本文主要是记录如何编写ansible的连接插件（systemd-nspawn替换chroot连接），并在自己的项目中应用进去。
模仿内置的chroot连接插件方式，修改一下。通过pip3方式安装的连接插件目录：/usr/local/lib/python3.7/dist-packages/ansible/plugins/connection/在此目录下，可以看到官方的所有连接插件。
本文从ansible上游issue中，找到一份PR, 摘取下来，改动部分内容
# 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/>.
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
DOCUMENTATION = """
author: Maykel Moya <[email protected]>; xiaolong<[email protected]>
connection: nspawn
short_description: Interact with local systemd-nspawn container
description:
- Run commands or put/fetch files to an existing systemd-nspawn
container on the Ansible controller. Unlike the chroot driver,
this will ensure that /proc, /sys, and /dev are all properly
configured.
- Set "ansible_nspawn_args" to pass additional arguments to
systemd-nspawn (e.g., --bind, --private-network, --private-user,
etc).
version_added: "2.9"
options:
remote_addr:
description:
- The path of the chroot you want to access.
default: inventory_hostname
vars:
- name: ansible_host
executable:
description:
- User specified executable shell
ini:
- section: defaults
key: executable
env:
- name: ANSIBLE_EXECUTABLE
vars:
- name: ansible_executable
nspawn_args:
description:
- Extra command line arguments to pass to systemd-nspawn
env:
- name: ANSIBLE_NSPAWN_ARGS
vars:
- name: ansible_nspawn_args
default: ''
"""
import distutils.spawn
import os
import os.path
import subprocess
import traceback
import shlex
from ansible import constants as C
from ansible.module_utils import six
from ansible.module_utils.six.moves import shlex_quote
from ansible.errors import AnsibleError
from ansible.module_utils._text import to_bytes, to_text
from ansible.plugins.connection import ConnectionBase, BUFSIZE
try:
from __main__ import display
except ImportError:
from ansible.utils.display import Display
display = Display()
class Connection(ConnectionBase):
''' Local nspawn based connections '''
transport = 'nspawn'
has_pipelining = True
# become_methods = frozenset(C.BECOME_METHODS)
def __init__(self, play_context, new_stdin, *args, **kwargs):
super(Connection, self).__init__(play_context, new_stdin,
*args, **kwargs)
# display.vvv("NSPAWN ARGS %s" % self._play_context.nspawn_args)
display.vvv("NSPAWN ARGS %s" % self.get_option('nspawn_args'))
self.ostree = os.path.normpath(self._play_context.remote_addr)
if os.geteuid() != 0:
raise AnsibleError("nspawn connection requires running as root")
# we're running as root on the local system so do some
# trivial checks for ensuring 'host' may be an OS tree dir
if not os.path.isdir(self.ostree):
raise AnsibleError("%s is not a directory" % self.ostree)
# As systemd-nspawn will, we check the existence of os-release files
# in the container tree to think it looks like an OS tree enough
# see man systemd-nspawn(1) and os-release(5)
if not (
os.path.isfile(os.path.join(self.ostree, "usr/library/os-release"))
or os.path.isfile(os.path.join(self.ostree, "etc/os-release"))
):
raise AnsibleError("%s does not contain an os-release file"
% self.ostree)
self.nspawn_cmd = distutils.spawn.find_executable('systemd-nspawn')
if not self.nspawn_cmd:
raise AnsibleError("systemd-nspawn command not found in PATH")
def _connect(self):
''' Connect to the container. Nothing to do '''
super(Connection, self)._connect()
if not self._connected:
display.vvv(u"THIS IS A LOCAL NSPAWN CONTAINER", host=self.ostree)
self._connected = True
def _buffered_exec_command(self, cmd, stdin=subprocess.PIPE):
''' run a command in the container. This is only needed for
implementing put_file() get_file() so that we don't have to
read the whole file into memory.
compared to exec_command() it looses some niceties like being
able to return the process's exit code immediately.
'''
executable = (
C.DEFAULT_EXECUTABLE.split()[0]
if C.DEFAULT_EXECUTABLE
else '/bin/sh')
nspawn_args = self.get_option('nspawn_args')
if six.PY2:
nspawn_args = shlex.split(
to_bytes(nspawn_args, errors='surrogate_or_strict')
)
else:
nspawn_args = shlex.split(
to_text(nspawn_args, errors='surrogate_or_strict')
)
local_cmd = [self.nspawn_cmd, '-D', self.ostree, '-q'] + nspawn_args + [
'--', executable, '-c', cmd]
display.vvv("EXEC %s" % (local_cmd), host=self.ostree)
local_cmd = [to_bytes(i, errors='surrogate_or_strict')
for i in local_cmd]
p = subprocess.Popen(local_cmd, shell=False, stdin=stdin,
stdout=subprocess.PIPE, stderr=subprocess.PIPE)
return p
def exec_command(self, cmd, in_data=None, sudoable=False):
''' run a command in the container '''
super(Connection, self).exec_command(cmd, in_data=in_data,
sudoable=sudoable)
p = self._buffered_exec_command(cmd)
stdout, stderr = p.communicate(in_data)
return (p.returncode, stdout, stderr)
def _prefix_login_path(self, remote_path):
''' Make sure that we put files into a standard path
If a path is relative, then we need to choose where to put it.
ssh chooses $HOME but we aren't guaranteed that a home dir will
exist in any given container. So for now we're choosing "/"
instead.
This also happens to be the former default.
Can revisit using $HOME instead if it's a problem
'''
if not remote_path.startswith(os.path.sep):
remote_path = os.path.join(os.path.sep, remote_path)
return os.path.normpath(remote_path)
def put_file(self, in_path, out_path):
''' transfer a file from local to the container '''
super(Connection, self).put_file(in_path, out_path)
display.vvv("PUT %s TO %s" % (in_path, out_path), host=self.ostree)
out_path = shlex_quote(self._prefix_login_path(out_path))
try:
with open(to_bytes(in_path, errors='surrogate_or_strict'),
'rb') as in_file:
try:
p = self._buffered_exec_command(
'dd of=%s bs=%s' % (out_path, BUFSIZE),
stdin=in_file
)
except OSError:
raise AnsibleError(
"nspawn connection requires dd command in container"
)
try:
stdout, stderr = p.communicate()
except:
traceback.print_exc()
raise AnsibleError("failed to transfer file %s to %s"
% (in_path, out_path))
if p.returncode != 0:
raise AnsibleError(
"failed to transfer file %s to %s:\n%s\n%s"
% (in_path, out_path, stdout, stderr)
)
except IOError:
raise AnsibleError("file or module does not exist at: %s"
% in_path)
def fetch_file(self, in_path, out_path):
''' fetch a file from the container to local '''
super(Connection, self).fetch_file(in_path, out_path)
display.vvv("FETCH %s TO %s" % (in_path, out_path), host=self.ostree)
in_path = shlex_quote(self._prefix_login_path(in_path))
try:
p = self._buffered_exec_command('dd if=%s bs=%s'
% (in_path, BUFSIZE))
except OSError:
raise AnsibleError(
"nspawn connection requires dd command in the container"
)
with open(to_bytes(out_path, errors='surrogate_or_strict'),
'wb+') as out_file:
try:
chunk = p.stdout.read(BUFSIZE)
while chunk:
out_file.write(chunk)
chunk = p.stdout.read(BUFSIZE)
except:
traceback.print_exc()
raise AnsibleError("failed to transfer file %s to %s"
% (in_path, out_path))
stdout, stderr = p.communicate()
if p.returncode != 0:
raise AnsibleError("failed to transfer file %s to %s:\n%s\n%s"
% (in_path, out_path, stdout, stderr))
def close(self):
''' terminate the connection; nothing to do here '''
super(Connection, self).close()
self._connected = False需注意：代码中的DOCUMENTATION字段很重要，刚开始就是忽略它，导致调用处无法传入参数
- 在与
ansible.cfg同层目录中，创建connection_plugins目录，将上面的nspawn.py文件放到该目录下即可使用。 - 在
host中，指定连接方式为nspawn的具体参数
[nspawn]
/var/tmp/live ansible_connection=nspawn ansible_python_interpreter=/usr/bin/python3- 在入口处，指定
hosts为nspawn后，下面执行的task均会通过systemd-nspawn方式执行