avoid constant checking controlpersist (#69910)

* avoid constant checking controlpersist

changelogs/fragments/only_be_smart_once.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - optimize 'smart' detection from being run over and over and preferably do it at config time.

lib/ansible/config/base.yml

@@ -135,7 +135,7 @@ ANSIBLE_SSH_CONTROL_PATH_DIR:
   - {key: control_path_dir, section: ssh_connection}
   yaml: {key: ssh_connection.control_path_dir}
 ANSIBLE_SSH_EXECUTABLE:
-  # TODO: move to ssh plugin
+  # TODO: move to ssh plugin, note that ssh_utils  refs this and needs to be updated if removed
   default: ssh
   description:
     - This defines the location of the ssh binary. It defaults to `ssh` which will use the first ssh binary available in $PATH.
@@ -1162,6 +1162,7 @@ DEFAULT_TIMEOUT:
   - {key: timeout, section: defaults}
   type: integer
 DEFAULT_TRANSPORT:
+  # note that ssh_utils refs this and needs to be updated if removed
   name: Connection plugin
   default: smart
   description: "Default connection plugin to use, the 'smart' option will toggle between 'ssh' and 'paramiko' depending on controller OS and ssh versions"

lib/ansible/constants.py

@@ -12,11 +12,11 @@ from ast import literal_eval
 from jinja2 import Template
 from string import ascii_letters, digits
 
+from ansible.config.manager import ConfigManager, ensure_type, get_ini_config_value
 from ansible.module_utils._text import to_text
 from ansible.module_utils.common.collections import Sequence
 from ansible.module_utils.parsing.convert_bool import boolean, BOOLEANS_TRUE
 from ansible.module_utils.six import string_types
-from ansible.config.manager import ConfigManager, ensure_type, get_ini_config_value
 
 
 def _warning(msg):

lib/ansible/executor/playbook_executor.py

@@ -31,7 +31,7 @@ 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
+from ansible.utils.ssh_functions import set_default_transport
 from ansible.utils.display import Display
 
 display = Display()
@@ -70,7 +70,7 @@ class PlaybookExecutor:
         # 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)
+        set_default_transport()
 
     def run(self):
         '''

lib/ansible/utils/ssh_functions.py

@@ -22,7 +22,9 @@ __metaclass__ = type
 
 import subprocess
 
+from ansible import constants as C
 from ansible.module_utils._text import to_bytes
+from ansible.module_utils.compat.paramiko import paramiko
 
 
 _HAS_CONTROLPERSIST = {}
@@ -47,3 +49,17 @@ def check_for_controlpersist(ssh_executable):
 
     _HAS_CONTROLPERSIST[ssh_executable] = has_cp
     return has_cp
+
+
+def set_default_transport():
+
+    # deal with 'smart' connection .. one time ..
+    if C.DEFAULT_TRANSPORT == 'smart':
+        # TODO: check if we can deprecate this as ssh w/o control persist should
+        # not be as common anymore.
+
+        # see if SSH can support ControlPersist if not use paramiko
+        if not check_for_controlpersist(C.ANSIBLE_SSH_EXECUTABLE) and paramiko is not None:
+            C.DEFAULT_TRANSPORT = "paramiko"
+        else:
+            C.DEFAULT_TRANSPORT = "ssh"