Deployment policy

When creating an instance group, you can choose how the instances will be deployed in the group.

The deployment policy is a set of restrictions defined in the deploy_policy key in the YAML file. Each restriction is set in its own key as a key-value pair.

Here is how a YAML file entry may look like:

...
deploy_policy:
    max_creating: 10
    max_deleting: 10
    max_unavailable: 10
    max_expansion: 0
    startup_duration: 30s
...

Where:

Strategies for stopping instancesStrategies for stopping instances

Instance Groups supports two strategies for stopping instances when updating or automatically scaling a group: PROACTIVE and OPPORTUNISTIC.

If a proactive strategy is selected, Instance Groups selects which instances to stop on its own.

With the opportunistic strategy, Instance Groups, rather than stopping the instances, will wait until at least one of the following conditions are met:

• User stops an instance in Compute Cloud.
• Application or user stops the instance internally.
• Instance fails the application health check.

For example, let's assume you created an instance group with automatic scaling based on the custom metric of the number of jobs in the queue. Instance Groups will create an instance group to run the jobs from the queue. As soon as there are no more jobs, Instance Groups must reduce the group size from the actual size to the target one according to the scaling policy.

• If you selected proactive stop, Instance Groups will change the target group size and decrease the actual number of instances in the group to the target amount.
• Under the opportunistic strategy, Instance Groups will change the target group size, but will not stop the instances until they are stopped by themselves or by the user.

Here is how a YAML file entry may look like:

...
deploy_policy:
    strategy: OPPORTUNISTIC
...

Where: