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#!/usr/bin/python
# -*- coding: utf-8 -*-
import re
import os
import string
DOCUMENTATION = """
---
module: sshknownhosts
short_description: Maintain the ssh_known_hosts file by adding/
removing/ updating public keys.
description:
- This module will scan a host for its ssh key and add it to the ssh
known hosts file. Typically this file is located at
/etc/ssh/ssh_known_hosts or ~user/.ssh/known_hosts.
- If the public key is already present in the known hosts file and
it does not match the current value, it is updated. Otherwise
the hosts file is untouched.
- This is an alternative to copying a file to each host using the
copy command.
options:
host:
required: true
aliases: [name]
description:
- the hostname to scan. Use a fully-qualified domain name if
possible. If used with state=absent, this specifies the
hostname (not the alias) of the key to remove from the dest file.
dest:
required: false
default: /etc/ssh/ssh_known_hosts
description:
- Full path of the file to modify. This will be created if it
does not exist.
state:
required: false
choices: [present, absent]
default: "present"
description:
- Whether the host should be there or not.
enctype:
required: false
choices: [ecdsa, rsa, dsa]
default: "rsa"
description:
- The type of public key to scan for.
port:
required: false
default: "22"
description:
- sshd server port, if it runs on a non-standard port.
keyscan:
required: false
default: "ssh-keyscan"
description:
- The full path to the program to run to do the scan. If not
specified, the module will run the ssh-keyscan program from
the path.
aliases:
required: false
default: ""
description:
- One or more aliases for this host in a comma-separated list. These
are other names a host is known by.
"""
EXAMPLES = r"""
Examples:
- name: Add localhost to ssh_known_hosts file
action: sshknownhosts host=localhost state=present
- name: Add several hosts to ssh_known_hosts file
action: sshknownhosts host={{ item }} state=present port=2222
with_items:
- host1.example.com
- host2.example.com
- host3.example.com
- name: a long example
action: sshknownhosts host=abc.example.com dest=/usr/local/etc/ssh_known_hosts keyscan=/usr/local/bin/ssh-keyscan enctype=dsa port=2222
- name: for one user id
action: sshknownhosts host=mypc dest=~myself/.ssh/knownhosts
- name: aliases example
action: sshknownhosts host=myserver aliases=mygitserver state=present
"""
# read a text file.
# return the lines as an array. if the file is not found, return an
# empty array
def read_known_hosts(dest):
if os.path.exists(dest):
f = open(dest, 'rb')
lines = f.readlines()
f.close()
else:
lines = []
return lines
# locate a host in the known hosts array.
# return the position if found, or -1 if not found
def find_host(lines, host):
# look for the hostname at the beginning of a line, followed by a
# space character or a comma
mre = re.compile(r"^" + host + '[ ,]')
found = -1
for lineno, cur_line in enumerate(lines):
if mre.search(cur_line):
found = lineno
return found
# write the new/changed file. this is the only place where system
# changes are performed
def write_known_hosts(module, dest, lines):
if not module.check_mode:
of = open(dest, 'wb')
of.writelines(lines)
of.close
# scan the remote host.
# return an array: [rc, str]
# rc = return code: 0 = success, -1 = error
# str = public key or error message
def scan_key(module, host, keyscan, enctype, port):
cmd = keyscan + ' -p ' + port + ' -t ' + enctype + ' ' + host
(rc, out, err) = module.run_command(cmd)
# look for a non-blank string
mre = re.compile(r"^\s*$")
if not mre.search(out):
return [0, out]
else:
return [-1, err.strip()]
# add aliases into knownhosts line.
# key = the line returned by keyscan
# aliases = the list of comma-separated aliases, or ''
def add_aliases(key, aliases):
if aliases == '':
return key
parts = string.split(key, ' ', 1) # split at first space (into 2 parts)
return parts[0] + ',' + aliases + ' ' + parts[1]
def present(module, dest, host, keyscan, enctype, port, aliases):
changed = False
msg = ""
lines = read_known_hosts(dest)
found = find_host(lines, host)
rc, key = scan_key(module, host, keyscan, enctype, port)
if rc == 0:
key = add_aliases(key, aliases)
if found != -1:
if key != lines[found]:
# replace
del lines[found]
lines.append(key)
write_known_hosts(module, dest, lines)
changed = True
else:
# add
lines.append(key)
write_known_hosts(module, dest, lines)
changed = True
else:
# error: return the error message to the user
msg = key
module.exit_json(changed=changed, msg=msg)
def absent(module, dest, host):
changed = False
msg = ""
lines = read_known_hosts(dest)
found = find_host(lines, host)
if found != -1:
del lines[found]
write_known_hosts(module, dest, lines)
changed = True
module.exit_json(changed=changed, msg=msg)
def main():
module = AnsibleModule(
argument_spec=dict(
host=dict(required=True, aliases=['name']),
dest=dict(default='/etc/ssh/ssh_known_hosts'),
enctype=dict(default='rsa', choices=['ecdsa', 'rsa', 'dsa']),
keyscan=dict(default='ssh-keyscan'),
port=dict(default='22'),
state=dict(default='present', choices=['absent', 'present']),
aliases=dict(default=''),
),
supports_check_mode=True
)
host = module.params['host']
keyscan = module.params['keyscan']
port = module.params['port']
enctype = module.params['enctype']
dest = os.path.expanduser(module.params['dest'])
aliases = module.params['aliases']
if 'host' not in module.params:
module.fail_json(msg='host= is required')
if module.params['state'] == 'present':
present(module, dest, host, keyscan, enctype, port, aliases)
else:
absent(module, dest, host)
# this is magic, see lib/ansible/module_common.py
#<<INCLUDE_ANSIBLE_MODULE_COMMON>>
main()
|
