adds feature to try to auto determine network_os (#18674)

This updates the network_cli connection plugin to attempt to automatically
determine the remote device os.  The device network os discovery can
be overridden by setting the ansible_network_os value.

lib/ansible/plugins/connection/network_cli.py

@@ -39,14 +39,8 @@ class Connection(_Connection):
     def __init__(self, play_context, new_stdin, *args, **kwargs):
         super(Connection, self).__init__(play_context, new_stdin, *args, **kwargs)
 
-        assert self._play_context.network_os, 'ansible_network_os must be set'
-
-        self._terminal = terminal_loader.get(self._play_context.network_os, self)
-        if not self._terminal:
-            raise AnsibleConnectionFailure('network os %s is not supported' % self._play_context.network_os)
-
+        self._terminal = None
         self._shell = None
-
         self._matched_prompt = None
         self._matched_pattern = None
         self._last_response = None
@@ -64,6 +58,24 @@ class Connection(_Connection):
 
     def _connect(self):
         super(Connection, self)._connect()
+
+        network_os = self._play_context.network_os
+        if not network_os:
+            for cls in terminal_loader.all(class_only=True):
+                network_os = cls.guess_network_os(self.ssh)
+                if network_os:
+                    break
+
+        if not network_os:
+            raise AnsibleConnectionFailure(
+                'unable to determine device network os.  Please configure '
+                'ansible_network_os value'
+            )
+
+        self._terminal = terminal_loader.get(network_os, self)
+        if not self._terminal:
+            raise AnsibleConnectionFailure('network os %s is not supported' % network_os)
+
         return (0, 'connected', '')
 
     def open_shell(self, timeout=10):

lib/ansible/plugins/terminal/__init__.py

@@ -69,3 +69,6 @@ class TerminalBase(with_metaclass(ABCMeta, object)):
     def on_deauthorize(self):
         pass
 
+    @staticmethod
+    def guess_network_os(conn):
+        pass

lib/ansible/plugins/terminal/eos.py

@@ -79,4 +79,9 @@ class TerminalModule(TerminalBase):
         elif prompt.endswith('#'):
             self._exec_cli_command('disable')
 
+    @staticmethod
+    def guess_network_os(conn):
+        stdin, stdout, stderr = conn.exec_command('show version')
+        if 'Arista' in stdout.read():
+            return 'eos'
 

lib/ansible/plugins/terminal/ios.py

@@ -80,3 +80,9 @@ class TerminalModule(TerminalBase):
             self._exec_cli_command('disable')
 
 
+    @staticmethod
+    def guess_network_os(conn):
+        stdin, stdout, stderr = conn.exec_command('show version')
+        if 'Cisco IOS Software' in stdout.read():
+            return 'ios'
+

lib/ansible/plugins/terminal/iosxr.py

@@ -52,4 +52,10 @@ class TerminalModule(TerminalBase):
         except AnsibleConnectionFailure:
             raise AnsibleConnectionFailure('unable to set terminal parameters')
 
+    @staticmethod
+    def guess_network_os(conn):
+        stdin, stdout, stderr = conn.exec_command('show version')
+        if 'Cisco IOS XR' in stdout.read():
+            return 'iosxr'
+
 

lib/ansible/plugins/terminal/junos.py

@@ -45,3 +45,9 @@ class TerminalModule(TerminalBase):
         except AnsibleConnectionFailure:
             raise AnsibleConnectionFailure('unable to set terminal parameters')
 
+    @staticmethod
+    def guess_network_os(conn):
+        stdin, stdout, stderr = conn.exec_command('show version')
+        if 'Junos' in stdout.read():
+            return 'junos'
+

lib/ansible/plugins/terminal/nxos.py

@@ -52,5 +52,11 @@ class TerminalModule(TerminalBase):
         except AnsibleConnectionFailure:
             raise AnsibleConnectionFailure('unable to set terminal parameters')
 
+    @staticmethod
+    def guess_network_os(conn):
+        stdin, stdout, stderr = conn.exec_command('show version')
+        if 'NX-OS' in stdout.read():
+            return 'nxos'
+
 
 

lib/ansible/plugins/terminal/vyos.py

@@ -44,4 +44,9 @@ class TerminalModule(TerminalBase):
         except AnsibleConnectionFailure:
             raise AnsibleConnectionFailure('unable to set terminal parameters')
 
+    @staticmethod
+    def guess_network_os(conn):
+        stdin, stdout, stderr = conn.exec_command('cat /proc/version')
+        if 'vyos' in stdout.read():
+            return 'vyos'