# tower callbacks **URL:** \ **Category:** Ansible Project\ **Created:** [November 26, 2014, 2:42pm UTC](https://forum.ansible.com/t/tower-callbacks/16894 "2014-11-26T14:42:00Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Levi\_Notik](https://avatars.discourse-cdn.com/v4/letter/l/4491bb/32.png) [@Levi\_Notik](https://forum.ansible.com/u/Levi_Notik)\ **Post date:** [November 26, 2014, 2:42pm UTC](https://forum.ansible.com/t/tower-callbacks/16894/1 "2014-11-26T14:42:00Z")
I created a simple playbook to test this out and I baked an AMI which curls the callback endpoint on startup (added as user data). If my inventory needs to contain the instance that triggers the callback, how does that happen if, by definition, the machine that’s just coming online is not in my inventory? Does the request to the callback endpoint trigger an inventory sync? Also, after debugging this for a bit, I’m seeing that the response from the callback endpoint is {“msg”:“No matching host could be found”}. Any ideas? ---
**Author:** ![Levi\_Notik](https://avatars.discourse-cdn.com/v4/letter/l/4491bb/32.png) [@Levi\_Notik](https://forum.ansible.com/u/Levi_Notik)\ **Post date:** [November 26, 2014, 2:54pm UTC](https://forum.ansible.com/t/tower-callbacks/16894/2 "2014-11-26T14:54:25Z")
I figured this out. Looks like I had issues with the security group for my tower instance. ---
**Author:** ![James\_Martin1](https://avatars.discourse-cdn.com/v4/letter/j/0ea827/32.png) [@James\_Martin1](https://forum.ansible.com/u/James_Martin1)\ **Post date:** [November 26, 2014, 3:01pm UTC](https://forum.ansible.com/t/tower-callbacks/16894/3 "2014-11-26T15:01:57Z")
Levi, Please send Tower support requests to [support@ansible.com](mailto:support@ansible.com) in the future. To answer your question, the call back request will indeed trigger an inventory sync if the host that is calling back is not found in the inventory. Thanks, James