Ts-yaml-loader NPM

Description

Simple library to evaluate yaml files interpolating environment variables, validating and enforcing type safety.

Installation

$ npm i --save bruno-de-queiroz/ts-yaml-loader

Usage

# application.yaml
port: 3000

observability:
  version: ${npm_package_version:1.0.0}

swagger:
  title: Test api
  description: APIs available for integrations
  tags:
    - api

// main.ts
class ApplicationConfig {
  readonly port: string;
  readonly observability: { version: string };
  readonly swagger: {
    title: string;
    description: string;
    tags: string[];
  };
}

const config = load<ApplicationConfig>();

Usage with class-validator and class-transformer decorators and validations

// main
class ApplicationConfig {
  @IsNotEmpty()
  @IsNumber()
  readonly port: string;

  @ValidateNested()
  @Type(() => ObservabilityConfig)
  readonly observability: ObservabilityConfig;

  @ValidateNested()
  @Type(() => SwaggerConfig)
  readonly swagger: SwaggerConfig;
}

const config = load<ApplicationConfig>({
  validate: (value: ApplicationConfig) => {
    const errors = validateSync(plainToClass(ApplicationConfig, value));
    if (errors.length === 0) {
      return value;
    }

    throw new Error(errors.map((it) => it.toString()))
  },
});

Options and methods

interface ConfigOptions<T> {
  /**
   * The path of the property in the yaml file to be loaded
   */
  path?: string;
  /**
   * The file path for the yaml file to be loaded
   */
  file?: string;
  /**
   * The validation method that will be called to validate the data
   */
  validate?: (value: T) => T;
  /**
   * If true will remove the variables from process.env
   */
  strict?: boolean;
}

load<T>(config?: ConfigOptions) loads by default the application.yaml and uses expand to interpolate environment variables
expand(blob: string) interpolates environment variables in a string