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Version: 1.x


In FoalTS, configuration refers to any parameter that may vary between deploy environments (production, development, test, etc). It includes sensitive information, such as your database credentials, or simple settings, such as the server port.

The framework encourages a strict separation between configuration and code and allows you to define your configuration in environment variables, in an .env file or in files in the config/ directory. You can choose one of these techniques or use them all simultaneously.

Config directory structure

|- config/
| |- e2e.json
| |- default.json
| |- development.json
| |- production.json
| |- ...
| '- test.json
|- src/
'- .env

Architecture of a Configuration File

Example of .env file


Example of a file in the config/ directory

Both formats, JSON and YAML, are supported. Choose the one that suits you the best.

{% code-tabs %} {% code-tabs-item title="JSON" %}

"port": 3001,
"settings": {
"csrf": false,
"debug": false,
"loggerFormat": "tiny",
"staticPath": "public/",
"session": {
"cookie": {
"path": "/"
"secret": "my-secret"
"database": {
"database": "./db.sqlite3"

{% endcode-tabs-item %} {% code-tabs-item title="YAML" %}

port: 3001

csrf: false
debug: false
loggerFormat: tiny
staticPath: public/
path: /
secret: my-secret

database: './db.sqlite3'

{% endcode-tabs-item %} {% endcode-tabs %}

YAML support

The use of YAML for configuration requires the installation of the package yamljs.

npm install yamljs

When creating a new project, you can also add the flag --yaml to have all the configuration directly generated in YAML.

foal createapp my-app --yaml

The extension of the YAML files must be .yml.

Accessing Configuration Values

The Config class provides two static methods for accessing configuration values: get2 and getOrThrow. Use of Config.get is also possible, but is deprecated.

The Config.get2 method

Available since v1.7

This function takes the configuration key as parameter.

import { Config } from '@foal/core';

const secret = Config.get2('settings.jwt.secretOrPublicKey');

In this example, FoalTS will try to retrieve the configuration value via:

  • the environment variable SETTINGS_JWT_SECRET_OR_PUBLIC_KEY,
  • the .env file with the variable SETTINGS_JWT_SECRET_OR_PUBLIC_KEY,
  • the JSON file config/development.json with the path settings.jwt.secretOrPublicKey,
  • the YAML file config/development.yml with the path settings.jwt.secretOrPublicKey,
  • the JSON file config/default.json with the path settings.jwt.secretOrPublicKey,
  • or the YAML file config/default.yml with the path settings.jwt.secretOrPublicKey.

If no value is found, the method returns undefined.

If the NODE_ENV environment variable is set, Foal will look at ${NODE_ENV}.json (resp. ${NODE_ENV}.yml) instead of development.json (resp. development.yml).

Specifying a type

import { Config } from '@foal/core';

const foobar = Config.get2('settings.foobar', 'boolean|string');
// foobar is of type boolean|string|undefined

The method also accepts a second optional parameter to define the type of the returned value. When it is set, Foal checks that the configuration value has the correct type and if it does not, it throws a ConfigTypeError. In case the value is provided via an environment variable or the .env file, the method will try to convert it to the desired type (e.g. "true" becomes true). If it does not succeed, a ConfigTypeError is also thrown.

Allowed types

Specifying a default value

The third optional parameter of the method allows you to define a default value if none is found in the configuration.

const foobar = Config.get2('settings.foobar', 'boolean', false);
// foobar is of type boolean

The Config.getOrThrow method

Available since v1.7

const foobar = Config.getOrThrow('settings.foobar', 'boolean');
// foobar is of type boolean

This method has the same behavior as Config.get2 except that it does not accept a default value. If no value is found in the configuration files or in an environment variable, the method will throw a ConfigNotFoundError.

The deprecated Config.get method

Deprecated since v1.7

import { Config } from '@foal/core';

const debug = Config.get('settings.debug');

Type coercion and type variable

You can force the TypeScript type returned by the variable this way:

const debug = Config.get<boolean>('settings.debug');

But this is considered unsafe because the method does not check whether the returned value is of the desired type.

The method always attempts to convert values to a boolean or a number, regardless of the TypeScript type provided.. The value "36" will always be returned as 36.

Specifying a default value

A default variable can be provided as second argument of the method.

const debug = Config.get('settings.debug', false);

Configuration & FoalTS Components

As mentioned before, FoalTS encourages a strict separation between configuration and code. This is why most FoalTS components (services, controller, hooks) retreive their configuration directly from the config files or environment variables. They use the namespace settings for this purpose.

For example, FoalTS uses the configuration key settings.debug to determine if error tracebacks should be returned in the INTERNAL SERVER ERROR responses.

You should not create new configuration keys in the settings namespace as this may conflict with future versions of the framework.

default.yml (default)

port: 3001

// You should not define your own configuration keys in this section.
// Use only those specified in the documentation.
debug: true

// Custom configuration
config1: 'foobar'

// Custom configuration
age: 32

Precedence of the Configuration

Configuration specified in the .env file overrides the one defined in the config/ directory files. And configuration specified in environment variables overrides the one defined in the .env file.

Use case

PaaS providers often require that web applications be served on a specific port (8080, 80, etc.) that may be different from the one you use locally. Usually, the value of this port is specified in an environment variable named PORT. With FoalTS configuration system, the port is automatically replaced when your project is deployed and the application works as expected.

The config/ directory files also have a precedence system inside the directory. If your node environment is production (defined with the environment variable NODE_ENV), then the production.json file (if it exists) overrides the file default.json.

Database Configuration (TypeORM)

TypeORM uses a different system for its configuration based on the file ormconfig.js located at the root of the project directory.

You can however customize the ormconfig.js file to make it work with FoalTS configuration system.

ormconfig.js (example)

const { Config } = require('@foal/core');

module.exports = {
type: 'sqlite',
database: Config.get('database.database'),
dropSchema: Config.get('database.dropSchema', false),
entities: ["build/app/**/*.entity.js"],
migrations: ["build/migrations/*.js"],
cli: {
migrationsDir: "src/migrations"
synchronize: Config.get('database.synchronize', false)

default.yml (example)

port: 3001


database: './db.sqlite3'

test.yml (example)

database: './test_db.sqlite3'
dropSchema: true
synchronize: true


Using Config as a Service

In order to mock the configuration during the tests, you can also use Config as a service. This is particularly useful for testing reusable components (hook, service) whose behavior varies according to the configuration.

app.controller.ts (example)

import { Config, dependency, Get } from '@foal/core';

export class AppController {
config: Config;

get() {
const debug = this.config.get<boolean>('debug');
// Do something.


app.controller.spec.ts (example)

import { createController, ConfigMock } from '@foal/core';

import { AppController } from './app.controller';

describe('AppController', () => {

let config: ConfigMock;
let controller: AppController;

before(() => {
config = new ConfigMock();
controller = createController(AppController, { config });

beforeEach(() => config.reset());

it('should do something (debug=true).', () => {
config.set(debug, true);
// ...

it('should do another something (debug=false).', () => {
config.set(debug, false);
// ...