@redocly/openapi-core/src/config/load.ts

See https://github.com/Redocly/openapi-cli

import * as fs from 'fs';
import * as path from 'path';
import { RedoclyClient } from '../redocly';
import { loadYaml } from '../utils';
import { Config, DOMAINS, RawConfig, Region, transformConfig } from './config';
import { defaultPlugin } from './builtIn';

export async function loadConfig(configPath: string | undefined = findConfig(), customExtends?: string[]): Promise<Config> {
  const rawConfig = await getConfig(configPath);

  if (customExtends !== undefined) {
    rawConfig.lint = rawConfig.lint || {};
    rawConfig.lint.extends = customExtends;
  }

  const redoclyClient = new RedoclyClient();
  const tokens = await redoclyClient.getTokens();

  if (tokens.length) {
    if (!rawConfig.resolve) rawConfig.resolve = {};
    if (!rawConfig.resolve.http) rawConfig.resolve.http = {};
    rawConfig.resolve.http.headers = [...(rawConfig.resolve.http.headers ?? [])];

    for (const item of tokens) {
      const domain = DOMAINS[item.region as Region];
      rawConfig.resolve.http.headers.push({
        matches: `https://api.${domain}/registry/**`,
        name: 'Authorization',
        envVariable: undefined,
        value: item.token,
      },
      //support redocly.com domain for future compatibility
      ...(item.region === 'us' ? [{
        matches: `https://api.redoc.ly/registry/**`,
        name: 'Authorization',
        envVariable: undefined,
        value: item.token,
      }] : []));
    }
  }
  return new Config(
    {
      ...rawConfig,
      lint: {
        ...rawConfig?.lint,
        plugins: [...(rawConfig?.lint?.plugins || []), defaultPlugin], // inject default plugin
      },
    },
    configPath,
  );
}

export const CONFIG_FILE_NAMES = ['redocly.yaml', 'redocly.yml', '.redocly.yaml', '.redocly.yml'];

export function findConfig(dir?: string): string | undefined {
  if (!fs.hasOwnProperty('existsSync')) return;
  const existingConfigFiles = CONFIG_FILE_NAMES
    .map(name => dir ? path.resolve(dir, name) : name)
    .filter(fs.existsSync);
  if (existingConfigFiles.length > 1) {
    throw new Error(`
      Multiple configuration files are not allowed. 
      Found the following files: ${existingConfigFiles.join(', ')}. 
      Please use 'redocly.yaml' instead.
    `);
  }
  return existingConfigFiles[0];
}

export async function getConfig(configPath: string | undefined = findConfig()) {
  if (!configPath) return {};
  try {
    const rawConfig = ((await loadYaml(configPath)) || {}) as RawConfig;
    return transformConfig(rawConfig);
  } catch (e) {
    throw new Error(`Error parsing config file at '${configPath}': ${e.message}`);
  }
}