Feature/add ansible play hosts all (#17498)

* refactor ignore_limits_and_restrictions

into ignore_limits and ignore_limitations

* add ansible_play_hosts_all

* update docs re ansible_play_hosts_all

* only use play.hosts when is has a value

* replace ansible_play_hosts with ansible_play_hosts_all

* remove unnecessary var

5 files changed, 24 insertions, 27 deletions

diff --git a/docsite/rst/playbooks_delegation.rst b/docsite/rst/playbooks_delegation.rst
index eaddbf3608..5731f13ddb 100644
--- a/docsite/rst/playbooks_delegation.rst
+++ b/docsite/rst/playbooks_delegation.rst
@@ -224,7 +224,7 @@ This approach is similar to applying a conditional to a task such as::
 .. note::
      When used together with "serial", tasks marked as "run_once" will be run on one host in *each* serial batch.
      If it's crucial that the task is run only once regardless of "serial" mode, use
-     :code:`inventory_hostname == my_group_name[0]` construct.
+     :code:`when: inventory_hostname == ansible_play_hosts[0]` construct.
 
 .. _local_playbooks:
 
diff --git a/docsite/rst/playbooks_variables.rst b/docsite/rst/playbooks_variables.rst
index 25247ddbd5..774e9423bd 100644
--- a/docsite/rst/playbooks_variables.rst
+++ b/docsite/rst/playbooks_variables.rst
@@ -674,6 +674,7 @@ reasons.  If you have a long FQDN, ``inventory_hostname_short`` also contains th
 period, without the rest of the domain.
 
 ``play_hosts`` is available as a list of hostnames that are in scope for the current play. This may be useful for filling out templates with multiple hostnames or for injecting the list into the rules for a load balancer.
+``ansible_play_hosts`` is the same as ``play_hosts`` but includes all hosts in all ``serial`` batches, if you're not using ``serial`` it's the same as ``play_hosts``.
 
 Don't worry about any of this unless you think you need it.  You'll know when you do.
 
diff --git a/lib/ansible/inventory/__init__.py b/lib/ansible/inventory/__init__.py
index a6ce377366..14c18b711b 100644
--- a/lib/ansible/inventory/__init__.py
+++ b/lib/ansible/inventory/__init__.py
@@ -165,7 +165,7 @@ class Inventory(object):
             self.get_group_vars(group)
 
         # get host vars from host_vars/ files and vars plugins
-        for host in self.get_hosts(ignore_limits_and_restrictions=True):
+        for host in self.get_hosts(ignore_limits=True, ignore_restrictions=True):
             host.vars = combine_vars(host.vars, self.get_host_variables(host.name))
             self.get_host_vars(host)
 
@@ -193,7 +193,7 @@ class Inventory(object):
                 results.append(item)
         return results
 
-    def get_hosts(self, pattern="all", ignore_limits_and_restrictions=False):
+    def get_hosts(self, pattern="all", ignore_limits=False, ignore_restrictions=False):
         """
         Takes a pattern or list of patterns and returns a list of matching
         inventory host names, taking into account any active restrictions
@@ -206,11 +206,11 @@ class Inventory(object):
         else:
             pattern_hash = pattern
 
-        if not ignore_limits_and_restrictions:
-            if self._subset:
-                pattern_hash += u":%s" % to_text(self._subset)
-            if self._restriction:
-                pattern_hash += u":%s" % to_text(self._restriction)
+        if not ignore_limits and self._subset:
+            pattern_hash += u":%s" % to_text(self._subset)
+
+        if not ignore_restrictions and self._restriction:
+            pattern_hash += u":%s" % to_text(self._restriction)
 
         if pattern_hash not in HOSTS_PATTERNS_CACHE:
 
@@ -218,15 +218,14 @@ class Inventory(object):
             hosts = self._evaluate_patterns(patterns)
 
             # mainly useful for hostvars[host] access
-            if not ignore_limits_and_restrictions:
+            if not ignore_limits and self._subset:
                 # exclude hosts not in a subset, if defined
-                if self._subset:
-                    subset = self._evaluate_patterns(self._subset)
-                    hosts = [ h for h in hosts if h in subset ]
+                subset = self._evaluate_patterns(self._subset)
+                hosts = [ h for h in hosts if h in subset ]
 
+            if not ignore_restrictions and self._restriction:
                 # exclude hosts mentioned in any restriction (ex: failed hosts)
-                if self._restriction:
-                    hosts = [ h for h in hosts if h.name in self._restriction ]
+                hosts = [ h for h in hosts if h.name in self._restriction ]
 
             seen = set()
             HOSTS_PATTERNS_CACHE[pattern_hash] = [x for x in hosts if x not in seen and not seen.add(x)]
diff --git a/lib/ansible/vars/__init__.py b/lib/ansible/vars/__init__.py
index d10e4b81a8..e333e348b1 100644
--- a/lib/ansible/vars/__init__.py
+++ b/lib/ansible/vars/__init__.py
@@ -413,9 +413,8 @@ class VariableManager:
                 # DEPRECATED: play_hosts should be deprecated in favor of ansible_play_hosts,
                 #             however this would take work in the templating engine, so for now
                 #             we'll add both so we can give users something transitional to use
-                host_list = [x.name for x in self._inventory.get_hosts()]
-                variables['play_hosts'] = host_list
-                variables['ansible_play_hosts'] = host_list
+                variables['play_hosts'] = [x.name for x in self._inventory.get_hosts()]
+                variables['ansible_play_hosts'] = [x.name for x in self._inventory.get_hosts(pattern=play.hosts or 'all', ignore_restrictions=True)]
 
         # the 'omit' value alows params to be left out if the variable they are based on is undefined
         variables['omit'] = self._omit_token
@@ -490,7 +489,7 @@ class VariableManager:
                     if delegated_host_name in C.LOCALHOST:
                         delegated_host = self._inventory.localhost
                     else:
-                        for h in self._inventory.get_hosts(ignore_limits_and_restrictions=True):
+                        for h in self._inventory.get_hosts(ignore_limits=True, ignore_restrictions=True):
                             # check if the address matches, or if both the delegated_to host
                             # and the current host are in the list of localhost aliases
                             if h.address == delegated_host_name:
diff --git a/lib/ansible/vars/hostvars.py b/lib/ansible/vars/hostvars.py
index 31d30ad801..36adf54906 100644
--- a/lib/ansible/vars/hostvars.py
+++ b/lib/ansible/vars/hostvars.py
@@ -20,19 +20,17 @@ from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
 import collections
-import sys
 
 from jinja2 import Undefined as j2undefined
 
 from ansible import constants as C
-from ansible.inventory.host import Host
 from ansible.template import Templar
 
 STATIC_VARS = [
-  'inventory_hostname', 'inventory_hostname_short',
-  'inventory_file', 'inventory_dir', 'playbook_dir',
-  'ansible_play_hosts', 'play_hosts', 'groups', 'ungrouped', 'group_names',
-  'ansible_version', 'omit', 'role_names'
+    'inventory_hostname', 'inventory_hostname_short',
+    'inventory_file', 'inventory_dir', 'playbook_dir',
+    'ansible_play_hosts', 'play_hosts', 'groups',
+    'ungrouped', 'group_names', 'ansible_version', 'omit', 'role_names'
 ]
 
 try:
@@ -103,15 +101,15 @@ class HostVars(collections.Mapping):
         return self._find_host(host_name) is not None
 
     def __iter__(self):
-        for host in self._inventory.get_hosts(ignore_limits_and_restrictions=True):
+        for host in self._inventory.get_hosts(ignore_limits=True, ignore_restrictions=True):
             yield host
 
     def __len__(self):
-        return len(self._inventory.get_hosts(ignore_limits_and_restrictions=True))
+        return len(self._inventory.get_hosts(ignore_limits=True, ignore_restrictions=True))
 
     def __repr__(self):
         out = {}
-        for host in self._inventory.get_hosts(ignore_limits_and_restrictions=True):
+        for host in self._inventory.get_hosts(ignore_limits=True, ignore_restrictions=True):
             name = host.name
             out[name] = self.get(name)
         return repr(out)