community.general/plugins/connection/lxc.py

# (c) 2015, Joerg Thalheim <joerg@higgsboson.tk>
# Copyright (c) 2017 Ansible Project
# GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
# SPDX-License-Identifier: GPL-3.0-or-later

from __future__ import annotations

DOCUMENTATION = r"""
author: Joerg Thalheim (!UNKNOWN) <joerg@higgsboson.tk>
name: lxc
short_description: Run tasks in LXC containers using lxc python library
description:
  - Run commands or put/fetch files to an existing LXC container using lxc python library.
options:
  remote_addr:
    description:
      - Container identifier.
    type: string
    default: inventory_hostname
    vars:
      - name: inventory_hostname
      - name: ansible_host
      - name: ansible_lxc_host
  executable:
    default: /bin/sh
    description:
      - Shell executable.
    type: string
    vars:
      - name: ansible_executable
      - name: ansible_lxc_executable
"""

import os
import shutil
import traceback
import select
import fcntl
import errno

HAS_LIBLXC = False
try:
    import lxc as _lxc

    HAS_LIBLXC = True
except ImportError:
    pass

from ansible import errors
from ansible.module_utils.common.text.converters import to_bytes, to_native
from ansible.plugins.connection import ConnectionBase


class Connection(ConnectionBase):
    """Local lxc based connections"""

    transport = "community.general.lxc"
    has_pipelining = True
    default_user = "root"

    def __init__(self, play_context, new_stdin, *args, **kwargs):
        super().__init__(play_context, new_stdin, *args, **kwargs)

        self.container_name = None
        self.container = None

    def _connect(self):
        """connect to the lxc; nothing to do here"""
        super()._connect()

        if not HAS_LIBLXC:
            msg = "lxc python bindings are not installed"
            raise errors.AnsibleError(msg)

        container_name = self.get_option("remote_addr")
        if self.container and self.container_name == container_name:
            return

        self.container_name = container_name

        self._display.vvv("THIS IS A LOCAL LXC DIR", host=self.container_name)
        self.container = _lxc.Container(self.container_name)
        if self.container.state == "STOPPED":
            raise errors.AnsibleError(f"{self.container_name} is not running")

    @staticmethod
    def _communicate(pid, in_data, stdin, stdout, stderr):
        buf = {stdout: [], stderr: []}
        read_fds = [stdout, stderr]
        if in_data:
            write_fds = [stdin]
        else:
            write_fds = []
        while len(read_fds) > 0 or len(write_fds) > 0:
            try:
                ready_reads, ready_writes, dummy = select.select(read_fds, write_fds, [])
            except OSError as e:
                if e.args[0] == errno.EINTR:
                    continue
                raise
            for fd in ready_writes:
                in_data = in_data[os.write(fd, in_data) :]
                if len(in_data) == 0:
                    write_fds.remove(fd)
            for fd in ready_reads:
                data = os.read(fd, 32768)
                if not data:
                    read_fds.remove(fd)
                buf[fd].append(data)

        (pid, returncode) = os.waitpid(pid, 0)

        return returncode, b"".join(buf[stdout]), b"".join(buf[stderr])

    def _set_nonblocking(self, fd):
        flags = fcntl.fcntl(fd, fcntl.F_GETFL) | os.O_NONBLOCK
        fcntl.fcntl(fd, fcntl.F_SETFL, flags)
        return fd

    def exec_command(self, cmd, in_data=None, sudoable=False):
        """run a command on the chroot"""
        super().exec_command(cmd, in_data=in_data, sudoable=sudoable)

        # python2-lxc needs bytes. python3-lxc needs text.
        executable = to_native(self.get_option("executable"), errors="surrogate_or_strict")
        local_cmd = [executable, "-c", to_native(cmd, errors="surrogate_or_strict")]

        read_stdout, write_stdout = None, None
        read_stderr, write_stderr = None, None
        read_stdin, write_stdin = None, None

        try:
            read_stdout, write_stdout = os.pipe()
            read_stderr, write_stderr = os.pipe()

            kwargs = {
                "stdout": self._set_nonblocking(write_stdout),
                "stderr": self._set_nonblocking(write_stderr),
                "env_policy": _lxc.LXC_ATTACH_CLEAR_ENV,
            }

            if in_data:
                read_stdin, write_stdin = os.pipe()
                kwargs["stdin"] = self._set_nonblocking(read_stdin)

            self._display.vvv(f"EXEC {local_cmd}", host=self.container_name)
            pid = self.container.attach(_lxc.attach_run_command, local_cmd, **kwargs)
            if pid == -1:
                msg = f"failed to attach to container {self.container_name}"
                raise errors.AnsibleError(msg)

            write_stdout = os.close(write_stdout)
            write_stderr = os.close(write_stderr)
            if read_stdin:
                read_stdin = os.close(read_stdin)

            return self._communicate(pid, in_data, write_stdin, read_stdout, read_stderr)
        finally:
            fds = [read_stdout, write_stdout, read_stderr, write_stderr, read_stdin, write_stdin]
            for fd in fds:
                if fd:
                    os.close(fd)

    def put_file(self, in_path, out_path):
        """transfer a file from local to lxc"""
        super().put_file(in_path, out_path)
        self._display.vvv(f"PUT {in_path} TO {out_path}", host=self.container_name)
        in_path = to_bytes(in_path, errors="surrogate_or_strict")
        out_path = to_bytes(out_path, errors="surrogate_or_strict")

        if not os.path.exists(in_path):
            msg = f"file or module does not exist: {in_path}"
            raise errors.AnsibleFileNotFound(msg)
        try:
            src_file = open(in_path, "rb")
        except OSError as e:
            traceback.print_exc()
            raise errors.AnsibleError(f"failed to open input file to {in_path}") from e
        try:

            def write_file(args):
                with open(out_path, "wb+") as dst_file:
                    shutil.copyfileobj(src_file, dst_file)

            try:
                self.container.attach_wait(write_file, None)
            except OSError as e:
                traceback.print_exc()
                msg = f"failed to transfer file to {out_path}"
                raise errors.AnsibleError(msg) from e
        finally:
            src_file.close()

    def fetch_file(self, in_path, out_path):
        """fetch a file from lxc to local"""
        super().fetch_file(in_path, out_path)
        self._display.vvv(f"FETCH {in_path} TO {out_path}", host=self.container_name)
        in_path = to_bytes(in_path, errors="surrogate_or_strict")
        out_path = to_bytes(out_path, errors="surrogate_or_strict")

        try:
            dst_file = open(out_path, "wb")
        except OSError as e:
            traceback.print_exc()
            msg = f"failed to open output file {out_path}"
            raise errors.AnsibleError(msg) from e
        try:

            def write_file(args):
                try:
                    with open(in_path, "rb") as src_file:
                        shutil.copyfileobj(src_file, dst_file)
                finally:
                    # this is needed in the lxc child process
                    # to flush internal python buffers
                    dst_file.close()

            try:
                self.container.attach_wait(write_file, None)
            except OSError as e:
                traceback.print_exc()
                msg = f"failed to transfer file from {in_path} to {out_path}"
                raise errors.AnsibleError(msg) from e
        finally:
            dst_file.close()

    def close(self):
        """terminate the connection; nothing to do here"""
        super().close()
        self._connected = False