DigitalOcean - Fix TypeError when users have tags named the same as droplets (#41368)

* Fix TypeError when users have tags named the same as droplets
* Updated code based on review comments

contrib/inventory/digital_ocean.py

@@ -429,6 +429,21 @@ class DigitalOceanInventory(object):
             self.data['tags'] = self.manager.all_tags()
             self.cache_refreshed = True
 
+    def add_inventory_group(self, key):
+        """ Method to create group dict """
+        host_dict = {'hosts': [], 'vars': {}}
+        self.inventory[key] = host_dict
+        return
+
+    def add_host(self, group, host):
+        """ Helper method to reduce host duplication """
+        if group not in self.inventory:
+            self.add_inventory_group(group)
+
+        if host not in self.inventory[group]['hosts']:
+            self.inventory[group]['hosts'].append(host)
+        return
+
     def build_inventory(self):
         """ Build Ansible inventory of droplets """
         self.inventory = {
@@ -449,8 +464,9 @@ class DigitalOceanInventory(object):
 
             self.inventory['all']['hosts'].append(dest)
 
-            self.inventory[droplet['id']] = [dest]
+            self.add_host(droplet['id'], dest)
-            self.inventory[droplet['name']] = [dest]
+
+            self.add_host(droplet['name'], dest)
 
             # groups that are always present
             for group in ('digital_ocean',
@@ -459,24 +475,18 @@ class DigitalOceanInventory(object):
                           'size_' + droplet['size']['slug'],
                           'distro_' + DigitalOceanInventory.to_safe(droplet['image']['distribution']),
                           'status_' + droplet['status']):
-                if group not in self.inventory:
+                self.add_host(group, dest)
-                    self.inventory[group] = {'hosts': [], 'vars': {}}
-                self.inventory[group]['hosts'].append(dest)
 
             # groups that are not always present
             for group in (droplet['image']['slug'],
                           droplet['image']['name']):
                 if group:
                     image = 'image_' + DigitalOceanInventory.to_safe(group)
-                    if image not in self.inventory:
+                    self.add_host(image, dest)
-                        self.inventory[image] = {'hosts': [], 'vars': {}}
-                    self.inventory[image]['hosts'].append(dest)
 
             if droplet['tags']:
                 for tag in droplet['tags']:
-                    if tag not in self.inventory:
+                    self.add_host(tag, dest)
-                        self.inventory[tag] = {'hosts': [], 'vars': {}}
-                    self.inventory[tag]['hosts'].append(dest)
 
             # hostvars
             info = self.do_namespace(droplet)