[openstack-dev] [Fuel][Solar] SolarDB/ConfigDB place in Fuel

Dmitriy Shulyak dshulyak at mirantis.com
Tue Dec 15 23:03:57 UTC 2015


Hello folks,

This topic is about configuration storage which will connect data sources
(nailgun/bareon/others) and orchestration. And right now we are developing
two projects that will overlap a bit.

I understand there is not enough context to dive into this thread right
away, but i will appreciate if those people, who participated in design,
will add their opinions/clarifications on this matter.

Main disagreements
---------------------------
1. configdb should be passive, writing to configdb is someone else
responsibility
+ simpler implementation, easier to use
- we will need another component that will do writing, or split this
responsibility somehow

2. can be used without other solar components
+ clear inteface between solar components and storage layer
- additional work required to design/refactor communication layer between
modules in solar
- some data will be duplicated between solar orchestrator layer and configdb

3. templates for output
technical detail, can be added on top of solardb if required

Similar functionality
--------------------------
1. Hierachical storage
2. Versioning of changes
3. Possibility to overwrite config values
4. Schema for inputs

Overall it seems that we share same goals for both services,
the difference lies in organizational and technical implementation details.

Possible solutions
------------------------
1. develop configdb and solar with duplicated functionality
- at least 2 additional components will be added to the picture,
one is configdb, another one will need to sync data between configdb and
solar
- in some cases data in solar and configdb will be 100% duplicated
- different teams will work on same functionality
- integration of additional component for fuel will require integration with
configdb and with solar
+ configdb will be independent from solar orchestration/other components

2. make service out of solardb, allign with configdb use cases
+ solardb will be independent from solar orchestration/other solar
components
+ integration of fuel component will be easier than in 1st version
+ clarity about components responsibility and new architecture
- redesign/refactoring communication between components in solar

3. do not use configdb/no extraction of solardb
- inproc communication, which can lead to coupled components (not the case
currently)
+ faster implementation (no major changes required for integration with
fuel)
+ clarity about components responsibility and new architecture

Summary
-------------
For solar it makes no difference where data will come from: configdb or
data sources, but in overall fuel architecture it will lead to significant
complexity increase.
It would be the best to follow 2nd path, because in long term we don't want
tightly coupled components, but in nearest future we need to concentrate
on:
- integration with fuel
- implementing policy engine
- polishing solar components
This is why i am not sure that we can spend time on 2nd path right now,
or even before 9.0.
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