New become plugin: podman_unshare (#455)

* New become plugin: podman_unshare

Signed-off-by: Janos Gerzson <gerzsonj@gmail.com>

plugins/become/podman_unshare.py

@@ -0,0 +1,149 @@
+# -*- coding: utf-8 -*-
+# Copyright (c) 2022 Ansible Project
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+# Written by Janos Gerzson (grzs@backendo.com)
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+
+DOCUMENTATION = """
+    name: podman_unshare
+    short_description: Run tasks using podman unshare
+    description:
+        - "This become plugins allows your remote/login user
+          to execute commands in its container user namespace.
+          Official documentation: https://docs.podman.io/en/latest/markdown/podman-unshare.1.html"
+    author:
+    - Janos Gerzson (@grzs)
+    version_added: 1.9.0
+    options:
+        become_user:
+            description: User you 'become' to execute the task
+            default: root
+            ini:
+              - section: privilege_escalation
+                key: become_user
+              - section: sudo_become_plugin
+                key: user
+            vars:
+              - name: ansible_become_user
+              - name: ansible_sudo_user
+            env:
+              - name: ANSIBLE_BECOME_USER
+              - name: ANSIBLE_SUDO_USER
+            keyword:
+              - name: become_user
+        become_exe:
+            description: Sudo executable
+            default: sudo
+            ini:
+              - section: privilege_escalation
+                key: become_exe
+              - section: sudo_become_plugin
+                key: executable
+            vars:
+              - name: ansible_become_exe
+              - name: ansible_sudo_exe
+            env:
+              - name: ANSIBLE_BECOME_EXE
+              - name: ANSIBLE_SUDO_EXE
+            keyword:
+              - name: become_exe
+        become_pass:
+            description: Password to pass to sudo
+            required: False
+            vars:
+              - name: ansible_become_password
+              - name: ansible_become_pass
+              - name: ansible_sudo_pass
+            env:
+              - name: ANSIBLE_BECOME_PASS
+              - name: ANSIBLE_SUDO_PASS
+            ini:
+              - section: sudo_become_plugin
+                key: password
+"""
+
+EXAMPLES = """
+- name: checking uid of file 'foo'
+  ansible.builtin.stat:
+    path: "{{ test_dir }}/foo"
+  register: foo
+- ansible.builtin.debug:
+    var: foo.stat.uid
+# The output shows that it's owned by the login user
+# ok: [test_host] => {
+#     "foo.stat.uid": "1003"
+# }
+
+- name: mounting the file to an unprivileged container and modifying its owner
+  containers.podman.podman_container:
+    name: chmod_foo
+    image: alpine
+    rm: yes
+    volume:
+    - "{{ test_dir }}:/opt/test:z"
+    command: chown 1000 /opt/test/foo
+
+# Now the file 'foo' is owned by the container uid 1000,
+# which is mapped to something completaly different on the host.
+# It creates a situation when the file is unaccessible to the host user (uid 1003)
+# Running stat again, debug output will be like this:
+# ok: [test_host] => {
+#     "foo.stat.uid": "328679"
+# }
+
+- name: running stat in modified user namespace
+  become_method: containers.podman.podman_unshare
+  become: yes
+  ansible.builtin.stat:
+    path: "{{ test_dir }}/foo"
+  register: foo
+# By gathering file stats with podman_ushare
+# we can see the uid set in the container:
+# ok: [test_host] => {
+#     "foo.stat.uid": "1000"
+# }
+
+- name: resetting file ownership with podman unshare
+  become_method: containers.podman.podman_unshare
+  become: yes
+  ansible.builtin.file:
+    state: file
+    path: "{{ test_dir }}/foo"
+    owner: 0  # in a modified user namespace host uid is mapped to 0
+# If we run stat and debug with 'become: no',
+# we can see that the file is ours again:
+# ok: [test_host] => {
+#     "foo.stat.uid": "1003"
+# }
+"""
+
+
+from ansible.plugins.become import BecomeBase
+
+
+class BecomeModule(BecomeBase):
+
+    name = 'containers.podman.podman_unshare'
+
+    def build_become_command(self, cmd, shell):
+        super(BecomeModule, self).build_become_command(cmd, shell)
+
+        if not cmd:
+            return cmd
+
+        becomecmd = 'podman unshare'
+
+        user = self.get_option('become_user') or ''
+        if user:
+            cmdlist = [self.get_option('become_exe') or 'sudo']
+            # -i is required, because
+            # podman unshare should be executed in a login shell to avoid chdir permission errors
+            cmdlist.append('-iu %s' % user)
+            if self.get_option('become_pass'):
+                self.prompt = '[sudo podman unshare via ansible, key=%s] password:' % self._id
+                cmdlist.append('-p "%s"' % self.prompt)
+            cmdlist.append('-- %s' % becomecmd)
+            becomecmd = ' '.join(cmdlist)
+
+        return ' '.join([becomecmd, self._build_success_command(cmd, shell)])