Check controlpersist (#17443)

* Add a new config option to cache the check for controlpersist on the
control machine.

Fixes #15844

* Remove the option and make the behavior the default

* Make the check for controlpersist cache its status per-ssh executable

lib/ansible/executor/playbook_executor.py

@@ -28,6 +28,7 @@ from ansible.playbook import Playbook
 from ansible.template import Templar
 from ansible.utils.helpers import pct_to_int
 from ansible.utils.path import makedirs_safe
+from ansible.utils.ssh_functions import check_for_controlpersist
 
 try:
     from __main__ import display
@@ -57,6 +58,14 @@ class PlaybookExecutor:
         else:
             self._tqm = TaskQueueManager(inventory=inventory, variable_manager=variable_manager, loader=loader, options=options, passwords=self.passwords)
 
+        # Note: We run this here to cache whether the default ansible ssh
+        # executable supports control persist.  Sometime in the future we may
+        # need to enhance this to check that ansible_ssh_executable specified
+        # in inventory is also cached.  We can't do this caching at the point
+        # where it is used (in task_executor) because that is post-fork and
+        # therefore would be discarded after every task.
+        check_for_controlpersist(C.ANSIBLE_SSH_EXECUTABLE)
+
     def run(self):
 
         '''

lib/ansible/executor/task_executor.py

@@ -36,6 +36,7 @@ from ansible.playbook.task import Task
 from ansible.template import Templar
 from ansible.utils.encrypt import key_for_hostname
 from ansible.utils.listify import listify_lookup_plugin_terms
+from ansible.utils.ssh_functions import check_for_controlpersist
 from ansible.vars.unsafe_proxy import UnsafeProxy, wrap_var
 
 try:
@@ -666,14 +667,7 @@ class TaskExecutor:
                 conn_type = "paramiko"
             else:
                 # see if SSH can support ControlPersist if not use paramiko
-                try:
+                if not check_for_controlpersist(self._play_context.ssh_executable):
-                    ssh_executable = C.ANSIBLE_SSH_EXECUTABLE
-                    cmd = subprocess.Popen([ssh_executable, '-o', 'ControlPersist'], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-                    (out, err) = cmd.communicate()
-                    err = to_text(err)
-                    if u"Bad configuration option" in err or u"Usage:" in err:
-                        conn_type = "paramiko"
-                except OSError:
                     conn_type = "paramiko"
 
         connection = self._shared_loader_obj.connection_loader.get(conn_type, self._play_context, self._new_stdin)

lib/ansible/inventory/__init__.py

@@ -21,6 +21,7 @@ __metaclass__ = type
 
 import fnmatch
 import os
+import subprocess
 import sys
 import re
 import itertools

lib/ansible/utils/ssh_functions.py

@@ -0,0 +1,47 @@
+# (c) 2016, James Tanner
+# (c) 2016, Toshio Kuratomi <tkuratomi@ansible.com>
+#
+# This file is part of Ansible
+#
+# Ansible is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Ansible is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
+
+# Make coding more python3-ish
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+
+import subprocess
+
+
+_HAS_CONTROLPERSIST = {}
+
+
+def check_for_controlpersist(ssh_executable):
+    try:
+        # If we've already checked this executable
+        return _HAS_CONTROLPERSIST[ssh_executable]
+    except KeyError:
+        pass
+
+    has_cp = True
+    try:
+        cmd = subprocess.Popen([ssh_executable,'-o','ControlPersist'], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        (out, err) = cmd.communicate()
+        if b"Bad configuration option" in err or b"Usage:" in err:
+            has_cp = False
+    except OSError:
+        has_cp = False
+
+    _HAS_CONTROLPERSIST[ssh_executable] = has_cp
+    return has_cp
+