Add ALL-IN operator to extra spec ops

Allow extra spec to match all values in a list by adding the ALL-IN
operator.

blueprint add-all-in-list-operator-to-extra-spec-ops
Previously-approved: juno

Change-Id: Ie3b6fe789118e170f03f87588e4d310bb6da604d

specs/kilo/approved/add-all-in-list-operator-to-extra-spec-ops.rst

@@ -0,0 +1,167 @@
+..
+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+======================================
+Add ALL-IN operator to extra spec ops
+======================================
+
+`https://blueprints.launchpad.net/nova/+spec/add-all-in-list-
+operator-to-extra-spec-ops
+<https://blueprints.launchpad.net/nova/+spec/add-all-in-list-
+operator-to-extra-spec-ops>`_
+
+Allow extra spec to match all values in a list by adding the ALL-IN operator.
+
+
+Problem description
+===================
+
+This blueprint aims to allow querying if ALL of the given values are present
+in a list.
+
+Currently there's support for an IN operator that returns True if a given
+element is present in a list. There is also an OR operator that
+only works for single values.
+
+Use Cases
+---------
+
+Suppose operator or user want a flavor that will place VMs on a host that has
+the cpu flags 'aes' and 'vmx'. As it is today is not possible since the only
+posibility is to use the <in> operator. But, as the extra specs is a dict, the
+flavor extra-spec key would be the same:
+
+capabilities:cpu_info:features : <in> aes
+capabilities:cpu_info:features : <in> vmx
+
+Just one of them will be saved.
+
+Something like this is needed:
+
+capabilities:cpu_info:features : <all-in> aes vmx
+
+Project Priority
+----------------
+This blueprint doest't fit into scheduler priorities for Kilo. It was accepted
+for Juno.
+
+Proposed change
+===============
+
+We need to add the new <all-in> operator and its lambda function to
+_op_methods dict in extra_specs_ops.py.
+
+...
+'<all-in>': lambda x, y: all(val in x for val in y),
+...
+
+Then add a call to this function with a list, instead of with a
+string if there are more than one element in the query.
+
+
+Alternatives
+------------
+
+Instead of add the '<all-in>' operator extend/overload the '<in>' operator to
+work with a list.
+
+capabilities:cpu_info:features : <in> aes vmx
+
+Seems to be easy to understand but could generate confusion because <in>
+operator as it is today, aims to be used to match a substring.
+
+Another possibility is add both <any> and <all> operators. By doing this, we
+are using <in> and <or> for single values and the new set of operators for
+collections values. But something is missing with this approach,
+<all> or <any> what? All elements in a list, all elements are True, or all
+elements are equal to a given value.
+
+
+Data model impact
+-----------------
+
+None
+
+REST API impact
+---------------
+
+None
+
+Security impact
+---------------
+
+None
+
+Notifications impact
+--------------------
+
+None
+
+Other end user impact
+---------------------
+
+None
+
+Performance Impact
+------------------
+
+None
+
+Other deployer impact
+---------------------
+
+None
+
+Developer impact
+----------------
+
+None
+
+Implementation
+==============
+
+Add a new lamda function to
+nova/scheduler/filter/extra_specs_ops.py _ops_method dict:
+
+'<all-in>': lambda x, y: all(val in x for val in y)
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  artur-malinowski
+
+Other contributors:
+  pawel-koniszewski
+  facundo-n-maldonado
+
+Work Items
+----------
+
+The change is simple and can be done in one Gerrit patch. Implementation is
+acutally completed.
+
+Dependencies
+============
+
+None
+
+Testing
+=======
+
+Unit tests should be added for the new operator.
+
+Documentation Impact
+====================
+
+Filter scheduler documentation should be updated with the new operator.
+
+References
+==========
+
+* Approved spec for Juno: https://review.openstack.org/#/c/98179/
+* Implementation: https://review.openstack.org/#/c/102631/
+