Add Promise userguide

This patch adds a first draft of the Promise userguide. Let's aim to
review and merge this draft asap and then use separate patches to fix
editorial issues and update the content.

JIRA: PROMISE-64

Change-Id: I891895938d115a327362d0297304a30390728435
Signed-off-by: Gerald Kunzmann <kunzmann@docomolab-euro.com>

1 files changed, 394 insertions, 4 deletions

diff --git a/docs/userguide/userguide.rst b/docs/userguide/userguide.rst
index e337adf..1485273 100644
--- a/docs/userguide/userguide.rst
+++ b/docs/userguide/userguide.rst
@@ -1,5 +1,395 @@
-==================
-Promise User Guide
-==================
+Promise capabilities and usage
+==============================
 
-Promise user guide documentation.
+Promise is a resource reservation and management project to identify NFV related
+requirements and realize resource reservation for future usage by capacity
+management of resource pools regarding compute, network and storage.
+
+The following are the key features provided by this module:
+
+* Capacity Management
+* Reservation Management
+* Allocation Management
+
+The Brahmaputra implementation of Promise is built with the YangForge data
+modeling framework [#f2]_ , using a shim-layer on top of OpenStack to provide
+the Promise features. This approach requires communication between
+Consumers/Administrators and OpenStack to pass through the shim-layer. The
+shim-layer intercepts the message flow to manage the allocation requests based
+on existing reservations and available capacities in the providers. It also
+extracts information from the intercepted messages in order to update its
+internal databases. Furthermore, Promise provides additional intent-based APIs
+to allow a Consumer or Administrator to perform capacity management (i.e. add
+providers, update the capacity, and query the current capacity and utilization
+of a provider), reservation management (i.e. create, update, cancel, query
+reservations), and allocation management (i.e. create, destroy, query
+instances).
+
+Detailed information about Promise use cases, features, interface
+specifications, work flows, and the underlying Promise YANG schema can be found
+in the Promise requirement document [#f1]_ .
+
+
+Promise usage
+-------------
+
+The yfc run command will load the primary application package from this
+repository along with any other dependency files/assets referenced within the
+YAML manifest and instantiate the opnfv-promise module and run REST/JSON
+interface by default listeningon port 5000.::
+    $ yfc run promise.yaml
+
+
+You can also checkout the GIT repository (https://github.com/opnfv/promise/) or
+simply download the files into your local system and run the application.
+
+
+Promise feature and API usage guidelines and examples
+-----------------------------------------------------
+
+This section lists the Promise features and API implemented in OPNFV Brahmaputra.
+
+
+Note 1: In contrast to ETSI NFV specifications and the detailed interface
+specification in Section 7, the Promise shim-layer implementation does not
+distinguish intent interfaces per resource type, i.e. the various capacity,
+reservations, etc. operations have different endpoints for each domain such as
+compute, storage, and network. The current shim-layer implementation does not
+separate the endpoints for performing the various operations.
+
+Note 2: The listed parameters are optional unless explicitly marked as
+"mandatory".
+
+
+Reservation management
+^^^^^^^^^^^^^^^^^^^^^^
+
+The reservation management allows a Consumer to request reservations for
+resource capacity or specific resource elements. Reservations can be for now or
+a later time window. After the start time of a reservation has arrived, the
+Consumer can issue create server instance requests against the reserved
+capacity / elements. Note, a reservation will expire after a predefined
+*expiry* time in case no allocation referring to the reservation is requested.
+
+The implemented workflow is well aligned with the described workflow in the
+Promise requirement document [#f1]_ (Clause 6.1) except for the
+"multi-provider" scenario as described in :ref:`multi-provider` .
+
+.. _create-reservation:
+
+*create-reservation*
+""""""""""""""""""""
+
+This operation allows making a request to the reservation system to reserve
+resources. The Consumer can either request to reserve a certain capacity
+(*container*) or specific resource elements (*elements*), like a certain server
+instance.
+
+The operation takes the following input parameters:
+
+* start: start time of the requested reservation
+* end: end time of the requested reservation
+* container: request for reservation of capacity
+
+  * instances: number of instances
+  * cores: number of cores
+  * ram: size of ram (in MB)
+  * networks: number of networks
+  * addresses: number of (public) IP addresses
+  * ports: number of ports
+  * routers: number of routers
+  * subnets: number of subnets
+  * gigabytes: size of storage (in GB)
+  * volumes: number of volumes
+  * snapshots: number of snapshots
+
+* elements: reference to a list of 'pre-existing' resource elements that are
+  required for fulfillment of the resource-usage-request
+
+  * instance-identifier: identifier of a specific resource element
+
+* zone: identifier of an Availability Zone
+
+Promise will check the available capacity in the given time window and in case
+sufficient capacity exists to meet the reservation request, will mark those
+resources "reserved" in its reservation map.
+
+
+*update-reservation*
+""""""""""""""""""""
+
+This operation allows to update the reservation details for an existing
+reservation.
+
+It can take the same input parameters as in *create-reservation*
+but in addition requires a mandatory reference to the *reservation-id* of the
+reservation that shall be updated.
+
+
+*cancel-reservation*
+""""""""""""""""""""
+
+This operation is used to cancel an existing reservation.
+
+The operation takes the following input parameter:
+
+* reservation-id (mandatory): identifier of the reservation to be canceled.
+
+
+*query-reservation*
+"""""""""""""""""""
+
+The operation queries the reservation system to return reservation(s) matching
+the specified query filter, e.g., reservations that are within a specified
+start/end time window.
+
+The operation takes the following input parameters to narrow down the query
+results:
+
+* zone: identifier of an Availability Zone
+* without: excludes specified collection identifiers from the result
+* elements:
+
+  * some: query for ResourceCollection(s) that contain some or more of these
+    element(s)
+  * every: query for ResourceCollection(s) that contain all of these
+    element(s)
+
+* window: matches entries that are within the specified start/end time window
+
+  * start: start time
+  * end: end time
+  * scope: if set to 'exclusive', only reservations with start AND end time
+    within the time window are returned. Otherwise ('inclusive'), all
+    reservation starting OR ending in the time windows are returned.
+
+* show-utilization: boolean value that specifies whether to also return the
+  resource utilization in the queried time window or not
+
+
+*subscribe-reservation-events* / *notify-reservation-events*
+""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+Subscription to receive notifications about reservation-related events, e.g. a
+reservation is about to expire or a reservation is in conflict state due to a
+failure in the NFVI.
+
+Note, this feature is not yet available in Brahmaputra release.
+
+
+
+Allocation management
+^^^^^^^^^^^^^^^^^^^^^
+
+*create-instance*
+"""""""""""""""""
+
+This operation is used to create an instance of specified resource(s) for
+immediate use utilizing capacity from the pool. *Create-instance* requests can
+be issued against an existing reservation, but also allocations without a
+reference to an existing reservation are allowed. In case the allocation
+request specifies a reservation identifier, Promise checks if a reservation
+with that ID exists, the reservation start time has arrived (i.e. the
+reservation is 'active'), and the required capacity for the requested flavor is
+within the available capacity of the reservation. If those conditions are met,
+Promise creates a record for the allocation (VMState="INITIALIZED") and update
+its databases. If no *reservation_id* was provided in the allocation request,
+Promise checks whether the required capacity to meet the request can be
+provided from the available, non-reserved capacity. If yes, Promise creates a
+record for the allocation with an unique *instance-id* and update its
+databases. In any other case, Promise rejects the *create-instance* request.
+
+In case the *create-instance* request is rejected, Promise responds with a
+"status=rejected" providing the reason of the rejection. This will help the
+Consumer to take appropriate actions, e.g., send an updated *create-instance*
+request. In case the *create-instance* request was accepted and a related
+allocation record has been created, the shim-layer issues a *createServer*
+request to the VIM Controller providing all information to create the server
+instance.
+
+The operation takes the following input parameters:
+
+* name (mandatory): Assigned name for the instance to be created
+* image (mandatory): the image to be booted in the new instance
+* flavor (mandatory): the flavor of the requested server instance
+* provider-id: identifier of the provider where the instance shall be created
+* reservation-id: identifier of a resource reservation the *create-instance*
+  is issued against
+
+The Brahamputra implementation of Promise has the following limitations:
+
+* All create server instance requests shall pass through the Promise
+  shim-layer such that Promise can keep track of all allocation requests. This
+  is necessary as in the current release the sychronization between the VIM
+  Controller and Promise on the available capacity is not yet implemented.
+* *Create-allocation* requests are limited to "simple" allocations, i.e., the
+  current workflow only supports the Nova compute service and
+  *create-allocation* requests are limited to creating one server instance at a
+  time
+* Prioritization of reservations and allocations is yet not implemented.
+  Future version may allow certain policy-based conflict resolution where,
+  e.g., new allocation request with high priority can "forcefully" terminate
+  lower priority allocations.
+
+
+*destroy-instance*
+""""""""""""""""""
+
+This operation request to destroy an existing server instance and release it
+back to the pool.
+
+The operation takes the following input parameter:
+
+* instance-id: identifier of the server instance to be destroyed
+
+
+*query-resource-collection*
+"""""""""""""""""""""""""""
+
+This operation allows to query for resource collection(s) that are within the
+specified start/end time window.
+
+
+*subscribe-allocation-events* / *notify-allocation-events*
+""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+Subscription to receive notifications about allocation-related events, e.g. an
+allocation towards the VIM that did not pass the Promise shim-layer
+
+Note, this feature is not yet available in Brahmaputra release.
+
+
+
+Capacity management
+^^^^^^^^^^^^^^^^^^^
+
+The capacity management feature allows the Consumer or Administrator to do
+capacity planning, i.e. the capacity available to the reservation management
+can differ from the actual capacity in the registered provider(s). This feature
+can, e.g., be used to limit the available capacity for a given time window due
+to a planned downtime of some of the resources, or increase the capacity
+available to the reservation system in case of a plannes upgrade of the
+available capacity.
+
+*increase/decrease-capacity*
+""""""""""""""""""""""""""""
+
+This operations allows to increase/decrease the total capacity that is made
+available to the Promise reservation service between a specified window in
+time. It does NOT increase the actual capacity of a given resource provider,
+but is used for capacity management inside Promise.
+
+This feature can be used in different ways, like
+
+* Limit the capacity available to the reservation system to a value below 100%
+  of the available capacity in the VIM, e.g., in order to leave "buffer" in the
+  actual NFVI to be used outside the Promise reservation service.
+
+* Inform the reservation system that, from a given time in the future,
+  additional resources can be reserved, e.g., due to a planned upgrade of the
+  available capacity of the provider.
+
+* Similarily, the "decrease-capacity" can be used to reduce the consumable
+  resources in a given time window, e.g., to prepare for a planned downtime of
+  some of the resources.
+
+* Expose multiple reservation service instances to different consumers sharing
+  the same resource provider.
+
+The operation takes the following input parameters:
+
+* start: start time for the increased/decreased capacity
+
+* end: end time for the increased/decreased capacity
+
+* container: see :ref:`create-reservation`
+
+Note, increase/decreasing the capacity in Promise is completely transparent to
+the VIM. As such, when increasing the virtual capacity in Promise (e.g. for a
+planned upgrade of the capacity), it is in the responsibility of the
+Consumer/Administrator to ensure sufficient resources in the VIM are available
+at the appropriate time, in order to prevent allocations against reservations
+to fail due to a lack of resources. Therefore, this operations should only be
+used carefully.
+
+
+*query-capacity*
+""""""""""""""""
+
+This operation is used to query the available capacity information of the
+specified resource collection. A filter attribute can be specified to narrow
+down the query results.
+
+The current implementation supports the following filter criteria:
+
+* time window: returns reservations matching the specified window
+
+* window scope: if set to 'exclusive', only reservations with start AND end time
+  within the time window are returned. Otherwise, all reservation starting OR
+  ending in the time windows are returned.
+
+* metric: query for one of the following capacity metrics:
+
+  * 'total': resource pools
+  * 'reserved': reserved resources
+  * 'usage': resource allocations
+  * 'available': remaining capacity, i.e. neither reserved nor allocated
+
+
+*subscribe-capacity-events* / *notify-capacity-events*
+""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+These operations enable the Consumer to subscribe to receiving notifications
+about capacity-related events, e.g., increased/decreased capacity for a
+provider due to a failure or upgrade of a resource pool. In order to provide
+such notifications to its Consumers, Promise shim-layer has to subscribe itself
+to OpenStack Aodh to be notified from the VIM about any capacity related events.
+
+Note, this feature is not yet available in Brahmaputra release.
+
+
+.. _multi-provider:
+
+(Multi-)provider management
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This API  towards OpenStack allows an Consumer/Administrator to add and remove
+resource providers to Promise. Note, Promise supports a multi-provider
+configuration, however, for Brahmaputra, multi-provider support is not yet
+fully supported.
+
+*add-provider*
+""""""""""""""
+
+This operation is used to register a new resource provider into the Promise
+reservation system.
+
+Note, for Brahmaputra, the add-provider operation should only be used to
+register one provider with the Promise shim-layer. Further note that currently
+only OpenStack is supported as a provider.
+
+The operation takes the following input parameters:
+
+* provider-type (mandatory) = 'openstack': select a specific resource provider
+  type.
+* endpoint (mandatory): target URL endpoint for the resource provider.
+* username (mandatory)
+* password (mandatory)
+* region: specified region for the provider
+* tenant
+
+  * id
+  * name
+
+
+*remove-provider*
+"""""""""""""""""
+This operation removes a resource provider from the reservation system. Note,
+this feature is not yet available in Brahmaputra release.
+
+
+
+.. [#f1] Promise requirement document,
+   http://http://artifacts.opnfv.org/promise/docs/requirements/index.html
+
+.. [#f2] YangForge framework, http://github.com/opnfv/yangforge