| # cosmiconfig |
| |
| [](https://travis-ci.org/davidtheclark/cosmiconfig) [](https://ci.appveyor.com/project/davidtheclark/cosmiconfig/branch/main) |
| [](https://codecov.io/gh/davidtheclark/cosmiconfig) |
| |
| Cosmiconfig searches for and loads configuration for your program. |
| |
| It features smart defaults based on conventional expectations in the JavaScript ecosystem. |
| But it's also flexible enough to search wherever you'd like to search, and load whatever you'd like to load. |
| |
| By default, Cosmiconfig will start where you tell it to start and search up the directory tree for the following: |
| |
| - a `package.json` property |
| - a JSON or YAML, extensionless "rc file" |
| - an "rc file" with the extensions `.json`, `.yaml`, `.yml`, `.js`, or `.cjs` |
| - a `.config.js` or `.config.cjs` CommonJS module |
| |
| For example, if your module's name is "myapp", cosmiconfig will search up the directory tree for configuration in the following places: |
| |
| - a `myapp` property in `package.json` |
| - a `.myapprc` file in JSON or YAML format |
| - a `.myapprc.json`, `.myapprc.yaml`, `.myapprc.yml`, `.myapprc.js`, or `.myapprc.cjs` file |
| - a `myapp.config.js` or `myapp.config.cjs` CommonJS module exporting an object |
| |
| Cosmiconfig continues to search up the directory tree, checking each of these places in each directory, until it finds some acceptable configuration (or hits the home directory). |
| |
| ## Table of contents |
| |
| - [Installation](#installation) |
| - [Usage](#usage) |
| - [Result](#result) |
| - [Asynchronous API](#asynchronous-api) |
| - [cosmiconfig()](#cosmiconfig-1) |
| - [explorer.search()](#explorersearch) |
| - [explorer.load()](#explorerload) |
| - [explorer.clearLoadCache()](#explorerclearloadcache) |
| - [explorer.clearSearchCache()](#explorerclearsearchcache) |
| - [explorer.clearCaches()](#explorerclearcaches) |
| - [Synchronous API](#synchronous-api) |
| - [cosmiconfigSync()](#cosmiconfigsync) |
| - [explorerSync.search()](#explorersyncsearch) |
| - [explorerSync.load()](#explorersyncload) |
| - [explorerSync.clearLoadCache()](#explorersyncclearloadcache) |
| - [explorerSync.clearSearchCache()](#explorersyncclearsearchcache) |
| - [explorerSync.clearCaches()](#explorersyncclearcaches) |
| - [cosmiconfigOptions](#cosmiconfigoptions) |
| - [searchPlaces](#searchplaces) |
| - [loaders](#loaders) |
| - [packageProp](#packageprop) |
| - [stopDir](#stopdir) |
| - [cache](#cache) |
| - [transform](#transform) |
| - [ignoreEmptySearchPlaces](#ignoreemptysearchplaces) |
| - [Caching](#caching) |
| - [Differences from rc](#differences-from-rc) |
| - [Contributing & Development](#contributing--development) |
| |
| ## Installation |
| |
| ``` |
| npm install cosmiconfig |
| ``` |
| |
| Tested in Node 10+. |
| |
| ## Usage |
| |
| Create a Cosmiconfig explorer, then either `search` for or directly `load` a configuration file. |
| |
| ```js |
| const { cosmiconfig, cosmiconfigSync } = require('cosmiconfig'); |
| // ... |
| const explorer = cosmiconfig(moduleName); |
| |
| // Search for a configuration by walking up directories. |
| // See documentation for search, below. |
| explorer.search() |
| .then((result) => { |
| // result.config is the parsed configuration object. |
| // result.filepath is the path to the config file that was found. |
| // result.isEmpty is true if there was nothing to parse in the config file. |
| }) |
| .catch((error) => { |
| // Do something constructive. |
| }); |
| |
| // Load a configuration directly when you know where it should be. |
| // The result object is the same as for search. |
| // See documentation for load, below. |
| explorer.load(pathToConfig).then(..); |
| |
| // You can also search and load synchronously. |
| const explorerSync = cosmiconfigSync(moduleName); |
| |
| const searchedFor = explorerSync.search(); |
| const loaded = explorerSync.load(pathToConfig); |
| ``` |
| |
| ## Result |
| |
| The result object you get from `search` or `load` has the following properties: |
| |
| - **config:** The parsed configuration object. `undefined` if the file is empty. |
| - **filepath:** The path to the configuration file that was found. |
| - **isEmpty:** `true` if the configuration file is empty. This property will not be present if the configuration file is not empty. |
| |
| ## Asynchronous API |
| |
| ### cosmiconfig() |
| |
| ```js |
| const { cosmiconfig } = require('cosmiconfig'); |
| const explorer = cosmiconfig(moduleName[, cosmiconfigOptions]) |
| ``` |
| |
| Creates a cosmiconfig instance ("explorer") configured according to the arguments, and initializes its caches. |
| |
| #### moduleName |
| |
| Type: `string`. **Required.** |
| |
| Your module name. This is used to create the default [`searchPlaces`] and [`packageProp`]. |
| |
| If your [`searchPlaces`] value will include files, as it does by default (e.g. `${moduleName}rc`), your `moduleName` must consist of characters allowed in filenames. That means you should not copy scoped package names, such as `@my-org/my-package`, directly into `moduleName`. |
| |
| **[`cosmiconfigOptions`] are documented below.** |
| You may not need them, and should first read about the functions you'll use. |
| |
| ### explorer.search() |
| |
| ```js |
| explorer.search([searchFrom]).then(result => {..}) |
| ``` |
| |
| Searches for a configuration file. Returns a Promise that resolves with a [result] or with `null`, if no configuration file is found. |
| |
| You can do the same thing synchronously with [`explorerSync.search()`]. |
| |
| Let's say your module name is `goldengrahams` so you initialized with `const explorer = cosmiconfig('goldengrahams');`. |
| Here's how your default [`search()`] will work: |
| |
| - Starting from `process.cwd()` (or some other directory defined by the `searchFrom` argument to [`search()`]), look for configuration objects in the following places: |
| 1. A `goldengrahams` property in a `package.json` file. |
| 2. A `.goldengrahamsrc` file with JSON or YAML syntax. |
| 3. A `.goldengrahamsrc.json`, `.goldengrahamsrc.yaml`, `.goldengrahamsrc.yml`, `.goldengrahamsrc.js`, or `.goldengrahamsrc.cjs` file. |
| 4. A `goldengrahams.config.js` or `goldengrahams.config.cjs` CommonJS module exporting the object. |
| - If none of those searches reveal a configuration object, move up one directory level and try again. |
| So the search continues in `./`, `../`, `../../`, `../../../`, etc., checking the same places in each directory. |
| - Continue searching until arriving at your home directory (or some other directory defined by the cosmiconfig option [`stopDir`]). |
| - If at any point a parsable configuration is found, the [`search()`] Promise resolves with its [result] \(or, with [`explorerSync.search()`], the [result] is returned). |
| - If no configuration object is found, the [`search()`] Promise resolves with `null` (or, with [`explorerSync.search()`], `null` is returned). |
| - If a configuration object is found *but is malformed* (causing a parsing error), the [`search()`] Promise rejects with that error (so you should `.catch()` it). (Or, with [`explorerSync.search()`], the error is thrown.) |
| |
| **If you know exactly where your configuration file should be, you can use [`load()`], instead.** |
| |
| **The search process is highly customizable.** |
| Use the cosmiconfig options [`searchPlaces`] and [`loaders`] to precisely define where you want to look for configurations and how you want to load them. |
| |
| #### searchFrom |
| |
| Type: `string`. |
| Default: `process.cwd()`. |
| |
| A filename. |
| [`search()`] will start its search here. |
| |
| If the value is a directory, that's where the search starts. |
| If it's a file, the search starts in that file's directory. |
| |
| ### explorer.load() |
| |
| ```js |
| explorer.load(loadPath).then(result => {..}) |
| ``` |
| |
| Loads a configuration file. Returns a Promise that resolves with a [result] or rejects with an error (if the file does not exist or cannot be loaded). |
| |
| Use `load` if you already know where the configuration file is and you just need to load it. |
| |
| ```js |
| explorer.load('load/this/file.json'); // Tries to load load/this/file.json. |
| ``` |
| |
| If you load a `package.json` file, the result will be derived from whatever property is specified as your [`packageProp`]. |
| |
| You can do the same thing synchronously with [`explorerSync.load()`]. |
| |
| ### explorer.clearLoadCache() |
| |
| Clears the cache used in [`load()`]. |
| |
| ### explorer.clearSearchCache() |
| |
| Clears the cache used in [`search()`]. |
| |
| ### explorer.clearCaches() |
| |
| Performs both [`clearLoadCache()`] and [`clearSearchCache()`]. |
| |
| ## Synchronous API |
| |
| ### cosmiconfigSync() |
| |
| ```js |
| const { cosmiconfigSync } = require('cosmiconfig'); |
| const explorerSync = cosmiconfigSync(moduleName[, cosmiconfigOptions]) |
| ``` |
| |
| Creates a *synchronous* cosmiconfig instance ("explorerSync") configured according to the arguments, and initializes its caches. |
| |
| See [`cosmiconfig()`]. |
| |
| ### explorerSync.search() |
| |
| ```js |
| const result = explorerSync.search([searchFrom]); |
| ``` |
| |
| Synchronous version of [`explorer.search()`]. |
| |
| Returns a [result] or `null`. |
| |
| ### explorerSync.load() |
| |
| ```js |
| const result = explorerSync.load(loadPath); |
| ``` |
| |
| Synchronous version of [`explorer.load()`]. |
| |
| Returns a [result]. |
| |
| ### explorerSync.clearLoadCache() |
| |
| Clears the cache used in [`load()`]. |
| |
| ### explorerSync.clearSearchCache() |
| |
| Clears the cache used in [`search()`]. |
| |
| ### explorerSync.clearCaches() |
| |
| Performs both [`clearLoadCache()`] and [`clearSearchCache()`]. |
| |
| ## cosmiconfigOptions |
| |
| Type: `Object`. |
| |
| Possible options are documented below. |
| |
| ### searchPlaces |
| |
| Type: `Array<string>`. |
| Default: See below. |
| |
| An array of places that [`search()`] will check in each directory as it moves up the directory tree. |
| Each place is relative to the directory being searched, and the places are checked in the specified order. |
| |
| **Default `searchPlaces`:** |
| |
| ```js |
| [ |
| 'package.json', |
| `.${moduleName}rc`, |
| `.${moduleName}rc.json`, |
| `.${moduleName}rc.yaml`, |
| `.${moduleName}rc.yml`, |
| `.${moduleName}rc.js`, |
| `.${moduleName}rc.cjs`, |
| `${moduleName}.config.js`, |
| `${moduleName}.config.cjs`, |
| ] |
| ``` |
| |
| Create your own array to search more, fewer, or altogether different places. |
| |
| Every item in `searchPlaces` needs to have a loader in [`loaders`] that corresponds to its extension. |
| (Common extensions are covered by default loaders.) |
| Read more about [`loaders`] below. |
| |
| `package.json` is a special value: When it is included in `searchPlaces`, Cosmiconfig will always parse it as JSON and load a property within it, not the whole file. |
| That property is defined with the [`packageProp`] option, and defaults to your module name. |
| |
| Examples, with a module named `porgy`: |
| |
| ```js |
| // Disallow extensions on rc files: |
| [ |
| 'package.json', |
| '.porgyrc', |
| 'porgy.config.js' |
| ] |
| |
| // ESLint searches for configuration in these places: |
| [ |
| '.eslintrc.js', |
| '.eslintrc.yaml', |
| '.eslintrc.yml', |
| '.eslintrc.json', |
| '.eslintrc', |
| 'package.json' |
| ] |
| |
| // Babel looks in fewer places: |
| [ |
| 'package.json', |
| '.babelrc' |
| ] |
| |
| // Maybe you want to look for a wide variety of JS flavors: |
| [ |
| 'porgy.config.js', |
| 'porgy.config.mjs', |
| 'porgy.config.ts', |
| 'porgy.config.coffee' |
| ] |
| // ^^ You will need to designate custom loaders to tell |
| // Cosmiconfig how to handle these special JS flavors. |
| |
| // Look within a .config/ subdirectory of every searched directory: |
| [ |
| 'package.json', |
| '.porgyrc', |
| '.config/.porgyrc', |
| '.porgyrc.json', |
| '.config/.porgyrc.json' |
| ] |
| ``` |
| |
| ### loaders |
| |
| Type: `Object`. |
| Default: See below. |
| |
| An object that maps extensions to the loader functions responsible for loading and parsing files with those extensions. |
| |
| Cosmiconfig exposes its default loaders on a named export `defaultLoaders`. |
| |
| **Default `loaders`:** |
| |
| ```js |
| const { defaultLoaders } = require('cosmiconfig'); |
| |
| console.log(Object.entries(defaultLoaders)) |
| // [ |
| // [ '.cjs', [Function: loadJs] ], |
| // [ '.js', [Function: loadJs] ], |
| // [ '.json', [Function: loadJson] ], |
| // [ '.yaml', [Function: loadYaml] ], |
| // [ '.yml', [Function: loadYaml] ], |
| // [ 'noExt', [Function: loadYaml] ] |
| // ] |
| ``` |
| |
| (YAML is a superset of JSON; which means YAML parsers can parse JSON; which is how extensionless files can be either YAML *or* JSON with only one parser.) |
| |
| **If you provide a `loaders` object, your object will be *merged* with the defaults.** |
| So you can override one or two without having to override them all. |
| |
| **Keys in `loaders`** are extensions (starting with a period), or `noExt` to specify the loader for files *without* extensions, like `.myapprc`. |
| |
| **Values in `loaders`** are a loader function (described below) whose values are loader functions. |
| |
| **The most common use case for custom loaders value is to load extensionless `rc` files as strict JSON**, instead of JSON *or* YAML (the default). |
| To accomplish that, provide the following `loaders` value: |
| |
| ```js |
| { |
| noExt: defaultLoaders['.json'] |
| } |
| ``` |
| |
| If you want to load files that are not handled by the loader functions Cosmiconfig exposes, you can write a custom loader function or use one from NPM if it exists. |
| |
| **Third-party loaders:** |
| |
| - [@endemolshinegroup/cosmiconfig-typescript-loader](https://github.com/EndemolShineGroup/cosmiconfig-typescript-loader) |
| |
| **Use cases for custom loader function:** |
| |
| - Allow configuration syntaxes that aren't handled by Cosmiconfig's defaults, like JSON5, INI, or XML. |
| - Allow ES2015 modules from `.mjs` configuration files. |
| - Parse JS files with Babel before deriving the configuration. |
| |
| **Custom loader functions** have the following signature: |
| |
| ```js |
| // Sync |
| (filepath: string, content: string) => Object | null |
| |
| // Async |
| (filepath: string, content: string) => Object | null | Promise<Object | null> |
| ``` |
| |
| Cosmiconfig reads the file when it checks whether the file exists, so it will provide you with both the file's path and its content. |
| Do whatever you need to, and return either a configuration object or `null` (or, for async-only loaders, a Promise that resolves with one of those). |
| `null` indicates that no real configuration was found and the search should continue. |
| |
| A few things to note: |
| |
| - If you use a custom loader, be aware of whether it's sync or async: you cannot use async customer loaders with the sync API ([`cosmiconfigSync()`]). |
| - **Special JS syntax can also be handled by using a `require` hook**, because `defaultLoaders['.js']` just uses `require`. |
| Whether you use custom loaders or a `require` hook is up to you. |
| |
| Examples: |
| |
| ```js |
| // Allow JSON5 syntax: |
| { |
| '.json': json5Loader |
| } |
| |
| // Allow a special configuration syntax of your own creation: |
| { |
| '.special': specialLoader |
| } |
| |
| // Allow many flavors of JS, using custom loaders: |
| { |
| '.mjs': esmLoader, |
| '.ts': typeScriptLoader, |
| '.coffee': coffeeScriptLoader |
| } |
| |
| // Allow many flavors of JS but rely on require hooks: |
| { |
| '.mjs': defaultLoaders['.js'], |
| '.ts': defaultLoaders['.js'], |
| '.coffee': defaultLoaders['.js'] |
| } |
| ``` |
| |
| ### packageProp |
| |
| Type: `string | Array<string>`. |
| Default: `` `${moduleName}` ``. |
| |
| Name of the property in `package.json` to look for. |
| |
| Use a period-delimited string or an array of strings to describe a path to nested properties. |
| |
| For example, the value `'configs.myPackage'` or `['configs', 'myPackage']` will get you the `"myPackage"` value in a `package.json` like this: |
| |
| ```json |
| { |
| "configs": { |
| "myPackage": {..} |
| } |
| } |
| ``` |
| |
| If nested property names within the path include periods, you need to use an array of strings. For example, the value `['configs', 'foo.bar', 'baz']` will get you the `"baz"` value in a `package.json` like this: |
| |
| ```json |
| { |
| "configs": { |
| "foo.bar": { |
| "baz": {..} |
| } |
| } |
| } |
| ``` |
| |
| If a string includes period but corresponds to a top-level property name, it will not be interpreted as a period-delimited path. For example, the value `'one.two'` will get you the `"three"` value in a `package.json` like this: |
| |
| ```json |
| { |
| "one.two": "three", |
| "one": { |
| "two": "four" |
| } |
| } |
| ``` |
| |
| ### stopDir |
| |
| Type: `string`. |
| Default: Absolute path to your home directory. |
| |
| Directory where the search will stop. |
| |
| ### cache |
| |
| Type: `boolean`. |
| Default: `true`. |
| |
| If `false`, no caches will be used. |
| Read more about ["Caching"](#caching) below. |
| |
| ### transform |
| |
| Type: `(Result) => Promise<Result> | Result`. |
| |
| A function that transforms the parsed configuration. Receives the [result]. |
| |
| If using [`search()`] or [`load()`] \(which are async), the transform function can return the transformed result or return a Promise that resolves with the transformed result. |
| If using `cosmiconfigSync`, [`search()`] or [`load()`], the function must be synchronous and return the transformed result. |
| |
| The reason you might use this option — instead of simply applying your transform function some other way — is that *the transformed result will be cached*. If your transformation involves additional filesystem I/O or other potentially slow processing, you can use this option to avoid repeating those steps every time a given configuration is searched or loaded. |
| |
| ### ignoreEmptySearchPlaces |
| |
| Type: `boolean`. |
| Default: `true`. |
| |
| By default, if [`search()`] encounters an empty file (containing nothing but whitespace) in one of the [`searchPlaces`], it will ignore the empty file and move on. |
| If you'd like to load empty configuration files, instead, set this option to `false`. |
| |
| Why might you want to load empty configuration files? |
| If you want to throw an error, or if an empty configuration file means something to your program. |
| |
| ## Caching |
| |
| As of v2, cosmiconfig uses caching to reduce the need for repetitious reading of the filesystem or expensive transforms. Every new cosmiconfig instance (created with `cosmiconfig()`) has its own caches. |
| |
| To avoid or work around caching, you can do the following: |
| |
| - Set the `cosmiconfig` option [`cache`] to `false`. |
| - Use the cache-clearing methods [`clearLoadCache()`], [`clearSearchCache()`], and [`clearCaches()`]. |
| - Create separate instances of cosmiconfig (separate "explorers"). |
| |
| ## Differences from [rc](https://github.com/dominictarr/rc) |
| |
| [rc](https://github.com/dominictarr/rc) serves its focused purpose well. cosmiconfig differs in a few key ways — making it more useful for some projects, less useful for others: |
| |
| - Looks for configuration in some different places: in a `package.json` property, an rc file, a `.config.js` file, and rc files with extensions. |
| - Built-in support for JSON, YAML, and CommonJS formats. |
| - Stops at the first configuration found, instead of finding all that can be found up the directory tree and merging them automatically. |
| - Options. |
| - Asynchronous by default (though can be run synchronously). |
| |
| ## Contributing & Development |
| |
| Please note that this project is released with a [Contributor Code of Conduct](CODE_OF_CONDUCT.md). By participating in this project you agree to abide by its terms. |
| |
| And please do participate! |
| |
| [result]: #result |
| |
| [`load()`]: #explorerload |
| |
| [`search()`]: #explorersearch |
| |
| [`clearloadcache()`]: #explorerclearloadcache |
| |
| [`clearsearchcache()`]: #explorerclearsearchcache |
| |
| [`cosmiconfig()`]: #cosmiconfig |
| |
| [`cosmiconfigSync()`]: #cosmiconfigsync |
| |
| [`clearcaches()`]: #explorerclearcaches |
| |
| [`packageprop`]: #packageprop |
| |
| [`cache`]: #cache |
| |
| [`stopdir`]: #stopdir |
| |
| [`searchplaces`]: #searchplaces |
| |
| [`loaders`]: #loaders |
| |
| [`cosmiconfigoptions`]: #cosmiconfigoptions |
| |
| [`explorerSync.search()`]: #explorersyncsearch |
| |
| [`explorerSync.load()`]: #explorersyncload |
| |
| [`explorer.search()`]: #explorersearch |
| |
| [`explorer.load()`]: #explorerload |