Improve boto profile handling for EC2 inventory (#20280)

Ensure command line profile argument and AWS_PROFILE environment variable
overrides config file
Remove unnecessary `lambda` function
Fix cache file path construction to be more pythonic (and windows-ready)

contrib/inventory/ec2.py

@@ -340,8 +340,8 @@ class Ec2Inventory(object):
         else:
             self.all_elasticache_nodes = False
 
-        # boto configuration profile (prefer CLI argument)
-        self.boto_profile = self.args.boto_profile
+        # boto configuration profile (prefer CLI argument then environment variables then config file)
+        self.boto_profile = self.args.boto_profile or os.environ.get('AWS_PROFILE')
         if config.has_option('ec2', 'boto_profile') and not self.boto_profile:
             self.boto_profile = config.get('ec2', 'boto_profile')
 
@@ -376,14 +376,11 @@ class Ec2Inventory(object):
             os.makedirs(cache_dir)
 
         cache_name = 'ansible-ec2'
-        aws_profile = lambda: (self.boto_profile or
-                               os.environ.get('AWS_PROFILE') or
-                               os.environ.get('AWS_ACCESS_KEY_ID') or
-                               self.credentials.get('aws_access_key_id', None))
-        if aws_profile():
-            cache_name = '%s-%s' % (cache_name, aws_profile())
-        self.cache_path_cache = cache_dir + "/%s.cache" % cache_name
-        self.cache_path_index = cache_dir + "/%s.index" % cache_name
+        cache_id = self.boto_profile or os.environ.get('AWS_ACCESS_KEY_ID', self.credentials.get('aws_access_key_id'))
+        if cache_id:
+            cache_name = '%s-%s' % (cache_name, cache_id)
+        self.cache_path_cache = os.path.join(cache_dir, "%s.cache" % cache_name)
+        self.cache_path_index = os.path.join(cache_dir, "%s.index" % cache_name)
         self.cache_max_age = config.getint('ec2', 'cache_max_age')
 
         if config.has_option('ec2', 'expand_csv_tags'):