ask-cli/lib/model/yaml-parser.js

/**
 * YAML load and dump from/to JSON object.
 * Support the loading of AWS Cloudformation intrinsinc function:
 * https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference.html
 */

const fs = require('fs');
const yaml = require('js-yaml');

// Custom type for "!Ref"
const refYamlType = new yaml.Type('!Ref', {
    kind: 'scalar',
    resolve: data => !!data && typeof data === 'string' && data.trim(),
    construct: data => `!Ref ${data}`
});

// Custom type for "!GetAtt"
const getattYamlType = new yaml.Type('!GetAtt', {
    kind: 'scalar',
    resolve: data => !!data && typeof data === 'string' && data.trim(),
    construct: data => `!GetAtt ${data}`
});

// Create AWS schema for YAML parser
const awsSchema = yaml.Schema.create(yaml.JSON_SCHEMA, [refYamlType, getattYamlType]);

/**
 * Load the yaml file with aws's schema
 * @param {String} filePath File path for the yaml file
 */
function load(filePath) {
    const fileData = fs.readFileSync(filePath, 'utf-8');
    return yaml.safeLoad(fileData, { schema: awsSchema });
}

/**
 * Dump the yaml file by merge the new content to the original file
 * @param {String} filePath File path for the yaml file
 * @param {Object} content Content to be written into filePath
 */
function dump(filePath, content) {
    fs.writeFileSync(filePath, yaml.dump(content).replace(/: *'(.+)'/g, ': $1')); // remove the single quotes for the value
}

module.exports = {
    load,
    dump
};