Use same pool_driver for different pod_vif_drivers

New config option vif_pool_mapping is added and pools_vif_drivers is
deprecated. The newer vif_pool_mapping is simply inverted mapping of
pools_vif_drivers.
Also, with the scoping ability added in cb2d308f84, independent
drv_pool instances can be acquired from base driver manager.

Earlier as a single instance of drv_pool was used by all
pod_drivers. This meant only the pod_driver which was
passed to drv_pool.set_vif_driver finally was used (for a given
drv_pool).

Please see release notes for further details.

Related-Bug: 1747406
Change-Id: Id0137f6b1a78e7aa3e3d3de639a5e989f4fd408c
Signed-off-by: Yash Gupta <y.gupta@samsung.com>

doc/source/installation/ports-pool.rst

@@ -101,10 +101,10 @@ different VIF drivers (e.g., neutron and nested-vlan).
 
 This new multi pool driver is the default pool driver used even if a different
 vif_pool_driver is set at the config option. However if the configuration
-about the mappings between the different pools and pod vif drivers is not
+about the mappings between the different pod vif and pools drivers is not
-provided at the pools_vif_drivers config option of vif_pool configuration
+provided at the vif_pool_mapping config option of vif_pool configuration
 section only one pool driver will be loaded -- using the standard
-vif_pool_driver and pod_vif_driver config options, i.e., using the one
+pod_vif_driver and vif_pool_driver  config options, i.e., using the one
 selected at kuryr.conf options.
 
 To enable the option of having different pools depending on the node's pod
@@ -114,7 +114,7 @@ driver, e.g.:
     .. code-block:: ini
 
       [vif_pool]
-      pools_vif_drivers=nested:nested-vlan,neutron:neutron-vif
+      vif_pool_mapping=nested-vlan:nested,neutron-vif:neutron
 
 This will use a pool driver nested to handle the pods whose vif driver is
 nested-vlan, and a pool driver neutron to handle the pods whose vif driver is
@@ -123,5 +123,17 @@ will first read the node's annotation about pod_vif driver to use, e.g.,
 pod_vif: nested-vlan, and then use the corresponding pool driver -- which has
 the right pod-vif driver set.
 
+.. note::
+
+  Previously, `pools_vif_drivers` configuration option provided similar
+  functionality, but is now deprecated and not recommended.
+  It stored a mapping from pool_driver => pod_vif_driver instead, disallowing
+  the use of a single pool driver as keys for multiple pod_vif_drivers.
+
+  .. code-block:: ini
+
+    [vif_pool]
+    pools_vif_drivers=nested:nested-vlan,neutron:neutron-vif
+
 Note that if no annotation is set on a node, the default pod_vif_driver is
 used.

kuryr_kubernetes/controller/drivers/vif_pool.py

@@ -26,6 +26,7 @@ from oslo_cache import core as cache
 from oslo_concurrency import lockutils
 from oslo_config import cfg as oslo_cfg
 from oslo_log import log as logging
+from oslo_log import versionutils
 from oslo_serialization import jsonutils
 
 from kuryr_kubernetes import clients
@@ -61,6 +62,17 @@ vif_pool_driver_opts = [
                             "used. If not set, it will take them from the "
                             "kubernetes driver options for pool and pod "
                             "drivers respectively"),
+                     default={}, deprecated_for_removal=True,
+                     deprecated_since="Stein",
+                     deprecated_reason=_(
+                         "Mapping from pool->vif does not allow different "
+                         "vifs to use the same pool driver. "
+                         "Use vif_pool_mapping instead.")),
+    oslo_cfg.DictOpt('vif_pool_mapping',
+                     help=_("Dict with the pod driver and the corresponding "
+                            "pool driver to be used. If not set, it will take "
+                            "them from the kubernetes driver options for pool "
+                            "and pod drivers respectively"),
                      default={}),
 ]
 
@@ -775,15 +787,16 @@ class MultiVIFPool(base.VIFPoolDriver):
 
     def set_vif_driver(self):
         self._vif_drvs = {}
-        pools_vif_drivers = oslo_cfg.CONF.vif_pool.pools_vif_drivers
+        vif_pool_mapping = self._get_vif_pool_mapping()
-        if not pools_vif_drivers:
+
+        if not vif_pool_mapping:
             pod_vif = oslo_cfg.CONF.kubernetes.pod_vif_driver
             drv_vif = base.PodVIFDriver.get_instance()
             drv_pool = base.VIFPoolDriver.get_instance()
             drv_pool.set_vif_driver(drv_vif)
             self._vif_drvs[pod_vif] = drv_pool
             return
-        for pool_driver, pod_driver in pools_vif_drivers.items():
+        for pod_driver, pool_driver in vif_pool_mapping.items():
             if not utils.check_suitable_multi_pool_driver_opt(pool_driver,
                                                               pod_driver):
                 LOG.error("The pool and pod driver selected are not "
@@ -792,7 +805,7 @@ class MultiVIFPool(base.VIFPoolDriver):
             drv_vif = base.PodVIFDriver.get_instance(
                 specific_driver=pod_driver)
             drv_pool = base.VIFPoolDriver.get_instance(
-                specific_driver=pool_driver)
+                specific_driver=pool_driver, scope='for:{}'.format(pod_driver))
             drv_pool.set_vif_driver(drv_vif)
             self._vif_drvs[pod_driver] = drv_pool
 
@@ -839,3 +852,20 @@ class MultiVIFPool(base.VIFPoolDriver):
     def _get_vif_drv_alias(self, vif):
         vif_type_name = type(vif).__name__
         return VIF_TYPE_TO_DRIVER_MAPPING[vif_type_name]
+
+    def _get_vif_pool_mapping(self):
+        vif_pool_mapping = oslo_cfg.CONF.vif_pool.vif_pool_mapping
+
+        if not vif_pool_mapping:
+            pools_vif_drivers = oslo_cfg.CONF.vif_pool.pools_vif_drivers
+
+            if pools_vif_drivers:
+                msg = ("Config option vif_pool.pools_vif_drivers is "
+                       "deprecated in favour of vif_pool.vif_pool_mapping, "
+                       "and will be removed in a future release")
+                versionutils.report_deprecated_feature(LOG, msg)
+
+            for pool_driver, pod_driver in pools_vif_drivers.items():
+                vif_pool_mapping[pod_driver] = pool_driver
+
+        return vif_pool_mapping

releasenotes/notes/reusable-pool-drivers-00e7fdc1f4738441.yaml

@@ -0,0 +1,31 @@
+---
+features:
+  - |
+    It is now possible to use same pool_driver for different pod_vif_drivers
+    when using MultiVIFPool driver.
+
+    A new config option `vif_pool.vif_pool_mapping` is introduced which is a
+    dict/mapping from pod_vif_driver => pool_driver. So different
+    pod_vif_drivers can be configured to use the same pool_driver.
+
+    .. code-block:: ini
+
+      [vif_pool]
+      vif_pool_mapping=nested-vlan:nested,neutron-vif:neutron
+
+    Earlier each instance of a pool_driver was mapped to a single
+    pod_driver, thus requiring a unique pool_driver for each pod_vif_driver.
+upgrade:
+  - |
+    If ``vif_pool.pools_vif_drivers`` config option is used, new config option
+    `vif_pool.vif_pool_mapping` should be populated with inverted mapping
+    from the present value of ``vif_pool.pools_vif_drivers``.
+deprecations:
+  - |
+    Configuration option ``vif_pool.pools_vif_drivers`` has been deprecated in
+    favour of ``vif_pool.vif_pool_mapping`` to allow reuse of pool_drivers for
+    different pod_vif_drivers.
+
+    If ``vif_pool_mapping`` is not configured, ``pools_vif_drivers`` will still
+    continue to work for now, but ``pools_vif_drivers`` will be completely
+    removed in a future release.