Function Aliases spec proposal

Change-Id: I4f3a08567873ab54762504816a69797ee77ec22c
Story: #2001588
task: #6537

doc/source/specs/function_aliases.rst

@@ -0,0 +1,145 @@
+..
+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+================================
+Support Qinling function aliases
+================================
+
+https://storyboard.openstack.org/#!/story/2001588
+
+Function aliases are like pointers to the specific funtion versions. By using
+aliases, you can access the specific version of a function an alias is pointing
+to (for example, to invoke the function) without having to know the specific
+version the alias is pointing to. Function aliases enable the following use
+cases:
+
+- Easier support for promotion of new versions of functions and rollback when
+  needed.
+
+- Simplify management of event source mappings.
+
+
+Problem description
+===================
+
+- As a function developer, you want to create an alias that points to function
+  version, and remapping of aliases to different function versions.
+
+- As an application developer who relies on the Qinling functions, I want a
+  safe and sustainable way to call the functions without changing the
+  applications after the function is updated.
+
+
+Proposed change
+===============
+
+Data model impact
+-----------------
+
+A new database table needs to be created to store the mappings from alias to
+function and function version.
+
+REST API impact
+---------------
+
+* Create function alias that points to the specified function version. After
+  creation, Qinling returns the function alias information, including
+  function id, version id, alias name, description
+  and timestamps.
+
+  * POST ``/aliases``
+  * Parameters: function_id
+  * Parameters: description
+  * Parameters: function_version
+  * Parameters: name
+
+    * the 'name' must be unique within the project
+
+* Update function alias. Update the function id and version to which the alias
+  points and alias description.
+
+  * PUT ``/aliases/<alias_name>``
+  * Parameters: function_id
+  * Parameters: description
+  * Parameters: function version
+
+* Get the specified function alias information.
+
+  * GET ``/aliases/<alias_name>``
+
+* List the aliases.
+
+  * GET ``/aliases/``
+
+* Delete specific function alias. When deleting alias, need to check if there is
+  any webhook/running job using the alias.
+
+  * DELETE ``/aliases/<alias_name>``
+
+* Create execution. Create execution with alias, so the execution will be
+  created with the function id and version number the alias points to.
+
+* Create job. Create job with alias, so the job will be created with the
+  function id and version number the alias points to.
+
+* Create webhook. Create webhook with alias, so the webhook will be
+  created with the function id and version number the alias points to.
+
+* Delete function. Qinling needs to check if there is any alias using that
+  function, if there is alias associated with the function, the function
+  deletion will fail.
+
+* Delete function version. Qinling needs to check if there is any alias using that
+  function version, if there is alias associated with the function version,
+  the function version deleteion will fail.
+
+End user impact
+---------------
+
+All the API changes should be supported in CLI.
+
+Performance Impact
+------------------
+
+None
+
+Deployer impact
+---------------
+
+Database migration script is provided.
+
+Alternatives
+------------
+
+None
+
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Dong Ma <winterma.dong@gmail.com>
+
+
+Dependencies
+============
+
+None
+
+
+Testing
+=======
+
+Pay attention to the notes written in ``REST API impact`` section.
+
+
+References
+==========
+
+* Introduction to AWS Lambda Aliases
+  https://docs.aws.amazon.com/lambda/latest/dg/aliases-intro.html

doc/source/specs/index.rst

@@ -30,6 +30,7 @@ Specs
 
     function_versioning
     customize_resource
+    function_aliases
 
 Template
 --------