Clarify exception handling in net modules (#15507)

* Clarify exception handling in EOS

Also modify to EOS to standardize modules. It makes vimdiff a lot less angry

* Move IOS exception handling into Cli

* Move IOS-XR exception handling into Cli

* Move JUNOS exception handling into Cli

* Move NXOS exception handling into Cli

And reorganize to make it match the other modules

* Move OpenSwitch exception handling into Cli

More speculative restructuring here

lib/ansible/module_utils/nxos.py

@@ -19,10 +19,10 @@
 
 import re
 
-from ansible.module_utils.urls import fetch_url
-from ansible.module_utils.shell import Shell, HAS_PARAMIKO
-from ansible.module_utils.basic import AnsibleModule, env_fallback
+from ansible.module_utils.basic import AnsibleModule, env_fallback, get_exception
+from ansible.module_utils.shell import Shell, ShellError, HAS_PARAMIKO
 from ansible.module_utils.netcfg import parse
+from ansible.module_utils.urls import fetch_url
 
 NET_PASSWD_RE = re.compile(r"[\r\n]?password: $", re.I)
 
@@ -60,6 +60,7 @@ CLI_ERRORS_RE = [
     re.compile(r"unknown command")
 ]
 
+
 def to_list(val):
     if isinstance(val, (list, tuple)):
         return list(val)
@@ -68,6 +69,7 @@ def to_list(val):
     else:
         return list()
 
+
 class Nxapi(object):
 
     def __init__(self, module):
@@ -169,14 +171,19 @@ class Cli(object):
         key_filename = self.module.params['ssh_keyfile']
 
         try:
-            self.shell = Shell(prompts_re=CLI_PROMPTS_RE, errors_re=CLI_ERRORS_RE, kickstart=False)
+            self.shell = Shell(kickstart=False, prompts_re=CLI_PROMPTS_RE, errors_re=CLI_ERRORS_RE)
             self.shell.open(host, port=port, username=username, password=password, key_filename=key_filename)
-        except Exception, exc:
-            msg = 'failed to connect to %s:%s - %s' % (host, port, str(exc))
+        except ShellError:
+            e = get_exception()
+            msg = 'failed to connect to %s:%s - %s' % (host, port, str(e))
             self.module.fail_json(msg=msg)
 
     def send(self, commands, encoding='text'):
-        return self.shell.send(commands)
+        try:
+            return self.shell.send(commands)
+        except ShellError:
+            e = get_exception()
+            self.module.fail_json(msg=e.message, commands=commands)
 
 
 class NetworkModule(AnsibleModule):
@@ -201,15 +208,17 @@ class NetworkModule(AnsibleModule):
         super(NetworkModule, self)._load_params()
         provider = self.params.get('provider') or dict()
         for key, value in provider.items():
-            if key in NET_COMMON_ARGS.keys():
+            if key in NET_COMMON_ARGS:
                 if self.params.get(key) is None and value is not None:
                     self.params[key] = value
 
     def connect(self):
-        if self.params['transport'] == 'nxapi':
-            self.connection = Nxapi(self)
-        else:
-            self.connection = Cli(self)
+        cls = globals().get(str(self.params['transport']).capitalize())
+        try:
+            self.connection = cls(self)
+        except TypeError:
+            e = get_exception()
+            self.fail_json(msg=e.message)
 
         self.connection.connect()
 
@@ -218,6 +227,12 @@ class NetworkModule(AnsibleModule):
 
         self._connected = True
 
+    def configure(self, commands):
+        commands = to_list(commands)
+        if self.params['transport'] == 'cli':
+            return self.configure_cli(commands)
+        else:
+            return self.execute(commands, command_type='cli_conf')
 
     def configure_cli(self, commands):
         commands = to_list(commands)
@@ -226,13 +241,6 @@ class NetworkModule(AnsibleModule):
         responses.pop(0)
         return responses
 
-    def configure(self, commands):
-        commands = to_list(commands)
-        if self.params['transport'] == 'cli':
-            return self.configure_cli(commands)
-        else:
-            return self.execute(commands, command_type='cli_conf')
-
     def execute(self, commands, **kwargs):
         if not self.connected:
             self.connect()
@@ -240,6 +248,7 @@ class NetworkModule(AnsibleModule):
 
     def disconnect(self):
         self.connection.close()
+        self._connected = False
 
     def parse_config(self, cfg):
         return parse(cfg, indent=2)
@@ -262,7 +271,6 @@ def get_module(**kwargs):
 
     module = NetworkModule(**kwargs)
 
-    # HAS_PARAMIKO is set by module_utils/shell.py
     if module.params['transport'] == 'cli' and not HAS_PARAMIKO:
         module.fail_json(msg='paramiko is required but does not appear to be installed')