How to use git-rev

gitRev.tag((tag) => {
  gitData.tag = tag;
  resolve(tag);
 });

// First, add the current git release to the config
git.tag(apiVer => {
 const semver = require('semver');
 apiVer = semver.valid(apiVer);
 if (!apiVer) {
  // This is probably an NPM install - get version from package.json
  const pkg = require('./package.json');
  apiVer = semver.valid(pkg.version);
 }
 nconf.set('env:APP_VERSION', apiVer || 'unknown');
 logger.debug(`timings API - CONFIG - Following settings are in use: \n${JSON.stringify(nconf.get(), null, 2)}`);
 logger.info(`timings API - CONFIG - Using config ["${nconf.get('env:APP_CONFIG') || '{unknown}'}"]`);
 logger.info(`timings API - STATUS - Server v${nconf.get('env:APP_VERSION') || '{unknown}'} is running at ` +
  `http://${nconf.get('env:HOST')}:${nconf.get('env:HTTP_PORT')}`);

 // Check ES (if in use)
 if (nconf.get('env:ES_HOST')) {
  const runES = require('./src/run-es');
  const checkES = new runES.Elastic();
  checkES.setup();
 } else {
  logger.warn(`timings API - CONFIG - No Elasticsearch HOST in config [${nconf.get('env:APP_CONFIG')}] - data will NOT be saved!`);
 }
 startListen();
});

gitRev.branch((branch) => {
  gitData.branch = branch;
  resolve(branch);
 });

gitRev.long((longVersion) => {
  gitData.long = longVersion;
  resolve(longVersion);
 });

gitRev.short((short) => {
  gitData.short = short;
  resolve(short);
 });