ROLE
      : undefined,
};

@lifeCycleObserver('datasource')
export class RedisDataSource
  extends juggler.DataSource
  implements LifeCycleObserver
{
  static readonly dataSourceName = AuthCacheSourceName;
  static readonly defaultConfig = config;

  constructor(
    @inject(`datasources.config.${process.env.REDIS_NAME}`, {optional: true})
    dsConfig: AnyObject = config,
  ) {
    if (
      +process.env.REDIS_HAS_SENTINELS! &&
      !!process.env.REDIS_SENTINEL_HOST &&
      !!process.env.REDIS_SENTINEL_PORT
    ) {
      dsConfig.sentinels = [
        {
          host: process.env.REDIS_SENTINEL_HOST,
          port: +process.env.REDIS_SENTINEL_PORT,
        },
      ];
    }
    super(dsConfig);
  }
}
```

### Environment Variables

| Name          | Required | Default Value | Description                                                                                                                        |
| ------------- | -------- | ------------- | ---------------------------------------------------------------------------------------------------------------------------------- |
| `NODE_ENV`    | Y        |               | Node environment value, i.e. `dev`, `test`, `prod`                                                                                 |
| `LOG_LEVEL`   | Y        |               | Log level value, i.e. `error`, `warn`, `info`, `verbose`, `debug`                                                                  |
| `DB_HOST`     | Y        |               | Hostname for the database server.                                                                                                  |
| `DB_PORT`     | Y        |               | Port for the database server.                                                                                                      |
| `DB_USER`     | Y        |               | User for the database.                                                                                                             |
| `DB_PASSWORD` | Y        |               | Password for the database user.                                                                                                    |
| `DB_DATABASE` | Y        |               | Database to connect to on the database server.                                                                                     |
| `DB_SCHEMA`   | Y        |               | Database schema used for the data source. In PostgreSQL, this will be `public` unless a schema is made explicitly for the service. |
| `JWT_SECRET`  | Y        |               | Symmetric signing key of the JWT token.                                                                                            |
| `JWT_ISSUER`  | Y        |               | Issuer of the JWT token.                                                                                                           |

### Setting up a `DataSource`

Here is a sample Implementation `DataSource` implementation using environment variables and PostgreSQL as the data source.

```typescript
import {inject, lifeCycleObserver, LifeCycleObserver} from '@loopback/core';
import {juggler} from '@loopback/repository';
import {FeatureToggleDbName} from '@sourceloop/feature-toggle-service';

const config = {
  name: FeatureToggleDbName,
  connector: 'postgresql',
  url: '',
  host: process.env.DB_HOST,
  port: process.env.DB_PORT,
  user: process.env.DB_USER,
  password: process.env.DB_PASSWORD,
  database: process.env.DB_DATABASE,
  schema: process.env.DB_SCHEMA,
};

@lifeCycleObserver('datasource')
export class FeatureToggleDbDataSource
  extends juggler.DataSource
  implements LifeCycleObserver
{
  static dataSourceName = FeatureToggleDbName;
  static readonly defaultConfig = config;

  constructor(
    @inject('datasources.config.feature', {optional: true})
    dsConfig: object = config,
  ) {
    super(dsConfig);
  }
}
```

### Migrations

The migrations required for this service are processed during the installation automatically if you set the `FEATURETOGGLE_MIGRATION` or `SOURCELOOP_MIGRATION` env variable. The migrations use [`db-migrate`](https://www.npmjs.com/package/db-migrate) with [`db-migrate-pg`](https://www.npmjs.com/package/db-migrate-pg) driver for migrations, so you will have to install these packages to use auto-migration. Please note that if you are using some pre-existing migrations or database, they may be effected. In such scenario, it is advised that you copy the migration files in your project root, using the `FEATURETOGGLE_MIGRATION_COPY` or `SOURCELOOP_MIGRATION_COPY` env variables. You can customize or cherry-pick the migrations in the copied files according to your specific requirements and then apply them to the DB.

This migration script supports both MySQL and PostgreSQL databases, controlled by environment variables. By setting MYSQL_MIGRATION to 'true', the script runs migrations using MySQL configuration files; otherwise, it defaults to PostgreSQL. .

Additionally, there is now an option to choose between SQL migration or PostgreSQL migration.
NOTE : For [`@sourceloop/cli`](https://www.npmjs.com/package/@sourceloop/cli?activeTab=readme) users, this choice can be specified during the scaffolding process by selecting the "type of datasource" option.

### API Documentation

#### Common Headers

Authorization: Bearer <token> where <token> is a JWT token signed using JWT issuer and secret.
`Content-Type: application/json` in the response and in request if the API method is NOT GET

#### Common Request path Parameters

{version}: Defines the API Version

### Common Responses

200: Successful Response. Response body varies w.r.t API
401: Unauthorized: The JWT token is missing or invalid
403: Forbidden : Not allowed to execute the concerned API
404: Entity Not Found
400: Bad Request (Error message varies w.r.t API)
201: No content: Empty Response

#### API Details

Visit the [OpenAPI spec docs](./openapi.md)