The following files are looked up and merged (the latest take precedence):

1. vendor: config.* in the application directory;
2. global: /etc/my-application/config.*;
3. user: ~/.config/my-application/config.*;
4. local: /.my-application.* down to ./.my-application.* in the current working directory;

Note: the local config is relative to the current working directory and only makes sense for CLIs.

var loadConfig = require("app-conf").load;

loadConfig("my-application", {
  // this is the directory where the vendor conf is stored
  //
  // vendor config will not be loaded if not defined
  appDir: __dirname,

  // equivalent of `__dirname` for ECMAScript Modules:
  //appDir: new URL('.', import.meta.url).pathname,

  // default config values
  defaults: {},

  // which types of config should be loaded
  entries: ["vendor", "global", "user", "local"],

  // whether to ignore unknown file formats instead of throwing
  ignoreUnknownFormats: false,
}).then(function (config) {
  console.log(config);
});

Relative paths, string values starting by ./ or ../, are automatically resolved from the config file directory.

Paths relative to the home directory, string values starting by ~/, are also automatically resolved.

JSON format is supported natively but you may install the following packages to have additional features:

• @iarna/toml: to support TOML files;
• cson-parse: to support CSON files;
• ini: to support INI files;
• js-yaml: to support YAML files;
• json5: to support advanced JSON files;
• strip-json-comments: to support comments in JSON files.

This method reload the configuration every time it might have changed.

const watchConfig = require("app-conf").watch;

const stopWatching = await watchConfig(
  {
    // contrary to `load`, this is part of the options
    appName: "my-application",

    // if set to true the configuration will be loaded before waiting for
    // changes
    //
    // in that case, the returned promise will reject if the initial load
    // failed, or will resolve after the callback has been called with the
    // initial configuration
    //
    // because the async call to `watchConfig()` will not have returned yet,
    // `stopWatching()` will not be available in this first callback call
    initialLoad: false,

    // all other options are passed to load()
  },
  (error, config) => {
    if (error !== undefined) {
      console.warn("loading config has failed");

      // we might not want to retry on changes
      stopWatching();

      return;
    }

    console.log("config has been loaded", config);
  },
);

Note: the vendor config IS NOT watched, but it's loaded as expected.

A basic CLI is available to show the config:

> ./node_modules/.bin/app-conf
Usage: app-conf [--json | -j] [--watch | -w] [-p <path>]... <appName> [<appDir>]

app-conf v2.2.1
> ./node_modules/.bin/app-conf my-app .

Note: To ensure the configuration is parsed the same way as your application (e.g. optional formats), this command should be run from your application directory and not from a global install.

Contributions are very welcome, either on the documentation or on the code.

You may:

• report any issue you've encountered;
• fork and create a pull request.

ISC © Julien Fontanet