Fix warning for nonexistent inventory cache (#72840)

* Fix inventory cache warning by checking if the key exists before loading it
* changelog

changelogs/fragments/inventory-cache-file-missing-warning.yaml

@@ -0,0 +1,2 @@
+minor_changes:
+  - inventory cache - do not show a warning when the cache file does not (yet) exist.

lib/ansible/plugins/cache/__init__.py

@@ -319,12 +319,13 @@ class CachePluginAdjudicator(MutableMapping):
 
     def _do_load_key(self, key):
         load = False
-        if key not in self._cache and key not in self._retrieved and self._plugin_name != 'memory':
-            if isinstance(self._plugin, BaseFileCacheModule):
-                load = True
-            elif not isinstance(self._plugin, BaseFileCacheModule) and self._plugin.contains(key):
-                # Database-backed caches don't raise KeyError for expired keys, so only load if the key is valid by checking contains()
-                load = True
+        if all([
+            key not in self._cache,
+            key not in self._retrieved,
+            self._plugin_name != 'memory',
+            self._plugin.contains(key),
+        ]):
+            load = True
         return load
 
     def __getitem__(self, key):

test/integration/targets/inventory_cache/aliases

@@ -0,0 +1 @@
+shippable/posix/group5

test/integration/targets/inventory_cache/cache_host.yml

@@ -0,0 +1,4 @@
+plugin: cache_host
+cache: true
+cache_plugin: jsonfile
+cache_connection: ./cache

test/integration/targets/inventory_cache/plugins/inventory/cache_host.py

@@ -0,0 +1,56 @@
+# Copyright (c) 2021 Ansible Project
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+
+DOCUMENTATION = '''
+    inventory: cache_host
+    short_description: add a host to inventory and cache it
+    description: add a host to inventory and cache it
+    extends_documentation_fragment:
+      - inventory_cache
+    options:
+      plugin:
+        required: true
+        description: name of the plugin (cache_host)
+'''
+
+from ansible.plugins.inventory import BaseInventoryPlugin, Cacheable
+import random
+
+
+class InventoryModule(BaseInventoryPlugin, Cacheable):
+
+    NAME = 'cache_host'
+
+    def verify_file(self, path):
+        if not path.endswith(('cache_host.yml', 'cache_host.yaml',)):
+            return False
+        return super(InventoryModule, self).verify_file(path)
+
+    def parse(self, inventory, loader, path, cache=None):
+        super(InventoryModule, self).parse(inventory, loader, path)
+        self._read_config_data(path)
+
+        cache_key = self.get_cache_key(path)
+        # user has enabled cache and the cache is not being flushed
+        read_cache = self.get_option('cache') and cache
+        # user has enabled cache and the cache is being flushed
+        update_cache = self.get_option('cache') and not cache
+
+        host = None
+        if read_cache:
+            try:
+                host = self._cache[cache_key]
+            except KeyError:
+                # cache expired
+                update_cache = True
+
+        if host is None:
+            host = 'testhost{0}'.format(random.randint(0, 50))
+
+        self.inventory.add_host(host, 'all')
+
+        if update_cache:
+            self._cache[cache_key] = host

test/integration/targets/inventory_cache/runme.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+
+set -eux
+
+export ANSIBLE_INVENTORY_PLUGINS=./plugins/inventory
+
+cleanup() {
+    for f in ./cache/ansible_inventory*; do
+	if [ -f "$f" ]; then rm -rf "$f"; fi
+    done
+}
+
+trap 'cleanup' EXIT
+
+# Test no warning when writing to the cache for the first time
+test "$(ansible-inventory -i cache_host.yml --graph 2>&1 | tee out.txt | grep -c '\[WARNING\]')" = 0
+writehost="$(grep "testhost[0-9]\{1,2\}" out.txt)"
+
+# Test reading from the cache
+test "$(ansible-inventory -i cache_host.yml --graph 2>&1 | tee out.txt | grep -c '\[WARNING\]')" = 0
+readhost="$(grep 'testhost[0-9]\{1,2\}' out.txt)"
+
+test "$readhost" = "$writehost"