[Task] Define the env app min and max scaling values

What should be done

Define the scale max and min limits for an app environment in order to let the creator keep the control on it and do not have billing surprises.

The default min is 0.

The default max is 5.

Technical recommandation

When the min is defined to 0, the app is scaled to 0 only when the environment stops (all the socket session for this env are closed). It scales to 1 when the env starts. See this PR for more informations: https://github.com/lenra-io/application-runner/pull/358. When the min is higher than 0, the app never scales to 0.

The max can't be lower than 1 nor the min limit.

We'll use the OpenFaaS limits labels to handle this.

The scaling limits are saved in the database.

Ecological concerns

When the user chose to define the min higher than 0, we should warn him.

Is this task linked with any other ?

Linked to https://github.com/lenra-io/application-runner/issues/357

Blocked by:

• https://github.com/lenra-io/server/issues/410