fixes bug where setting state=absent in nxos_nxapi is not idempotent (#4984)

When setting state=absent the nxos_nxapi module would always try to remove
the configuration regardless of the current state of the device.  This will
fix that problem.

This also updates the docstring to correctly reflect https as default=no

fixes #4955
depends on ansible/ansible#17728

lib/ansible/modules/network/nxos/nxos_nxapi.py

@@ -65,7 +65,7 @@ options:
         enable the use of the HTTPS transport, set the value of this
         argument to True.
     required: false
-    default: yes
+    default: no
     choices: ['yes', 'no']
     aliases: ['enable_https']
   sandbox:
@@ -151,7 +151,26 @@ def invoke(name, *args, **kwargs):
     if func:
         return func(*args, **kwargs)
 
-def present(module, commands):
+def get_instance(module):
+    instance = dict(state='absent')
+    try:
+        resp = module.cli('show nxapi', 'json')
+    except NetworkError:
+        return instance
+
+    instance['state'] = 'present'
+
+    instance['http'] = 'http_port' in resp[0]
+    instance['http_port'] = resp[0].get('http_port') or 80
+
+    instance['https'] = 'https_port' in resp[0]
+    instance['https_port'] = resp[0].get('https_port') or 443
+
+    instance['sandbox'] = resp[0]['sandbox_status']
+
+    return instance
+
+def present(module, instance, commands):
     commands.append('feature nxapi')
     setters = set()
     for key, value in module.argument_spec.iteritems():
@@ -159,12 +178,13 @@ def present(module, commands):
         if setter not in setters:
             setters.add(setter)
             if module.params[key] is not None:
-                invoke(setter, module, commands)
+                invoke(setter, module, instance, commands)
 
-def absent(module, commands):
-    commands.append('no feature nxapi')
+def absent(module, instance, commands):
+    if instance['state'] != 'absent':
+        commands.append('no feature nxapi')
 
-def set_http(module, commands):
+def set_http(module, instance, commands):
     port = module.params['http_port']
     if not 0 <= port <= 65535:
         module.fail_json(msg='http_port must be between 1 and 65535')
@@ -173,7 +193,7 @@ def set_http(module, commands):
     elif module.params['http'] is False:
         commands.append('no nxapi http')
 
-def set_https(module, commands):
+def set_https(module, instance, commands):
     port = module.params['https_port']
     if not 0 <= port <= 65535:
         module.fail_json(msg='https_port must be between 1 and 65535')
@@ -182,7 +202,7 @@ def set_https(module, commands):
     elif module.params['https'] is False:
         commands.append('no nxapi https')
 
-def set_sandbox(module, commands):
+def set_sandbox(module, instance, commands):
     if module.params['sandbox'] is True:
         commands.append('nxapi sandbox')
     elif module.params['sandbox'] is False:
@@ -287,7 +307,9 @@ def main():
                         'a future release.  Please use state=absent instead')
 
     commands = list()
-    invoke(state, module, commands)
+    instance = get_instance(module)
+
+    invoke(state, module, instance, commands)
 
     try:
         load(module, commands, result)