examples/hello-egg/config/config.default.ts

import {EggAppConfig, EggAppInfo, PowerPartial} from 'egg';

// for config.{env}.ts
export type DefaultConfig = PowerPartial<EggAppConfig & BizConfig>;

// app special config scheme
export interface BizConfig {
  sourceUrl: string;
}

export default (appInfo: EggAppInfo) => {
  const config = {} as PowerPartial<EggAppConfig> & BizConfig;

  // override config from framework / plugin
  // use for cookie sign key, should change to your own and keep security
  config.keys = appInfo.name + '_1528804995511_9134';

  // add your config here
  config.middleware = [];

  return config;
};