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add systemd-nspawn connection driver

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This commit adds a connection driver built on top of systemd-nspawn.
This is similar to the existing `chroot` driver, except that nspawn
offers a variety of additional services. For example, it takes care of
automatically mounting `/proc` and `/sys` inside the chroot environment,
which will make a variety of tools work correctly that would otherwise
fail.

You can take advantage of other system-nspawn features to perform more
complicated tasks.  For example, on my x86_64 system I have a Raspberry
Pi disk image mounted on `/rpi`.  I can't use `chroot` with this because
the binaries contained in the image are for the wrong architecture.
However, I can use the systemd-nspawn `--bind` option to automatically
insert the appropriate qemu-arm binary into the container using an
inventory file like this:

    pi ansible_host=/rpi ansible_nspawn_extra_args='--bind /usr/bin/qemu-arm --bind /lib64'

See http://www.freedesktop.org/software/systemd/man/systemd-nspawn.html
for more information about systemd-nspawn itself.
This commit is contained in:
Lars Kellogg-Stedman 2016-02-05 11:01:38 -05:00 committed by Brian Coca
parent 482f882798
commit 3597ca082b
3 changed files with 157 additions and 0 deletions
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2
lib/ansible/cli/__init__.py
View file

@ -355,6 +355,8 @@ class CLI(with_metaclass(ABCMeta, object)):
help="specify extra arguments to pass to scp only (e.g. -l)")
connect_group.add_option('--ssh-extra-args', default='', dest='ssh_extra_args',
help="specify extra arguments to pass to ssh only (e.g. -R)")
connect_group.add_option('--nspawn-extra-args', default='', dest='nspawn_extra_args',
help="specify extra arguments to pass to systemd-nspawn only (e.g. --bind)")
parser.add_option_group(connect_group)

1
lib/ansible/constants.py
View file

@ -346,6 +346,7 @@ PARAMIKO_LOOK_FOR_KEYS = get_config(p, 'paramiko_connection', 'look_for_
PERSISTENT_CONNECT_TIMEOUT = get_config(p, 'persistent_connection', 'connect_timeout', 'ANSIBLE_PERSISTENT_CONNECT_TIMEOUT', 30, value_type='integer')
PERSISTENT_CONNECT_RETRIES = get_config(p, 'persistent_connection', 'connect_retries', 'ANSIBLE_PERSISTENT_CONNECT_RETRIES', 10, value_type='integer')
PERSISTENT_CONNECT_INTERVAL = get_config(p, 'persistent_connection', 'connect_interval', 'ANSIBLE_PERSISTENT_CONNECT_INTERVAL', 1, value_type='integer')
ANSIBLE_NSPAWN_ARGS = get_config(p, 'nspawn_connection', 'nspawn_args', 'ANSIBLE_NSPAWN_ARGS', '-q')
# obsolete -- will be formally removed
ACCELERATE_PORT = get_config(p, 'accelerate', 'accelerate_port', 'ACCELERATE_PORT', 5099, value_type='integer')

154
lib/ansible/plugins/connection/nspawn.py Normal file
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@ -0,0 +1,154 @@
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
import os
import pipes
import subprocess
import traceback
import shlex
from ansible import constants as C
from ansible.errors import AnsibleError
from ansible.plugins.connection import ConnectionBase
from ansible.module_utils.basic import is_executable
from ansible.utils.unicode import to_bytes
try:
from __main__ import display
except ImportError:
from ansible.utils.display import Display
display = Display()
BUFSIZE = 65536
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 EXTRA ARGS %s" % self._play_context.nspawn_extra_args)
self.chroot = 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' is actually a chroot'able dir
if not os.path.isdir(self.chroot):
raise AnsibleError("%s is not a directory" % self.chroot)
chrootsh = os.path.join(self.chroot, 'bin/sh')
if not is_executable(chrootsh):
raise AnsibleError("%s does not look like a chrootable dir (/bin/sh missing)" % self.chroot)
self.nspawn_cmd = 'systemd-nspawn'
def _connect(self):
pass
def _buffered_exec_command(self, cmd, stdin=subprocess.PIPE):
''' run a command on the chroot. 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 = shlex.split(self._play_context.nspawn_args)
nspawn_extra_args = shlex.split(self._play_context.nspawn_extra_args)
local_cmd = [self.nspawn_cmd, '-D', self.chroot ] + nspawn_args + nspawn_extra_args + [
'--', executable, '-c', cmd]
display.vvv("EXEC %s" % (local_cmd), host=self.chroot)
local_cmd = map(to_bytes, 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 on the chroot '''
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 chroot. 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 chroot '''
super(Connection, self).put_file(in_path, out_path)
display.vvv("PUT %s TO %s" % (in_path, out_path), host=self.chroot)
out_path = pipes.quote(self._prefix_login_path(out_path))
try:
with open(in_path, '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("chroot connection requires dd command in the chroot")
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 chroot to local '''
super(Connection, self).fetch_file(in_path, out_path)
display.vvv("FETCH %s TO %s" % (in_path, out_path), host=self.chroot)
in_path = pipes.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("chroot connection requires dd command in the chroot")
with open(out_path, '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