Open Stack

Some services/components are related or have dependencies on other 
services and components.As an example, in HDP, the Hive service depends 
on HBase and Zookeeper.In Savanna, there is no way to express this 
relationship.If a user wanted to deploy Hive, they would need to know to 
install both HBase and Zookeeper a priori.Also, because the list of 
service components(node processes) that is provided to a user to be used 
in node groups is a flat list, only the component name gives any 
indication as to what service the components belong to.Because of this, 
it will likely be difficult for the user to understand exactly what 
components are required to be installed for a given 
service(s).Currently, the HDP stack consists of approximately 25 service 
components.


A primary reason that it isn't currently possible to express 
service/component relationships is that topology is defined from the 
bottom up.This means that a user first selects components and assigns 
them to a node template.The users first interaction is with components, 
not services.Currently, the user will not know if a given topology is 
valid until an attempt is made to deploy a cluster and validate is 
called on the plugin.At this point, if the topology were invalid, the 
user would need to go back and create new node and cluster templates.



One way to express service relationships would be to define topology top 
down, with the user first selecting services.After selecting services, 
the related service components could be listed and the required 
components could be noted. This approach is a significant change to how 
Savanna currently works, has not been thoroughly thought through and and 
is only meant to promote conversation on the matter.



After making new services available from the HDP plugin, it is clear 
that defining a desired (valid) topology will be very difficult and 
error prone with the current savanna architecture.I look forward to 
discussing solutions to this matter with the community.


-John

-- 
CONFIDENTIALITY NOTICE
NOTICE: This message is intended for the use of the individual or entity to 
which it is addressed and may contain information that is confidential, 
privileged and exempt from disclosure under applicable law. If the reader 
of this message is not the intended recipient, you are hereby notified that 
any printing, copying, dissemination, distribution, disclosure or 
forwarding of this communication is strictly prohibited. If you have 
received this communication in error, please contact the sender immediately 
and delete it from your system. Thank You.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstack.org/pipermail/openstack-dev/attachments/20130827/c77aabe5/attachment.html>