Allow delegate_to if transport is not cli (#29945)

Fixes #29060

Allow delegate_to if transport is either nxapi or eapi.

Persistent connection uses `cli` transport and create
a local socket on control node. Hence delegate_to is not allowed
for `cli` transport.

However as `nxapi` and `eapi` transport does not use persistent connection
it is possible to use delegate_to in this case.

docs/docsite/rst/porting_guide_2.3.rst

@@ -213,10 +213,10 @@ Will result in:
 delegate_to vs ProxyCommand
 ---------------------------
 
-The new connection framework for Network Modules in Ansible 2.3 no longer supports the use of the
-``delegate_to`` directive.  In order to use a bastion or intermediate jump host
-to connect to network devices, network modules now support the use of
-``ProxyCommand``.
+The new connection framework for Network Modules in Ansible 2.3 that uses ``cli`` transport
+no longer supports the use of the ``delegate_to`` directive.
+In order to use a bastion or intermediate jump host to connect to network devices over ``cli``
+transport, network modules now support the use of ``ProxyCommand``.
 
 To use ``ProxyCommand`` configure the proxy settings in the Ansible inventory
 file to specify the proxy host.

lib/ansible/plugins/action/eos.py

@@ -37,16 +37,16 @@ except ImportError:
 class ActionModule(_ActionModule):
 
     def run(self, tmp=None, task_vars=None):
-        if self._play_context.connection != 'local':
+        provider = load_provider(eos_provider_spec, self._task.args)
+        transport = provider['transport'] or 'cli'
+
+        if self._play_context.connection != 'local' and transport == 'cli':
             return dict(
                 failed=True,
                 msg='invalid connection specified, expected connection=local, '
                     'got %s' % self._play_context.connection
             )
 
-        provider = load_provider(eos_provider_spec, self._task.args)
-        transport = provider['transport'] or 'cli'
-
         display.vvvv('connection transport is %s' % transport, self._play_context.remote_addr)
 
         if transport == 'cli':

lib/ansible/plugins/action/nxos.py

@@ -37,16 +37,16 @@ except ImportError:
 class ActionModule(_ActionModule):
 
     def run(self, tmp=None, task_vars=None):
-        if self._play_context.connection != 'local':
+        provider = load_provider(nxos_provider_spec, self._task.args)
+        transport = provider['transport'] or 'cli'
+
+        if self._play_context.connection != 'local' and transport == 'cli':
             return dict(
                 failed=True,
                 msg='invalid connection specified, expected connection=local, '
                     'got %s' % self._play_context.connection
             )
 
-        provider = load_provider(nxos_provider_spec, self._task.args)
-        transport = provider['transport'] or 'cli'
-
         display.vvvv('connection transport is %s' % transport, self._play_context.remote_addr)
 
         if transport == 'cli':