Moar constructive (#28254)

* made composite vars and groups generic

now you can do both in every plugin that chooses to suport it
renamed constructed_groups as it now also constructs vars ... to constructed
moved most of constructed_groups logic into base class to easily share

* documented inventory_hostname

* typo fix

CHANGELOG.md

@@ -134,7 +134,7 @@ Ansible Changes By Release
 
 #### New Inventory Plugins:
 - advanced_host_list
-- constructed_groups
+- constructed
 - host_list
 - ini
 - script

examples/ansible.cfg

@@ -73,7 +73,7 @@
 #callback_whitelist = timer, mail
 
 # enable inventory plugins, default: 'host_list', 'script', 'yaml', 'ini'
-#inventory_enabled = host_list, aws, openstack, docker
+#inventory_enabled = host_list, virtualbox, yaml, constructed
 
 # Determine whether includes in tasks and handlers are "static" by
 # default. As of 2.0, includes are dynamic by default. Setting these

lib/ansible/plugins/inventory/__init__.py

@@ -50,6 +50,7 @@ class BaseInventoryPlugin(object):
 
         self.loader = loader
         self.inventory = inventory
+        self.templar = Templar(loader=loader)
 
     def verify_file(self, path):
         ''' Verify if file is usable by this plugin, base does minimal accessability check '''
@@ -81,9 +82,31 @@ class BaseInventoryPlugin(object):
 
     def _compose(self, template, variables):
         ''' helper method for pluigns to compose variables for Ansible based on jinja2 expression and inventory vars'''
-        t = Templar(loader=self.loader, variables=variables)
+        t = self.templar
+        t.set_available_variables(variables)
         return t.do_template('%s%s%s' % (t.environment.variable_start_string, template, t.environment.variable_end_string), disable_lookups=True)
 
+    def _set_composite_vars(self, compose, variables, host):
+        ''' loops over compose entries to create vars for hosts '''
+        if compose and isinstance(compose, dict):
+            for varname in compose:
+                composite = self._compose(compose[varname], variables)
+                self.inventory.set_variable(host, varname, composite)
+
+    def _add_host_to_composed_groups(self, groups, variables, host):
+        ''' helper to create complex groups for plugins based on jinaj2 conditionals, hosts that meet the conditional are added to group'''
+        # process each 'group entry'
+        if groups and isinstance(groups, dict):
+            self.templar.set_available_variables(variables)
+            for group_name in groups:
+                conditional = "{%% if %s %%} True {%% else %%} False {%% endif %%}" % groups[group_name]
+                result = self.templar.template(conditional)
+                if result and bool(result):
+                    # ensure group exists
+                    self.inventory.add_group(group_name)
+                    # add host to group
+                    self.inventory.add_child(group_name, host)
+
 
 class BaseFileInventoryPlugin(BaseInventoryPlugin):
     """ Parses a File based Inventory Source"""

lib/ansible/plugins/inventory/constructed.py

@@ -17,16 +17,28 @@
 #############################################
 '''
 DOCUMENTATION:
-    name: constructed_groups
+    name: constructed
     plugin_type: inventory
     version_added: "2.4"
-    short_description: Uses Jinja2 expressions to construct groups.
+    short_description: Uses Jinja2 to construct vars and groups based on existing inventory.
     description:
-        - Uses a YAML configuration file to identify group and the Jinja2 expressions that qualify a host for membership.
+        - Uses a YAML configuration file to define var expresisions and group conditionals
-        - Only variables already in inventory are available for expressions (no facts).
+        - The Jinja2 conditionals that qualify a host for membership.
+        - The JInja2 exprpessions are calculated and assigned to the variables
+        - Only variables already available from previous inventories can be used for templating.
         - Failed expressions will be ignored (assumes vars were missing).
+    compose:
+        description: create vars from jinja2 expressions
+        type: dictionary
+        default: {}
+    groups:
+        description: add hosts to group based on Jinja2 conditionals
+        type: dictionary
+        default: {}
 EXAMPLES: | # inventory.config file in YAML format
-    plugin: constructed_groups
+    plugin: comstructed
+    compose:
+        var_sum: var1 + var2
     groups:
         # simple name matching
         webservers: inventory_hostname.startswith('web')
@@ -48,15 +60,14 @@ import os
 
 from ansible.errors import AnsibleParserError
 from ansible.plugins.inventory import BaseInventoryPlugin
-from ansible.template import Templar
 from ansible.module_utils._text import to_native
 from ansible.utils.vars import combine_vars
 
 
 class InventoryModule(BaseInventoryPlugin):
-    """ constructs groups using Jinaj2 template expressions """
+    """ constructs groups and vars using Jinaj2 template expressions """
 
-    NAME = 'constructed_groups'
+    NAME = 'constructed'
 
     def __init__(self):
 
@@ -87,8 +98,6 @@ class InventoryModule(BaseInventoryPlugin):
             raise AnsibleParserError("%s is empty or not a constructed groups config file" % (to_native(path)))
 
         try:
-            templar = Templar(loader=loader)
-
             # Go over hosts (less var copies)
             for host in inventory.hosts:
 
@@ -96,16 +105,12 @@ class InventoryModule(BaseInventoryPlugin):
                 hostvars = inventory.hosts[host].get_vars()
                 if host in inventory.cache:  # adds facts if cache is active
                     hostvars = combine_vars(hostvars, inventory.cache[host])
-                templar.set_available_variables(hostvars)
 
-                # process each 'group entry'
+                # create composite vars
-                for group_name in data.get('groups', {}):
+                self._set_composite_vars(data.get('compose'), hostvars, host)
-                    conditional = u"{%% if %s %%} True {%% else %%} False {%% endif %%}" % data['groups'][group_name]
+
-                    result = templar.template(conditional)
+                # constructed groups based on conditionals
-                    if result and bool(result):
+                self._add_host_to_composed_groups(data.get('groups'), hostvars, host)
-                        # ensure group exists
+
-                        inventory.add_group(group_name)
-                        # add host to group
-                        inventory.add_child(group_name, host)
         except Exception as e:
             raise AnsibleParserError("failed to parse %s: %s " % (to_native(path), to_native(e)))

lib/ansible/plugins/inventory/virtualbox.py

@@ -24,6 +24,7 @@ DOCUMENTATION:
     description:
         - Get inventory hosts from the local virtualbox installation.
         - Uses a <name>.vbox.yaml (or .vbox.yml) YAML configuration file.
+        - The inventory_hostname is always the 'Name' of the virtualbox instance.
     options:
         running_only:
             description: toggles showing all vms vs only those currently running
@@ -42,6 +43,10 @@ DOCUMENTATION:
             description: create vars from jinja2 expressions, these are created AFTER the query block
             type: dictionary
             default: {}
+        groups:
+            description: add hosts to group based on Jinja2 conditionals, these also run after query block
+            type: dictionary
+            default: {}
 EXAMPLES:
 # file must be named vbox.yaml or vbox.yml
 simple_config_file:
@@ -94,14 +99,15 @@ class InventoryModule(BaseInventoryPlugin):
                     hostvars[host][varname] = self._query_vbox_data(host, data['query'][varname])
 
             # create composite vars
-            if data.get('compose') and isinstance(data['compose'], dict):
+            self._set_composite_vars(data.get('compose'), hostvars, host)
-                for varname in data['compose']:
-                    hostvars[host][varname] = self._compose(data['compose'][varname], hostvars[host])
 
             # actually update inventory
             for key in hostvars[host]:
                 self.inventory.set_variable(host, key, hostvars[host][key])
 
+            # constructed groups based on conditionals
+            self._add_host_to_composed_groups(data.get('groups'), hostvars, host)
+
     def _populate_from_source(self, source_data, config_data):
         hostvars = {}
         prevkey = pref_k = ''