Diffusion Scap 21715964342f

Support configuration for more serial group execution


Support configuration for more serial group execution

Tags: Release-Engineering-Team

Maniphest Tasks: T142990

Configuration of a global group_size or group-specific
{group}_group_size is now supported to achieve more serial deployments
to hosts within each server group. Each group affected by the
configuration will be split into smaller subgroups containing no more
hosts than the given size, and deployment stages will be executed
serially across each of the smaller subgroups.

Fixes T142990

Test Plan:
Tweak group_size globally and for a specific group and ensure
that deployment stages are executed for each smaller subgroup.

Reviewers: demon, mobrovac, mmodell, Release-Engineering-Team, thcipriani

Reviewed By: mobrovac, Release-Engineering-Team, thcipriani

Subscribers: jenkins

Differential Revision: https://phabricator.wikimedia.org/D321