relax api payload and accept custom input

[norman shen]

After this commit https://review.opendev.org/#/c/626541/, masakari api will reject payload which does not confirm to pre-defined schema.

I think it is better to relax this constraint and allow additional parameters. For example, we are analysing uing prometheus-alertmanager to deliver alerts to masakari-api and create custom task flow to handle them. But I am worried that since payload format is pretty strict, I am not able to pass useful information to task flows.

So I am suggesting relax constraints and allow additional parameters.

[Tushar Patil (tpatil)]

Against which notification type you want to pass the alert information?

You can also resolve this issue by adding a new notification type where you can relax payload. You will need to propose a new blueprint in order to add a new notification type.