How to dynamically create digital ocean droplets without password change? I am working on a web app where that I divided into two blocks:
1. One for front-end.
2. One for backend doingheavy computation which won't be used every time
Both parts of the web service are hosted on digital ocean.
In order to cut costs, I created manually a snapshot of the back. The idea is to create a droplet from this image using a rest API if required by the front. At the start of the backend droplet, two docker containers are created immediately.

My problem is that since the droplet is a fresh ubuntu instance, my cron jobs are not executed after the creation of the droplet. 
I am suspecting the reason is because Ubuntu is asking for password change and blocking every thing.

For that, I need to rechange the password of the instance manually then reboot it. This is clearly not possible.
Is there a way to automate this part ?
After more tests, I found out that in order to do this, I need to use an ssh key with the API. The password change phase is bypassed after this.