Create gzipped tarballs in nodejs with correct owners & permissions.

node-tgz-permissions.js

//NOTE: the source permissions need to be set appropriately, also.
// npm i --save targz

const targz = require('targz')

targz.compress({
  src: '/tmp/mydirectory',
  dest: 'output/filename.tgz',
  tar: {
    dmode: 0775,  // Directories: rwxrwxr-x
    fmode: 0664,  // Files: rw-rw-r--
    umask: 0002,  // Sets umask (default perm) for newly created files
    map: function(header) {
      header.name = './'+header.name // Add './' prefix
      header.uname = 'user'
      header.gname = 'group'
      return header
    }
  }
})