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.

Example of a YAML file entry:

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

Keys:

Strategies 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 an opportunistic strategy, Instance Groups doesn't stop the instances, but waits until at least one of the following conditions are met:

• The user stopped an instance in Compute Cloud.
• The application or user stopped the instance internally.
• The instance failed the application health check.

For example, you created an instance group with automatic scaling based on the custom metric of the number of jobs in the queue. Instance Groups creates an instance group that executes the jobs from the queue. As soon as the queue runs out of jobs, Instance Groups must reduce the group size from the actual size to the target size according to the scaling policy.

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

Example of a YAML file entry:

...
deploy_policy:
    strategy: OPPORTUNISTIC
...

Keys: