@cap-js-community/feature-toggle-library/src/shared/cf-env.js

SAP BTP feature toggle library enables Node.js applications using the SAP Cloud Application Programming Model to maintain live-updatable feature toggles via Redis.

"use strict";

const pathlib = require("path");
const fs = require("fs");

const ENV = Object.freeze({
  USER: "USER",
  CF_APP: "VCAP_APPLICATION",
  CF_SERVICES: "VCAP_SERVICES",
  CF_INSTANCE_GUID: "CF_INSTANCE_GUID",
  CF_INSTANCE_IP: "CF_INSTANCE_IP",
  CF_INSTANCE_INDEX: "CF_INSTANCE_INDEX",
});

/**
 * CfEnv is a singleton class to interact with the Cloud Foundry environment variables.
 */
class CfEnv {
  static __instance;

  static parseEnvVar(env, envVar) {
    try {
      if (Object.prototype.hasOwnProperty.call(env, envVar)) {
        return JSON.parse(process.env[envVar]);
      }
    } catch (err) {} // eslint-disable-line no-empty
  }

  static readDefaultEnv() {
    try {
      const defaultEnvRaw = fs.readFileSync(pathlib.resolve(process.cwd(), "default-env.json"), "utf8");
      return Object.entries(JSON.parse(defaultEnvRaw)).reduce((acc, [key, value]) => {
        if (value !== null) {
          acc[key] = JSON.stringify(value);
        }
        return acc;
      }, {});
    } catch (err) {} // eslint-disable-line no-empty
  }

  constructor(inputEnv = process.env) {
    const env =
      inputEnv.NODE_ENV === "production"
        ? inputEnv
        : {
            ...CfEnv.readDefaultEnv(),
            ...inputEnv,
          };

    this.isOnCf = env[ENV.USER] === "vcap";
    this.cfApp = CfEnv.parseEnvVar(env, ENV.CF_APP) || {};
    this.cfServices = CfEnv.parseEnvVar(env, ENV.CF_SERVICES) || {};
    this.cfInstanceGuid = env[ENV.CF_INSTANCE_GUID];
    this.cfInstanceIp = env[ENV.CF_INSTANCE_IP];
    this.cfInstanceIndex = env[ENV.CF_INSTANCE_INDEX] ? parseInt(env[ENV.CF_INSTANCE_INDEX]) : undefined;
    this.__cfServiceList = [].concat(...Object.values(this.cfServices));
    this.__cfServiceLabelMap = this.__cfServiceList.reduce((result, service) => {
      if (service.label && !result[service.label]) {
        result[service.label] = service;
      }
      return result;
    }, {});
  }

  /**
   * @returns {CfEnv}
   */
  static getInstance() {
    if (!CfEnv.__instance) {
      CfEnv.__instance = new CfEnv();
    }
    return CfEnv.__instance;
  }

  cfServiceCredentials(options) {
    const service = this.__cfServiceList.find((service) =>
      Object.entries(options).reduce((result, [key, value]) => result && service[key] === value, true)
    );
    return service && service.credentials ? service.credentials : {};
  }

  cfServiceCredentialsForLabel(label) {
    const service = this.__cfServiceLabelMap[label];
    return service && service.credentials ? service.credentials : {};
  }
}

module.exports = {
  ENV,
  CfEnv,
};