feat(spec): disable cold/live migration for host maintenance strategy

Spec to:

- Add disable cold and live migraiton parameters to host maintenance strategy
- Add new stop instance action

Change-Id: Ic0291509f66b5a7bed016f0670206a39f27445ef

specs/2025.2/approved/host-maintenance-strategy-disable-migration.rst

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+..
+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+===========================================
+Host maintenance strategy disable migration
+===========================================
+
+Include the URL of your launchpad blueprint:
+
+https://blueprints.launchpad.net/watcher/+spec/example
+
+Problem description
+===================
+
+Host maintenance is a migration strategy designed for maintaining a compute
+node. It triggers either live or cold migration for all instances on the node,
+assuming that both migration methods are available. However, this may not apply
+to deployments where live or cold migration is not supported.
+
+Use Cases
+---------
+
+When using host maintenance strategy:
+
+- As a Cloud Administrator, if live migration is supported in my
+  OpenStack deployment. I want to apply live migration to the instance.
+- As a Cloud Administrator, if live migration is not supported in my
+  OpenStack deployment, but cold migration is supported.
+  I want to apply cold migration to the instance.
+- As a Cloud Administrator, if both live migration cold migration are
+  not supported in my OpenStack deployment.
+  I want to stop the instance.
+
+Proposed change
+===============
+
+Estimated changes are going to be in the following places:
+
+* Host maintenance strategy
+
+  * Input parameters **disable_cold_migration** and **disable_live_migration**
+    to disable the migration.
+
+  * If **disable_live_migration** is given:
+
+    * This tell the strategy the live migration shouldn't be considered
+      during planning.
+    * The instances in active status will be stopped.
+    * If **disable_cold_migration** is not given,
+      migrate all the SHUTOFF instances,
+      including the instances stopped by previous operation.
+
+  * If **disable_cold_migration** is given,
+    this tell the strategy the cold migration shouldn't be considered
+    during planning.
+
+* New stop actions in applier
+
+  * Action to stop the instance
+
+Alternatives
+------------
+
+None
+
+Data model impact
+-----------------
+
+None
+
+REST API impact
+---------------
+
+Two new input parameters for host maintenance strategy.
+
+Security impact
+---------------
+
+None
+
+Notifications impact
+--------------------
+
+None
+
+Other end user impact
+---------------------
+
+Two new input parameters for host maintenance strategy,
+the behavior is expected as the same if no parameters
+are provided, so no breaking change.
+
+Performance Impact
+------------------
+
+None
+
+Other deployer impact
+---------------------
+
+None
+
+Developer impact
+----------------
+
+None
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  <jneo8>
+
+Work Items
+----------
+
+1. New applier action to stop the instance.
+
+2. Modify the function which creates migration action for instance.
+
+Dependencies
+============
+
+* https://specs.openstack.org/openstack/watcher-specs/specs/queens/approved/cluster-maintenance-strategy.html
+
+Testing
+=======
+
+* Unit tests on the Watcher Decision Engine and Applier.
+
+* Integration tests
+
+  * Launch an audit with the **disable_live_migration**
+    input parameter enabled.
+  * Launch an audit with the **disable_cold_migration**
+    input parameter enabled.
+  * Launch an audit with both **disable_live_migration**,
+    **disable_cold_migration** input parameters enabled.
+
+Documentation Impact
+====================
+
+Need to update `Host Maintenance Strategy documentation`_.
+
+References
+==========
+
+None
+
+History
+=======
+
+None
+
+.. _Host Maintenance Strategy documentation: https://docs.openstack.org/watcher/latest/strategies/host_maintenance.html