ansible/library/commands/command

#!/usr/bin/python
# -*- coding: utf-8 -*-

# (c) 2012, Michael DeHaan <michael.dehaan@gmail.com>, and others
#
# 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/>.

import sys
import datetime
import traceback
import re
import shlex
import os

DOCUMENTATION = '''
---
module: command
version_added: historical
short_description: Executes a command on a remote node
description:
     - The M(command) module takes the command name followed by a list of space-delimited arguments.
     - The given command will be executed on all selected nodes. It will not be
       processed through the shell, so variables like C($HOME) and operations
       like C("<"), C(">"), C("|"), and C("&") will not work (use the M(shell)
       module if you need these features).
options:
  free_form:
    description:
      - the command module takes a free form command to run.  There is no parameter actually named 'free form'.
        See the examples!
    required: true
    default: null
    aliases: []
  creates:
    description:
      - a filename, when it already exists, this step will B(not) be run.
    required: no
    default: null
  removes:
    description:
      - a filename, when it does not exist, this step will B(not) be run.
    version_added: "0.8"
    required: no
    default: null
  chdir:
    description:
      - cd into this directory before running the command
    version_added: "0.6"
    required: false
    default: null
  executable:
    description:
      - change the shell used to execute the command. Should be an absolute path to the executable.
    required: false
    default: null
    version_added: "0.9"
notes:
    -  If you want to run a command through the shell (say you are using C(<),
       C(>), C(|), etc), you actually want the M(shell) module instead. The
       M(command) module is much more secure as it's not affected by the user's
       environment.
    -  " C(creates), C(removes), and C(chdir) can be specified after the command. For instance, if you only want to run a command if a certain file does not exist, use this."
author: Michael DeHaan
'''

EXAMPLES = '''
# Example from Ansible Playbooks.
- command: /sbin/shutdown -t now

# Run the command if the specified file does not exist.
- command: /usr/bin/make_database.sh arg1 arg2 creates=/path/to/database

# You can also use the 'args' form to provide the options. This command
# will change the working directory to somedir/ and will only run when
# /path/to/database doesn't exist.
- command: /usr/bin/make_database.sh arg1 arg2
  args:
    chdir: somedir/
    creates: /path/to/database
'''

# This is a pretty complex regex, which functions as follows:
#
# 1. (^|\s)
# ^ look for a space or the beginning of the line
# 2. (creates|removes|chdir|executable|NO_LOG)=
# ^ look for a valid param, followed by an '='
# 3. (?P<quote>[\'"])?
# ^ look for an optional quote character, which can either be
#   a single or double quote character, and store it for later
# 4. (.*?)
# ^ match everything in a non-greedy manner until...
# 5. (?(quote)(?<!\\)(?P=quote))((?<!\\)(?=\s)|$)
# ^ a non-escaped space or a non-escaped quote of the same kind
#   that was matched in the first 'quote' is found, or the end of
#   the line is reached

PARAM_REGEX = re.compile(r'(^|\s)(creates|removes|chdir|executable|NO_LOG)=(?P<quote>[\'"])?(.*?)(?(quote)(?<!\\)(?P=quote))((?<!\\)(?=\s)|$)')

def main():

    # the command module is the one ansible module that does not take key=value args
    # hence don't copy this one if you are looking to build others!
    module = CommandModule(argument_spec=dict())

    shell = module.params['shell']
    chdir = module.params['chdir']
    executable = module.params['executable']
    args  = module.params['args']
    creates  = module.params['creates']
    removes  = module.params['removes']

    if args.strip() == '':
        module.fail_json(rc=256, msg="no command given")

    if chdir:
        os.chdir(chdir)

    if creates:
        # do not run the command if the line contains creates=filename
        # and the filename already exists.  This allows idempotence
        # of command executions.
        v = os.path.expanduser(creates)
        if os.path.exists(v):
            module.exit_json(
                cmd=args,
                stdout="skipped, since %s exists" % v,
                skipped=True,
                changed=False,
                stderr=False,
                rc=0
            )

    if removes:
    # do not run the command if the line contains removes=filename
    # and the filename does not exist.  This allows idempotence
    # of command executions.
        v = os.path.expanduser(removes)
        if not os.path.exists(v):
            module.exit_json(
                cmd=args,
                stdout="skipped, since %s does not exist" % v,
                skipped=True,
                changed=False,
                stderr=False,
                rc=0
            )

    if not shell:
        args = shlex.split(args)
    startd = datetime.datetime.now()

    rc, out, err = module.run_command(args, executable=executable, use_unsafe_shell=shell)

    endd = datetime.datetime.now()
    delta = endd - startd

    if out is None:
        out = ''
    if err is None:
        err = ''

    module.exit_json(
        cmd     = args,
        stdout  = out.rstrip("\r\n"),
        stderr  = err.rstrip("\r\n"),
        rc      = rc,
        start   = str(startd),
        end     = str(endd),
        delta   = str(delta),
        changed = True
    )

# import module snippets
from ansible.module_utils.basic import *

# only the command module should ever need to do this
# everything else should be simple key=value

class CommandModule(AnsibleModule):

    def _handle_aliases(self):
        return {}

    def _check_invalid_arguments(self):
        pass

    def _load_params(self):
        ''' read the input and return a dictionary and the arguments string '''
        args = MODULE_ARGS
        params = {}
        params['chdir']      = None
        params['creates']    = None
        params['removes']    = None
        params['shell']      = False
        params['executable'] = None
        if "#USE_SHELL" in args:
            args = args.replace("#USE_SHELL", "")
            params['shell'] = True

        # use shlex to split up the args, while being careful to preserve
        # single quotes so they're not removed accidentally
        lexer = shlex.shlex(args)
        lexer.whitespace = '\t '
        lexer.whitespace_split = True
        items = list(lexer)

        for x in items:
            quoted = x.startswith('"') and x.endswith('"') or x.startswith("'") and x.endswith("'")
            if '=' in x and not quoted:
                # check to see if this is a special parameter for the command
                k, v = x.split('=', 1)
                # because we're not breaking out quotes in the shlex split
                # above, the value of the k=v pair may still be quoted. If
                # so, remove them.
                if len(v) > 1 and (v.startswith('"') and v.endswith('"') or v.startswith("'") and v.endswith("'")):
                    v = v[1:-1]
                if k in ('creates', 'removes', 'chdir', 'executable', 'NO_LOG'):
                    if k == "chdir":
                        v = os.path.abspath(os.path.expanduser(v))
                        if not (os.path.exists(v) and os.path.isdir(v)):
                            self.fail_json(rc=258, msg="cannot change to directory '%s': path does not exist" % v)
                    elif k == "executable":
                        v = os.path.abspath(os.path.expanduser(v))
                        if not (os.path.exists(v)):
                            self.fail_json(rc=258, msg="cannot use executable '%s': file does not exist" % v)
                    params[k] = v
        # Remove any of the above k=v params from the args string
        args = PARAM_REGEX.sub('', args)
        params['args'] = args.strip()
        return (params, params['args'])

main()