lxc_container: replace subprocess.Popen() with run_command() (#11204)

* lxc_container: replace subprocess.Popen() with run_command()

* Update plugins/modules/lxc_container.py

Co-authored-by: Felix Fontein <felix@fontein.de>

* add changelog frag

* retain Popen logic in module_utils

* Update plugins/module_utils/_lxc.py

Co-authored-by: Felix Fontein <felix@fontein.de>

---------

Co-authored-by: Felix Fontein <felix@fontein.de>

plugins/module_utils/_lxc.py

@@ -0,0 +1,61 @@
+# Copyright (c) 2014, Kevin Carter <kevin.carter@rackspace.com>
+# Copyright (c) 2025, Alexei Znamensky <russoz@gmail.com>
+# 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
+
+import os
+import subprocess
+import tempfile
+
+from ansible.module_utils.basic import AnsibleModule
+from ansible.module_utils.common.text.converters import to_bytes
+
+
+# This is used to attach to a running container and execute commands from
+# within the container on the host.  This will provide local access to a
+# container without using SSH.  The template will attempt to work within the
+# home directory of the user that was attached to the container and source
+# that users environment variables by default.
+ATTACH_TEMPLATE = """#!/usr/bin/env bash
+pushd "$(getent passwd $(whoami)|cut -f6 -d':')"
+    if [[ -f ".bashrc" ]];then
+        source .bashrc
+        unset HOSTNAME
+    fi
+popd
+
+# User defined command
+{}
+"""
+
+
+def create_script(command: str, module: AnsibleModule) -> None:
+    """Write out a script onto a target.
+
+    This method should be backward compatible with Python when executing
+    from within the container.
+
+    :param command: command to run, this can be a script and can use spacing
+                    with newlines as separation.
+    :param module: AnsibleModule to run commands with.
+    """
+
+    script_file = ""
+    try:
+        f = tempfile.NamedTemporaryFile(prefix="lxc-attach-script", delete=False, mode="wb")
+        f.write(to_bytes(ATTACH_TEMPLATE.format(command), errors="surrogate_or_strict"))
+        script_file = f.name
+        f.flush()
+        f.close()
+
+        os.chmod(script_file, 0o0700)
+
+        with tempfile.NamedTemporaryFile(prefix="lxc-attach-script-log", delete=False, mode="ab") as stdout_file:
+            with tempfile.NamedTemporaryFile(prefix="lxc-attach-script-err", delete=False, mode="ab") as stderr_file:
+                subprocess.Popen([script_file], stdout=stdout_file, stderr=stderr_file).communicate()
+
+    finally:
+        if script_file:
+            os.remove(script_file)