Documentation related to Instance lease feature

source/adminguide/service_offerings.rst

@@ -401,6 +401,33 @@ To create a new compute offering:
          -  **Disk Offering Strictness**: This flag defines the strictness of the disk offering association 
             with the compute offering. When set to true, overriding of disk offering is not allowed on deploy instance
             and change disk offering is not allowed for the ROOT disk
+
+   -  **Enable Lease**: When this flag is enabled, compute offering is created with lease related metadata.
+      In CloudStack, a lease represents the specific duration for which an instance is allocated.
+      The user rents these resources for the duration of the lease. Once the lease period expires, instance may be stopped or destroyed.
+      Lease information is inherited from compute offering and gets associated to Instance.
+
+      .. note:: The global configuration ``instance.lease.enabled`` should be configured as true to create compute offering with lease.
+
+         ``instance.lease.enabled``: Indicates whether Instance Lease feature is enabled or not. Default is **false**
+         For more information, see `“Setting Global Configuration Parameters”
+         <../installguide/configuration.html#setting-global-configuration-parameters>`_.
+
+      When the flag is enabled
+
+         -  **Lease Duration (in days)**: Creates a compute offering with Lease duration. Instance created from this compute offering will inherit lease duration by default.
+
+         -  **Lease expiry action**: Denotes lease expiry action, which gets executed upon lease expiry for instances created from compute offering.
+            Suported values for lease expiry action are as follows:
+
+            - STOP
+            - DESTROY
+
+   .. image:: /_static/images/compute_offering_dailog_with_lease.png
+      :width: 400px
+      :align: center
+      :alt: Compute offering dialog box
+
 
 #. Click Add.
 

source/adminguide/virtual_machines.rst

@@ -960,6 +960,146 @@ restoreVirtualMachine call. In this case, the Instance's root disk is
 destroyed and recreated, but from the same Template or ISO that was
 already in use by the Instance.
 
+Instance Lease
+--------------
+
+Cloudstack provides capability to create instance on lease. Lease denotes a set period for which resource is allocated and upon expiry cleanup is performed.
+This feature enables automated cleanup of instances created for specific duration and for specific purpose. This feature gives administrators the ability to automatically reclaim
+resources that are no longer needed by expired virtual machines, helping to optimize resource utilization and reduce wastage.
+
+
+**Configuring lease feature**
+
+The cloud administrator can use global configuration variables to control the behavior of Instance Lease.
+To set these variables, API or CloudStack UI can be used:
+
+======================================= ========================
+Configuration                            Description
+======================================= ========================
+instance.lease.enabled                   Indicates whether to enable the Instance lease featuew, will be applicable only on instances created after lease is enabled. **Default: false**
+instance.lease.scheduler.interval		  Background task interval in seconds that executes Lease expiry action on eligibile expired instances. Default: 3600.
+instance.lease.alertscheduler.interval	  Background task interval in seconds that executes Lease alert for instances about to be expired in next N days. Default: 86400
+instance.lease.alert.daysbefore          Denotes number of days (N) for alert task. Default: 7 days
+======================================= ========================
+
+
+**Lease Parameters**
+
+
+**leaseduration**: Lease duration is specified in days. This can take Natural numbers and -1 to disable the lease.
+
+Lease may require to be disabled in following scenarios:
+
+- During deployment of instance while using compute offering with lease metadata
+- Edit instance with existing lease
+
+**leaseexpiryaction**: There are two expiry action supported:
+
+- STOP: The instance is stopped, and it will be out of lease. The user can restart the instance manually.
+- DESTROY: The instance is destroyed when the lease expires.
+
+.. note:: Expiry action is executed at most once on the instance, e.g. STOP action will bring instance in Stoppped state on expiry and instance will be out of lease. User may choose to start it again.
+
+
+**Using Instance Lease**
+
+Lease information is associated to an Instance and following parameters are used to enable lease for it:
+
+#. leaseduration
+#. leaseexpiryaction
+
+Instance remains active for specified leaseduration (in days). Upon lease expiry, configured expiryaction is executed on the instance and 
+lease is removed from the instance for any further action.
+
+**Notes:**
+
+#. Lease Assignment: A lease can only be assigned to an instance during deployment.
+#. Lease Acquisition: Instances without a lease cannot acquire one by switching to a different compute offering or by editing the instance.
+#. Lease Inheritance: Instances inherit the lease from a compute offering that contains lease metadata. This lease can be overridden or disabled in the "Advanced Settings".
+#. Lease Persistence: A lease is always tied to the instance. Modifications to the compute offering do not affect the instance's lease.
+#. Non-Lease Compute offering: Instances can have a lease by enabling it in the "Advanced Settings" for non-lease based compute offering too.
+#. Lease Duration Management: The lease duration can be extended or reduced for instances before expiry. However, once the lease is disabled, it cannot be re-enabled for that instance.
+#. Lease Expiry: Once the lease expires and the associated action is completed, the lease is annulled and cannot be reattached or extended.
+#. Feature Disablement: If the lease feature is disabled, the lease associated with instances is canceled. Re-enabling the feature will not automatically reapply the lease to previously grandfathered instances.
+#. Delete Protection: The DESTROY lease expiry action is skipped for instances with delete protection enabled.
+
+**Deployment of Instance with lease**
+
+There are 2 ways to deploy instance with lease from UI:
+
+1. Use compute offering which has associated lease metadata for instance
+
+.. image:: /_static/images/deploy_instance_lease_offering.png
+   :width: 400px
+   :align: center
+   :alt: Deploy Instance with lease compute offering dialog box
+
+2. Enable lease under Advance settings during instance Deployment
+
+.. image:: /_static/images/deploy_instance_advanced_lease.png
+   :width: 400px
+   :align: center
+   :alt: Deploy Instance with lease using advance settings
+
+
+**Using API**
+
+Pass lease parameters in the command to enable lease during instance deployment:
+
+.. code:: bash
+
+   cmk deploy virtualmachine name=..... leaseduration=... leaseexpiryaction=...
+
+- Use compute offering with lease
+
+.. code:: bash
+
+   cmk deploy virtualmachine name=..... serviceofferingid=lease-compute-offering
+
+
+**Editing Instance Lease**
+
+The lease duration for an instance can be extended, reduced, or disabled for instances that already have an active lease.
+However, it is not possible to enable the lease on an instance after it has already been deployed.
+
+From UI:
+
+.. image:: /_static/images/edit_instance_lease.png
+   :width: 400px
+   :align: center
+   :alt: Edit Instance lease dialog
+
+
+Using API:
+
+.. code:: bash
+
+   cmk update virtualmachine id=fa970d19-8340-455c-a9fb-569205954fdc leaseduration=20 leaseexpiryaction=DESTROY
+
+To disable lease using API:
+
+.. code:: bash
+
+   cmk update virtualmachine id=fa970d19-8340-455c-a9fb-569205954fdc leaseduration=-1
+
+.. note:: DESTORY action will ignore instance if deleteprotection is enabled for it.
+
+.. note:: When the feature is disabled, the lease associated with instances is cancelled. Re-enabling the feature will not automatically reapply the lease to previously grandfathered instances.
+
+
+**Instance Lease Events**
+
+Lease feature generates various events to help in auditing and monitoring:
+
+=================== ========================
+Event Type           Description
+=================== ========================
+VM.LEASE.EXPIRED	   Event is generated at lease expiry
+VM.LEASE.DISABLED	   Denotes if lease is disabled by user/admin
+VM.LEASE.CANCELLED   When lease is cancelled (feature gets disabled)
+VM.LEASE.EXPIRING	   Expiry intimation event for instance
+=================== ========================
+
 
 Advanced Instance Settings
 --------------------------