config.md

Configuration Module

Serves the purpose of allowing asynchronous secret population, it works along with *.config.ts files that contains the definition of injectable class.

Decorate a class with @Config() in order to mark it as a configuration definition. It will be available as a regular provider for NestJS injection.

Any property decorated with @InjectSecret() will have its value extracted from process.env and added to the class.

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Usage

Create a *.config.ts file declaring you configuration class with @Config() and decorate target properties with @InjectSecret():

import { Config, InjectSecret } from '@bechara/crux';

@Config()
export class FooConfig {

  @InjectSecret()
  FOO_API_URL: string;

  // Use 'key' if the env variable has
  // a different name than the property.
  @InjectSecret({ key: 'foo_authorization' })
  FOO_API_KEY: string;

  // Use 'fallback' to set a base value
  @InjectSecret({ fallback: 15 })
  FOO_API_MAX_CONCURRENCY: number;

}

The framework also allows decoration of properties using class-validator and class-transformer to enforce validation of the value before initialization:

import { Config, InjectSecret, IsUrl, IsString, Length, ToNumber } from '@bechara/crux';

@Config()
export class FooConfig {

  @InjectSecret()
  @IsUrl()
  FOO_API_URL: string;

  @InjectSecret({ key: 'foo_authorization' })
  @IsString() @Length(36)
  FOO_API_KEY: string;

  @InjectSecret({ fallback: '15' })
  @ToNumber()
  @IsNumber()
  FOO_API_MAX_CONCURRENCY: number;

}

Finally, to use the secrets, you must add the configuration class to the array of providers of your module and inject it into your service:

@Injectable()
export class FooService {

  public constructor(
    private readonly fooConfig: FooConfig,
  ) { }

  public async readFooById(id: number) {
    const maxConcurrency = this.fooConfig.FOO_API_MAX_CONCURRENCY;
    console.log(maxConcurrency);
  }
}

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