Custom grain based on hostname

myenv.py

# _grains/myenv.py

import sys
import socket
import re
import platform

# Extend the default list of supported distros. This will be used for the
# /etc/DISTRO-release checking that is part of platform.linux_distribution()
from platform import _supported_dists
_supported_dists += ('arch', 'mageia', 'meego', 'vmware', 'bluewhite64',
                     'slamd64', 'enterprise', 'ovs', 'system')

import salt.utils

# Solve the Chicken and egg problem where grains need to run before any
# of the modules are loaded and are generally available for any usage.
import salt.modules.cmdmod
__salt__ = {
    'cmd.run': salt.modules.cmdmod._run_quiet,
}

def myenv():
  grains = {}
  hostname = socket.gethohostname()
  if re.match('web', hostname):
    grains['myenv'] = 'production'
  elif ...
  ...

  return grains