driver/openstack: order flavor results

I hit a situation in a new cloud where I had defined two flavors with
the same amount of RAM "opendev-control" and "opendev".  The config
had min-ram set [1] with a flavor-name of "opendev" -- I expected it
to match the exact name first, but nodepool was choosing
"opendev-control".

I guess the default order returned by the cloud is flavorid [2].  I'd
propose that sorting on a tuple of (ram, name) -- so that we match
names in alphabetical order -- is a more intuitive way to run the
match.

Documentation is updated, and a release note added.

[1] which actually we didn't want, really, because we wanted to
    exactly match the flavor:
     https://review.opendev.org/c/openstack/project-config/+/870677
[2] https://docs.openstack.org/api-ref/compute/?expanded=list-flavors-detail#list-flavors

Change-Id: I268dd598ca9f1b617c5062b41ad27d0305df60b9

doc/source/openstack.rst

@@ -575,11 +575,16 @@ Selecting the OpenStack driver adds the following options to the
 
            Name or id of the flavor to use. If
            :attr:`providers.[openstack].pools.labels.min-ram` is
-           omitted, it must be an exact match. If
-           :attr:`providers.[openstack].pools.labels.min-ram` is given,
-           ``flavor-name`` will be used to find flavor names that meet
+           omitted, it must be an exact match.
+
+           If :attr:`providers.[openstack].pools.labels.min-ram` is
+           given, ``flavor-name`` will be used to find flavor names
+           that meet
            :attr:`providers.[openstack].pools.labels.min-ram` and also
-           contain ``flavor-name``.
+           contain ``flavor-name``.  Flavors that match the RAM
+           requirements will be examined in standard alphabetical
+           order; the first to contain the ``flavor-name`` string will
+           be chosen.
 
            One of :attr:`providers.[openstack].pools.labels.min-ram` or
            :attr:`providers.[openstack].pools.labels.flavor-name` must

nodepool/driver/openstack/adapter.py

@@ -589,7 +589,7 @@ class OpenStackAdapter(statemachine.Adapter):
 
     def _getFlavors(self):
         flavors = self._listFlavors()
-        flavors.sort(key=operator.itemgetter('ram'))
+        flavors.sort(key=operator.itemgetter('ram', 'name'))
         return flavors
 
     def _findFlavorByName(self, flavor_name):

releasenotes/notes/flavors-alphabetical-fdf2196d64e7eb00.yaml

@@ -0,0 +1,10 @@
+---
+upgrade:
+  - |
+    In the OpenStack driver, when using ```min-ram``` in combination
+    with a ```flavor-name```, the first flavor to be found that
+    satisfied the ```min-ram``` requirements and contained the
+    substring ``flavor-name``` would be used.  The order of the
+    flavors to be searched was dependent on what the cloud returned.
+    From this release, the available flavors are now alphabetically
+    sorted before matching ```flavor-name```.