Allow ansible_ssh_args to be set as an inventory variable

Before this change, ssh_args could be set only in the [ssh_connection]
section of ansible.cfg, and was applied to all hosts. Now it's possible
to set ansible_ssh_args as an inventory variable (directly, or through
group_vars or host_vars) to selectively override the global setting.

Note that the default ControlPath settings are applied only if ssh_args
is not set, and this is true of ansible_ssh_args as well. So if you want
to override ssh_args but continue to set ControlPath, you'll need to
repeat the appropriate options when setting ansible_ssh_args.

(If you only need to add options to the default ssh_args, you may be
able to use the ansible_ssh_extra_args inventory variable instead.)

docsite/rst/intro_inventory.rst

@@ -211,9 +211,11 @@ SSH connection::
       The ssh password to use (this is insecure, we strongly recommend using --ask-pass or SSH keys)
     ansible_ssh_private_key_file
       Private key file used by ssh.  Useful if using multiple keys and you don't want to use SSH agent.
+    ansible_ssh_args
+      This setting overrides any ``ssh_args`` configured in ``ansible.cfg``.
     ansible_ssh_extra_args
       Additional arguments for ssh. Useful to configure a ``ProxyCommand`` for a certain host (or group).
-      This is used in addition to any ``ssh_args`` configured in ``ansible.cfg``.
+      This is used in addition to any ``ssh_args`` configured in ``ansible.cfg`` or the inventory.
 
 Privilege escalation (see :doc:`Ansible Privilege Escalation<become>` for further details)::
 

lib/ansible/plugins/connections/ssh.py

@@ -59,11 +59,14 @@ class Connection(ConnectionBase):
 
         self.host = self._play_context.remote_addr
         self.ssh_extra_args = ''
+        self.ssh_args = ''
 
     def set_host_overrides(self, host):
         v = host.get_vars()
         if 'ansible_ssh_extra_args' in v:
             self.ssh_extra_args = v['ansible_ssh_extra_args']
+        if 'ansible_ssh_args' in v:
+            self.ssh_args = v['ansible_ssh_args']
 
     @property
     def transport(self):
@@ -78,10 +81,10 @@ class Connection(ConnectionBase):
         if self._connected:
             return self
 
-        extra_args = C.ANSIBLE_SSH_ARGS
+        ssh_args = self.ssh_args or C.ANSIBLE_SSH_ARGS
-        if extra_args is not None:
+        if ssh_args is not None:
             # make sure there is no empty string added as this can produce weird errors
-            self._common_args += [x.strip() for x in shlex.split(extra_args) if x.strip()]
+            self._common_args += [x.strip() for x in shlex.split(ssh_args) if x.strip()]
         else:
             self._common_args += (
                 "-o", "ControlMaster=auto",