Hi Zoubayer,

When launching instances, you can add user-data, I would add cloud-init script to launch after instance is created.

Create a file with cloud-init configuration and add --user-data while creating the instance.

Please, check this blog post which explains more in deep this process.

https://raymii.org/s/tutorials/Automa...

With Horizon you can add the script at Configuration tab.

Customization Script Source

Specify a customization script that runs after your instance launches.

Regards