Become plugins (#50991)

* [WIP] become plugins

Move from hardcoded method to plugins for ease of use, expansion and overrides
  - load into connection as it is going to be the main consumer
  - play_context will also use to keep backwards compat API
  - ensure shell is used to construct commands when needed
  - migrate settings remove from base config in favor of plugin specific configs
  - cleanup ansible-doc
  - add become plugin docs
  - remove deprecated sudo/su code and keywords
  - adjust become options for cli
  - set plugin options from context
  - ensure config defs are avaialbe before instance
  - refactored getting the shell plugin, fixed tests
     - changed into regex as they were string matching, which does not work with random string generation
     - explicitly set flags for play context tests
 - moved plugin loading up front
 - now loads for basedir also
 - allow pyc/o for non m modules
 - fixes to tests and some plugins
 - migrate to play objects fro play_context
 - simiplify gathering
 -  added utf8 headers
 - moved option setting
 - add fail msg to dzdo
 - use tuple for multiple options on fail/missing
 - fix relative plugin paths
 - shift from play context to play
 - all tasks already inherit this from play directly
 - remove obsolete 'set play'
 - correct environment handling
 - add wrap_exe option to pfexec
 - fix runas to noop
 - fixed setting play context
 - added password configs
 - removed required false
 - remove from doc building till they are ready

future development:
  - deal with 'enable' and 'runas' which are not 'command wrappers' but 'state flags' and currently hardcoded in diff subsystems

* cleanup

  remove callers to removed func
  removed --sudo cli doc refs
  remove runas become_exe
  ensure keyerorr on plugin
  also fix backwards compat, missing method is attributeerror, not ansible error
  get remote_user consistently
  ignore missing system_tmpdirs on plugin load
  correct config precedence
  add deprecation
  fix networking imports
  backwards compat for plugins using BECOME_METHODS

* Port become_plugins to context.CLIARGS

This is a work in progress:
* Stop passing options around everywhere as we can use context.CLIARGS
  instead

* Refactor make_become_commands as asked for by alikins

* Typo in comment fix

* Stop loading values from the cli in more than one place

Both play and play_context were saving default values from the cli
arguments directly.  This changes things so that the default values are
loaded into the play and then play_context takes them from there.

* Rename BECOME_PLUGIN_PATH to DEFAULT_BECOME_PLUGIN_PATH

As alikins said, all other plugin paths are named
DEFAULT_plugintype_PLUGIN_PATH.  If we're going to rename these, that
should be done all at one time rather than piecemeal.

* One to throw away

This is a set of hacks to get setting FieldAttribute defaults to command
line args to work.  It's not fully done yet.

After talking it over with sivel and jimi-c this should be done by
fixing FieldAttributeBase and _get_parent_attribute() calls to do the
right thing when there is a non-None default.

What we want to be able to do ideally is something like this:

class Base(FieldAttributeBase):
    _check_mode = FieldAttribute([..] default=lambda: context.CLIARGS['check'])

class Play(Base):
    # lambda so that we have a chance to parse the command line args
    # before we get here.  In the future we might be able to restructure
    # this so that the cli parsing code runs before these classes are
    # defined.

class Task(Base):
    pass

And still have a playbook like this function:

---
- hosts:
  tasks:
  - command: whoami
    check_mode: True

(The check_mode test that is added as a separate commit in this PR will
let you test variations on this case).

There's a few separate reasons that the code doesn't let us do this or
a non-ugly workaround for this as written right now.  The fix that
jimi-c, sivel, and I talked about may let us do this or it may still
require a workaround (but less ugly) (having one class that has the
FieldAttributes with default values and one class that inherits from
that but just overrides the FieldAttributes which now have defaults)

* Revert "One to throw away"

This reverts commit 23aa883cbed11429ef1be2a2d0ed18f83a3b8064.

* Set FieldAttr defaults directly from CLIARGS

* Remove dead code

* Move timeout directly to PlayContext, it's never needed on Play

* just for backwards compat, add a static version of BECOME_METHODS to constants

* Make the become attr on the connection public, since it's used outside of the connection

* Logic fix

* Nuke connection testing if it supports specific become methods

* Remove unused vars

* Address rebase issues

* Fix path encoding issue

* Remove unused import

* Various cleanups

* Restore network_cli check in _low_level_execute_command

* type improvements for cliargs_deferred_get and swap shallowcopy to default to False

* minor cleanups

* Allow the su plugin to work, since it doesn't define a prompt the same way

* Fix up ksu become plugin

* Only set prompt if build_become_command was called

* Add helper to assist connection plugins in knowing they need to wait for a prompt

* Fix tests and code expectations

* Doc updates

* Various additional minor cleanups

* Make doas functional

* Don't change connection signature, load become plugin from TaskExecutor

* Remove unused imports

* Add comment about setting the become plugin on the playcontext

* Fix up tests for recent changes

* Support 'Password:' natively for the doas plugin

* Make default prompts raw

* wording cleanups. ci_complete

* Remove unrelated changes

* Address spelling mistake

* Restore removed test, and udpate to use new functionality

* Add changelog fragment

* Don't hard fail in set_attributes_from_cli on missing CLI keys

* Remove unrelated change to loader

* Remove internal deprecated FieldAttributes now

* Emit deprecation warnings now

lib/ansible/executor/task_executor.py

@@ -23,6 +23,7 @@ from ansible.module_utils._text import to_text, to_native
 from ansible.module_utils.connection import write_to_file_descriptor
 from ansible.playbook.conditional import Conditional
 from ansible.playbook.task import Task
+from ansible.plugins.loader import become_loader
 from ansible.template import Templar
 from ansible.utils.listify import listify_lookup_plugin_terms
 from ansible.utils.unsafe_proxy import UnsafeProxy, wrap_var
@@ -590,7 +591,6 @@ class TaskExecutor:
             self._connection._play_context = self._play_context
 
         self._set_connection_options(variables, templar)
-        self._set_shell_options(variables, templar)
 
         # get handler
         self._handler = self._get_action_handler(connection=self._connection, templar=templar)
@@ -849,6 +849,13 @@ class TaskExecutor:
         else:
             return async_result
 
+    def _get_become(self, name):
+        become = become_loader.get(name)
+        if not become:
+            raise AnsibleError("Invalid become method specified, could not find matching plugin: '%s'. "
+                               "Use `ansible-doc -t become -l` to list available plugins." % name)
+        return become
+
     def _get_connection(self, variables, templar):
         '''
         Reads the connection property for the host, and returns the
@@ -869,8 +876,8 @@ class TaskExecutor:
                     if isinstance(i, string_types) and i.startswith("ansible_") and i.endswith("_interpreter"):
                         variables[i] = delegated_vars[i]
 
+        # load connection
         conn_type = self._play_context.connection
-
         connection = self._shared_loader_obj.connection_loader.get(
             conn_type,
             self._play_context,
@@ -882,8 +889,30 @@ class TaskExecutor:
         if not connection:
             raise AnsibleError("the connection plugin '%s' was not found" % conn_type)
 
+        # load become plugin if needed
+        become_plugin = None
+        if self._play_context.become:
+            become_plugin = self._get_become(self._play_context.become_method)
+
+        if getattr(become_plugin, 'require_tty', False) and not getattr(connection, 'has_tty', False):
+            raise AnsibleError(
+                "The '%s' connection does not provide a tty which is requied for the selected "
+                "become plugin: %s." % (conn_type, become_plugin.name)
+            )
+
+        try:
+            connection.set_become_plugin(become_plugin)
+        except AttributeError:
+            # Connection plugin does not support set_become_plugin
+            pass
+
+        # Backwards compat for connection plugins that don't support become plugins
+        # Just do this unconditionally for now, we could move it inside of the
+        # AttributeError above later
+        self._play_context.set_become_plugin(become_plugin)
+
         # FIXME: remove once all plugins pull all data from self._options
-        self._play_context.set_options_from_plugin(connection)
+        self._play_context.set_attributes_from_plugin(connection)
 
         if any(((connection.supports_persistence and C.USE_PERSISTENT_CONNECTIONS), connection.force_persistence)):
             self._play_context.timeout = connection.get_option('persistent_command_timeout')
@@ -912,13 +941,30 @@ class TaskExecutor:
 
         return options
 
+    def _set_plugin_options(self, plugin_type, variables, templar, task_keys):
+        try:
+            plugin = getattr(self._connection, '_%s' % plugin_type)
+        except AttributeError:
+            # Some plugins are assigned to private attrs, ``become`` is not
+            plugin = getattr(self._connection, plugin_type)
+        option_vars = C.config.get_plugin_vars(plugin_type, plugin._load_name)
+        options = {}
+        for k in option_vars:
+            if k in variables:
+                options[k] = templar.template(variables[k])
+        # TODO move to task method?
+        plugin.set_options(task_keys=task_keys, var_options=options)
+
     def _set_connection_options(self, variables, templar):
 
         # Keep the pre-delegate values for these keys
         PRESERVE_ORIG = ('inventory_hostname',)
 
         # create copy with delegation built in
-        final_vars = combine_vars(variables, variables.get('ansible_delegated_vars', dict()).get(self._task.delegate_to, dict()))
+        final_vars = combine_vars(
+            variables,
+            variables.get('ansible_delegated_vars', {}).get(self._task.delegate_to, {})
+        )
 
         # grab list of usable vars for this plugin
         option_vars = C.config.get_plugin_vars('connection', self._connection._load_name)
@@ -937,17 +983,25 @@ class TaskExecutor:
                 if k.startswith('ansible_%s_' % self._connection._load_name) and k not in options:
                     options['_extras'][k] = templar.template(final_vars[k])
 
-        # set options with 'templated vars' specific to this plugin
-        self._connection.set_options(var_options=options)
-        self._set_shell_options(final_vars, templar)
+        task_keys = self._task.dump_attrs()
 
-    def _set_shell_options(self, variables, templar):
-        option_vars = C.config.get_plugin_vars('shell', self._connection._shell._load_name)
-        options = {}
-        for k in option_vars:
-            if k in variables:
-                options[k] = templar.template(variables[k])
-        self._connection._shell.set_options(var_options=options)
+        # set options with 'templated vars' specific to this plugin and dependant ones
+        self._connection.set_options(task_keys=task_keys, var_options=options)
+        self._set_plugin_options('shell', final_vars, templar, task_keys)
+
+        if self._connection.become is not None:
+            # FIXME: find alternate route to provide passwords,
+            # keep out of play objects to avoid accidental disclosure
+            task_keys['become_pass'] = self._play_context.become_pass
+            self._set_plugin_options('become', final_vars, templar, task_keys)
+
+            # FOR BACKWARDS COMPAT:
+            for option in ('become_user', 'become_flags', 'become_exe'):
+                try:
+                    setattr(self._play_context, option, self._connection.become.get_option(option))
+                except KeyError:
+                    pass  # some plugins don't support all base flags
+            self._play_context.prompt = self._connection.become.prompt
 
     def _get_action_handler(self, connection, templar):
         '''