155 lines
4.3 KiB
JavaScript
155 lines
4.3 KiB
JavaScript
var fs = require('fs');
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var path = require('path');
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var ConfigLoader = exports;
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/**
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* Load application config from `app.json` and friends.
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* @param {String} rootDir Directory where to look for files.
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* @param {String} env Environment, usually `process.env.NODE_ENV`
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* @returns {Object}
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*/
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ConfigLoader.loadAppConfig = function(rootDir, env) {
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return loadNamed(rootDir, env, 'config', mergeAppConfig);
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};
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/**
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* Load data-sources config from `datasources.json` and friends.
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* @param {String} rootDir Directory where to look for files.
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* @param {String} env Environment, usually `process.env.NODE_ENV`
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* @returns {Object}
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*/
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ConfigLoader.loadDataSources = function(rootDir, env) {
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return loadNamed(rootDir, env, 'datasources', mergeDataSourceConfig);
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};
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/**
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* Load model config from `model-config.json` and friends.
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* @param {String} rootDir Directory where to look for files.
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* @param {String} env Environment, usually `process.env.NODE_ENV`
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* @returns {Object}
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*/
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ConfigLoader.loadModels = function(rootDir, env) {
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/*jshint unused:false */
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return tryReadJsonConfig(rootDir, 'model-config') || {};
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};
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/*-- Implementation --*/
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/**
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* Load named configuration.
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* @param {String} rootDir Directory where to look for files.
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* @param {String} env Environment, usually `process.env.NODE_ENV`
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* @param {String} name
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* @param {function(target:Object, config:Object, filename:String)} mergeFn
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* @returns {Object}
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*/
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function loadNamed(rootDir, env, name, mergeFn) {
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var files = findConfigFiles(rootDir, env, name);
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var configs = loadConfigFiles(files);
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return mergeConfigurations(configs, mergeFn);
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}
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/**
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* Search `appRootDir` for all files containing configuration for `name`.
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* @param {String} appRootDir
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* @param {String} env Environment, usually `process.env.NODE_ENV`
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* @param {String} name
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* @returns {Array.<String>} Array of absolute file paths.
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*/
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function findConfigFiles(appRootDir, env, name) {
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var master = ifExists(name + '.json');
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if (!master) return [];
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var candidates = [
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master,
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ifExistsWithAnyExt(name + '.local'),
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ifExistsWithAnyExt(name + '.' + env)
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];
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return candidates.filter(function(c) { return c !== undefined; });
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function ifExists(fileName) {
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var filepath = path.resolve(appRootDir, fileName);
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return fs.existsSync(filepath) ? filepath : undefined;
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}
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function ifExistsWithAnyExt(fileName) {
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return ifExists(fileName + '.js') || ifExists(fileName + '.json');
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}
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}
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/**
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* Load configuration files into an array of objects.
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* Attach non-enumerable `_filename` property to each object.
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* @param {Array.<String>} files
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* @returns {Array.<Object>}
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*/
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function loadConfigFiles(files) {
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return files.map(function(f) {
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var config = require(f);
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Object.defineProperty(config, '_filename', {
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enumerable: false,
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value: f
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});
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return config;
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});
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}
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/**
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* Merge multiple configuration objects into a single one.
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* @param {Array.<Object>} configObjects
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* @param {function(target:Object, config:Object, filename:String)} mergeFn
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*/
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function mergeConfigurations(configObjects, mergeFn) {
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var result = configObjects.shift() || {};
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while(configObjects.length) {
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var next = configObjects.shift();
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mergeFn(result, next, next._filename);
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}
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return result;
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}
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function mergeDataSourceConfig(target, config, fileName) {
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for (var ds in target) {
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var err = applyCustomConfig(target[ds], config[ds]);
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if (err) {
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throw new Error('Cannot apply ' + fileName + ' to `' + ds + '`: ' + err);
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}
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}
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}
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function mergeAppConfig(target, config, fileName) {
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var err = applyCustomConfig(target, config);
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if (err) {
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throw new Error('Cannot apply ' + fileName + ': ' + err);
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}
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}
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function applyCustomConfig(target, config) {
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for (var key in config) {
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var value = config[key];
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if (typeof value === 'object') {
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return 'override for the option `' + key + '` is not a value type.';
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}
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target[key] = value;
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}
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return null; // no error
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}
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/**
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* Try to read a config file with .json extension
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* @param cwd Dirname of the file
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* @param fileName Name of the file without extension
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* @returns {Object|undefined} Content of the file, undefined if not found.
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*/
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function tryReadJsonConfig(cwd, fileName) {
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try {
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return require(path.join(cwd, fileName + '.json'));
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} catch(e) {
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if(e.code !== 'MODULE_NOT_FOUND') {
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throw e;
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}
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}
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}
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