First implementation of 'fallback' parameter

Implemented & documented for EOS & NXOS

lib/ansible/module_utils/basic.py

@@ -516,6 +516,18 @@ def is_executable(path):
             or stat.S_IXOTH & os.stat(path)[stat.ST_MODE])
 
 
+class AnsibleFallbackNotFound(Exception):
+    pass
+
+def env_fallback(*args, **kwargs):
+    ''' Load value from environment '''
+    for arg in args:
+        if arg in os.environ:
+            return os.environ[arg]
+    else:
+        raise AnsibleFallbackNotFound
+
+
 class AnsibleModule(object):
     def __init__(self, argument_spec, bypass_checks=False, no_log=False,
         check_invalid_arguments=True, mutually_exclusive=None, required_together=None,
@@ -550,6 +562,7 @@ class AnsibleModule(object):
 
         self._load_constants()
         self._load_params()
+        self._set_fallbacks()
 
         # append to legal_inputs and then possibly check against them
         try:
@@ -1421,6 +1434,23 @@ class AnsibleModule(object):
                 if k not in self.params:
                     self.params[k] = default
 
+    def _set_fallbacks(self):
+        for k,v in self.argument_spec.items():
+            fallback = v.get('fallback', (None,))
+            fallback_strategy = fallback[0]
+            fallback_args = []
+            fallback_kwargs = {}
+            if k not in self.params and fallback_strategy is not None:
+                for item in fallback[1:]:
+                    if isinstance(item, dict):
+                        fallback_kwargs = item
+                    else:
+                        fallback_args = item
+                try:
+                    self.params[k] = fallback_strategy(*fallback_args, **fallback_kwargs)
+                except AnsibleFallbackNotFound:
+                    continue
+
     def _load_params(self):
         ''' read the input and set the params attribute'''
         if MODULE_COMPLEX_ARGS is None:

lib/ansible/module_utils/eos.py

@@ -20,7 +20,7 @@ import os
 
 import re
 
-from ansible.module_utils.basic import AnsibleModule
+from ansible.module_utils.basic import AnsibleModule, env_fallback
 from ansible.module_utils.shell import Shell, Command, HAS_PARAMIKO
 from ansible.module_utils.netcfg import parse
 from ansible.module_utils.urls import fetch_url
@@ -30,24 +30,16 @@ NET_PASSWD_RE = re.compile(r"[\r\n]?password: $", re.I)
 NET_COMMON_ARGS = dict(
     host=dict(required=True),
     port=dict(type='int'),
-    username=dict(required=True),
-    password=dict(no_log=True),
-    ssh_keyfile=dict(type='path'),
-    authorize=dict(default=False, type='bool'),
-    auth_pass=dict(no_log=True),
+    username=dict(fallback=(env_fallback, ['ANSIBLE_NET_USERNAME'])),
+    password=dict(no_log=True, fallback=(env_fallback, ['ANSIBLE_NET_PASSWORD'])),
+    ssh_keyfile=dict(fallback=(env_fallback, ['ANSIBLE_NET_SSH_KEYFILE']), type='path'),
+    authorize=dict(default=False, fallback=(env_fallback, ['ANSIBLE_NET_AUTHORIZE']), type='bool'),
+    auth_pass=dict(no_log=True, fallback=(env_fallback, ['ANSIBLE_NET_AUTH_PASS'])),
     transport=dict(default='cli', choices=['cli', 'eapi']),
     use_ssl=dict(default=True, type='bool'),
     provider=dict(type='dict')
 )
 
-NET_ENV_ARGS = dict(
-    username='ANSIBLE_NET_USERNAME',
-    password='ANSIBLE_NET_PASSWORD',
-    ssh_keyfile='ANSIBLE_NET_SSH_KEYFILE',
-    authorize='ANSIBLE_NET_AUTHORIZE',
-    auth_pass='ANSIBLE_NET_AUTH_PASS',
-)
-
 CLI_PROMPTS_RE = [
     re.compile(r"[\r\n]?[\w+\-\.:\/\[\]]+(?:\([^\)]+\)){,3}(?:>|#) ?$"),
     re.compile(r"\[\w+\@[\w\-\.]+(?: [^\]])\] ?[>#\$] ?$")
@@ -200,9 +192,6 @@ class NetworkModule(AnsibleModule):
             if key in NET_COMMON_ARGS:
                 if self.params.get(key) is None and value is not None:
                     self.params[key] = value
-        for key, env_var in NET_ENV_ARGS.items():
-            if self.params.get(key) is None and env_var in os.environ:
-                self.params[key] = os.environ[env_var]
 
     def connect(self):
         try:

lib/ansible/module_utils/nxos.py

@@ -21,7 +21,7 @@ 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
+from ansible.module_utils.basic import AnsibleModule, env_fallback
 from ansible.module_utils.netcfg import parse
 
 NET_PASSWD_RE = re.compile(r"[\r\n]?password: $", re.I)
@@ -29,8 +29,9 @@ NET_PASSWD_RE = re.compile(r"[\r\n]?password: $", re.I)
 NET_COMMON_ARGS = dict(
     host=dict(required=True),
     port=dict(type='int'),
-    username=dict(required=True),
-    password=dict(no_log=True),
+    username=dict(fallback=(env_fallback, ['ANSIBLE_NET_USERNAME'])),
+    password=dict(no_log=True, fallback=(env_fallback, ['ANSIBLE_NET_PASSWORD'])),
+    ssh_keyfile=dict(fallback=(env_fallback, ['ANSIBLE_NET_SSH_KEYFILE']), type='path'),
     transport=dict(default='cli', choices=['cli', 'nxapi']),
     use_ssl=dict(default=False, type='bool'),
     validate_certs=dict(default=True, type='bool'),
@@ -165,11 +166,11 @@ class Cli(object):
 
         username = self.module.params['username']
         password = self.module.params['password']
+        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.open(host, port=port, username=username, password=password)
+            self.shell = Shell(prompts_re=CLI_PROMPTS_RE, errors_re=CLI_ERRORS_RE, kickstart=False)
+            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))
             self.module.fail_json(msg=msg)