ansible/library/authorized_key

#!/usr/bin/env python
"""Ansible module to add authorized_keys for ssh logins.

(c) 2012, Brad Olson <brado@movedbylight.com>

Results: Makes sure the public key line is present or absent in the user's .ssh/authorized_keys.

Arguments
=========
    user = username
    key = line to add to authorized_keys for user
    state = absent|present (default: present)

Command Line Example 
====================

ansible somehost -m authorized_key -a user=charlie key="ssh-dss AAAABUfOL+8BTwaRYr/rycsBF1D8e5pTxEsXHQs4iq+mZdyWqlW++L6pMiam1A8yweP+rKtgjK2httVS6GigVsuWWfOd7/sdWippefq74nppVUELHPKkaIOjJNN1zUHFoL/YMwAAAEBALnAsQN10TNGsRDe5arBsW8cTOjqLyYBcIqgPYTZW8zENErFxt7ij3fW3Jh/sCpnmy8rkS7FyK8ULX0PEy/2yDx8/5rXgMIICbRH/XaBy9Ud5bRBFVkEDu/r+rXP33wFPHjWjwvHAtfci1NRBAudQI/98DbcGQw5HmE89CjgZRo5ktkC5yu/8agEPocVjdHyZr7PaHfxZGUDGKtGRL2QzRYukCmWo1cZbMBHcI5FzImvTHS9/8B3SATjXMPgbfBuEeBwuBK5EjL+CtHY5bWs9kmYjmeo0KfUMH8hY4MAXDoKhQ7DhBPIrcjS5jPtoGxIREZjba67r6/P2XKXaCZH6Fc= charlie@somemail.org 2011-01-17"

Playbook Example 
================

---
# include like this:
# - include: tasks/logins.yaml users=charlie,sue
- name: create user charlie
  action: user name=charlie shell=/bin/bash createhome=yes groups=www-data 
  only_if: "'charlie' in '$users'"
- name: add public key for charlie
  action: authorized_key user=charlie key="ssh-dss AAAABUfOL+8BTwaRYr/rycsBF1D8e5pTxEsXHQs4iq+mZdyWqlW++L6pMiam1A8yweP+rKtgjK2httVS6GigVsuWWfOd7/sdWippefq74nppVUELHPKkaIOjJNN1zUHFoL/YMwAAAEBALnAsQN10TNGsRDe5arBsW8cTOjqLyYBcIqgPYTZW8zENErFxt7ij3fW3Jh/sCpnmy8rkS7FyK8ULX0PEy/2yDx8/5rXgMIICbRH/XaBy9Ud5bRBFVkEDu/r+rXP33wFPHjWjwvHAtfci1NRBAudQI/98DbcGQw5HmE89CjgZRo5ktkC5yu/8agEPocVjdHyZr7PaHfxZGUDGKtGRL2QzRYukCmWo1cZbMBHcI5FzImvTHS9/8B3SATjXMPgbfBuEeBwuBK5EjL+CtHY5bWs9kmYjmeo0KfUMH8hY4MAXDoKhQ7DhBPIrcjS5jPtoGxIREZjba67r6/P2XKXaCZH6Fc= charlie@somemail.org 2011-01-17"
  only_if: "'charlie' in '$users'"


This file is part of Ansible

Ansible is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Ansible is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
"""

try:
    import json
except ImportError:
    import simplejson as json

import sys, os, shlex, pwd, syslog
from os.path import expanduser, exists, isfile, join

params = {}
msg=""

def exit_json(rc=0, **kwargs):
    if 'name' in kwargs:
        add_user_info(kwargs)
    print json.dumps(kwargs)
    sys.exit(rc)

def fail_json(**kwargs):
    kwargs['failed'] = True
    exit_json(rc=1, **kwargs)

def get_params():
    """Startup tasks and read params.

    :return: parameters as dictionary.
    """
    global msg

    msg = "reading params"
    argfile = sys.argv[1]
    try:
        f = open(argfile,"r")
        args = f.read()
    finally:
        f.close()

    msg = "writing syslog."
    syslog.openlog('ansible-%s' % os.path.basename(__file__))
    syslog.syslog(syslog.LOG_NOTICE, 'Invoked with %s' % args)

    msg = "parsing params"
    params = dict(                            # make a dictionary of...
        [ arg.split("=", 1)                 # assignment pairs 
          for arg in shlex.split(args)  # using shell lexing
          if "=" in arg                     # ignoring tokens without assignment
        ])

    return params

def keyfile(user, write=False):
    """Calculate name of authorized keys file, optionally creating the 
    directories and file, properly setting permissions.

    :param str user: name of user in passwd file
    :param bool write: if True, write changes to authorized_keys file (creating directories if needed)
    :return: full path string to authorized_keys for user
    """

    global msg
    msg = "Reading system user entry."
    user_entry = pwd.getpwnam(user)
    msg = "Calculating special directories"
    homedir = user_entry.pw_dir
    sshdir = join(homedir, ".ssh")
    keysfile = join(sshdir, "authorized_keys")
    if not write: return keysfile

    #create directories and files for authorized keys
    msg = "Reading user and group info."
    uid = user_entry.pw_uid
    gid = user_entry.pw_gid
    msg = "Making ~/.ssh."
    if not exists(sshdir): os.mkdir(sshdir, 0700)
    os.chown(sshdir, uid, gid)
    os.chmod(sshdir, 0700)
    msg = "Touching authorized keys file."
    if not exists( keysfile):
        try:
            f = open(keysfile, "w") #touches file so we can set ownership and perms
        finally:
            f.close()
    os.chown(keysfile, uid, gid)
    os.chmod(keysfile, 0600)
    return keysfile

def readkeys( filename):
    global msg
    msg = "Reading authorized_keys."
    if not isfile(filename): return []
    try:
        f = open(filename)
        keys = [line.rstrip() for line in f.readlines()]
    finally:
        f.close()
    return keys

def writekeys( filename, keys):
    global msg
    msg = "Writing authorized_keys."
    try:
        f = open(filename,"w")
        f.writelines( (key + "\n" for key in keys) )
    finally:
        f.close()

def enforce_state( params):
    """Add or remove key.

    :return: True=changed, False=unchanged
    """
    global msg

    #== scrub params
    msg = "Invalid or missing param: user."
    user = params["user"]
    msg = "Invalid or missing param: key."
    key = params["key"]
    state = params.get("state", "present")

    #== check current state
    params["keyfile"] = keyfile(user, write=False) #just get the filename, don't create file
    keys = readkeys( params["keyfile"])
    present = key in keys

    #== handle idempotent state=present
    if state=="present":
        if present: return False #nothing to do
        keys.append(key)
        writekeys(keyfile(user,write=True), keys)
    elif state=="absent":
        if not present: return False #nothing to do
        keys.remove(key)
        writekeys(keyfile(user,write=True), keys)
    else:
        msg = "Invalid param: state."
        raise StandardError(msg)
    return True

#===== MAIN SCRIPT ===================================================

try:
    params = get_params()
    changed = enforce_state( params)
    msg = ""
except:
    msg = "Error %s" % msg

# Don't do sys.exit() within try...except 
if msg:
    fail_json(msg=msg)
else:
    exit_json( user=params["user"], changed=changed)