Updating without downtime

To avoid service unavailability, you can update an instance group by creating additional instances with a new configuration.

As you add instances with a new configuration to the group, the instances with the old configuration are deleted.

To do this:

1. Define the desired template of an instance.
2. Set the deployment policy with a non-zero value of max_expansion: the maximum number of additionally created instances.
3. Run the update operation for the group.

For example, to update a group using the algorithm described, set the following parameters in the deploy-policy:

...
deploy-policy:
    max_unavailable = 0
    max_expansion = 1
    ...
...

The group will be updated as follows: