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Re: Hadoop Provider Integration

 

Team,

I've created the mockups for UI dialogs responsible for launching cluster
and creating node template:

https://wiki.openstack.org/wiki/File:Savanna-create-cluster-mockup.png

https://wiki.openstack.org/wiki/File:Savanna-node-template-mockup.png
I think they should help understand our view in the whole, and clarify our
Plugin API design reasoning. IMHO, the create cluster dialog maps pretty
nicely to cluster_description object from the Plugin API. The main thing
which is different in the API is that Node Templates are replaced with
configs.

Initially we introduced Node Templates to let user specify some parameters
only once during template creation. When user creates a cluster, he don't
need to specify each parameter, he just needs to select one of the
templates. To simplify Node Templates usage and management, we want to
organize them in hierarchical structure, so that a template can extend
another template. This approach will let user specify most parameters in
base template, and override only few of them in each descending template.

As you can see from the second mockup, a template in nutshell is just a
list of key-value pairs.

We don't want to burden plugin with processing Templates, deciding who
inherits who, etc. We want Savanna to handle this and provide plugin only
the resulting list of configs (key-value pairs), hence such transition from
UI to API.

Hope that clarifies,

Dmitry



2013/5/2 Dmitry Mescheryakov <dmescheryakov@xxxxxxxxxxxx>

> Erik, team,
>
> We've composed a document which more precisely describes our vision of
> Plugin API:
>
> https://wiki.openstack.org/w/images/1/19/Savanna-plugin-api.pdf
>
> The document mostly focuses on describing functions we've already
> introduced. And it almost does not incorporate your input yet, this is work
> to be done.
>
> Thanks,
>
> Dmitry
>
>
>
>
> 2013/5/1 Dmitry Mescheryakov <dmescheryakov@xxxxxxxxxxxx>
>
>> *
>>
>> Hey Erik, team,
>>
>> Thank you for deeper dive into plugin mechanism architecture. That is
>> really a step forward.
>>
>> Let us discuss the general approach first. When we started the
>> architecture design, we also first thought of an IoC concept, similar to
>> what you suggest. But after some thinking, we found that it is better to
>> split one big “create cluster” call into a number of smaller ones,
>> retaining more control on the core side. The benefits of such approach (and
>> disadvantages of the opposite one) are:
>>
>> * In case of one “create cluster” call each plugin will be allowed to
>> have different behavior, which means we will introduce a lot of undefined
>> behavior. Especially in error cases, because each plugin could handle error
>> case differently. Another thing is that handling such cases might require
>> deep knowledge of OpenStack from plugin creator. Our goal is to simplify
>> plugin creation process by handling all the OpenStack related logic inside
>> the Savanna code, not in the plugin code.
>>
>> In case of separate calls for each step:
>>
>> * Plugin is separated into several consecutive parts/methods. Transitions
>> between these methods might be persisted which would increase reliability
>> of the workflow.
>>
>> In perspective, it might allow to run plugin in distributed environment.
>>
>> * Separate and defined by API plugin methods allow code reuse. It also
>> serves as a documentation of plugins responsibilities.
>>
>> * It’ll allow timeout handling for each step on the core side.
>>
>>
>> Methods for interacting directly with a VM/Server instance like
>> install(), open_file(), interactive execute() don’t seem to be relevant to
>> the Plugin API. It’s better to keep such method away from the API to keep
>> that API as simple as possible. It can be just a set of helper methods
>> under utils package.
>>
>> We suggest to move provider specific details to separate blueprints.
>> Examples are “HDP specific details” in create cluster flow and in add hosts
>> flow.
>>
>> Thanks,
>>
>> Dmitry, on behalf of Mirantis team
>>
>> *
>>
>>
>> 2013/4/30 Erik Bergenholtz <ebergenholtz@xxxxxxxxxxxxxxx>
>>
>>> Dmitry - uploaded a new doc that looks a bit better:
>>> https://wiki.openstack.org/w/images/5/5e/Savanna_Deployment_Engine_Architecture.pdf
>>>
>>> Erik
>>>
>>> On Apr 30, 2013, at 4:20 PM, Dmitry Mescheryakov <
>>> dmescheryakov@xxxxxxxxxxxx> wrote:
>>>
>>> Hey Erik,
>>>
>>> Some tables in "Savanna Deployment Engine Architecture" doc are
>>> flattened out, see attached screenshot for example. Could you reassemble
>>> the PDF with correct tables' sizes?
>>>
>>> Thanks,
>>>
>>> Dmitry
>>>
>>>
>>> 2013/4/30 Erik Bergenholtz <ebergenholtz@xxxxxxxxxxxxxxx>
>>>
>>>> Team - yet another update. See
>>>> https://wiki.openstack.org/w/images/9/97/Savanna_hadoop_host_group_mapping.pdf for
>>>> a document illustrating how hadoop nodes get mapped to provisioned VMs.
>>>> Erik
>>>>
>>>>
>>>>
>>>> On Apr 30, 2013, at 11:07 AM, Erik Bergenholtz <
>>>> ebergenholtz@xxxxxxxxxxxxxxx> wrote:
>>>>
>>>> Team,  John has updated the below referenced documents with better
>>>> descriptions of the flows (same links apply).
>>>>
>>>> Cheers,
>>>>
>>>> Erik
>>>>
>>>> On Apr 30, 2013, at 6:35 AM, Erik Bergenholtz <
>>>> ebergenholtz@xxxxxxxxxxxxxxx> wrote:
>>>>
>>>> Team,
>>>>
>>>> Below are a few documents intended to describe only a slightly modified
>>>> approach to hadoop provider integration into Savanna (see existing
>>>> blueprint in draft:
>>>> https://blueprints.launchpad.net/savanna/+spec/pluggable-cluster-provisioning). These
>>>> documents should not be considered a blueprint, but a vehicle for
>>>> continuing discussion on the topic.
>>>>
>>>> To summarize there are two changes to note:
>>>>
>>>> 1. There is some IoC introduced into the design allowing hadoop plugin
>>>> providers flexibility to integrate into Savanna while reducing the burden
>>>> on the Savanna controller itself. This differs from the current approach of
>>>> the controller invoking APIs on the provider at specific lifecycle points.
>>>>
>>>> 2. Attempts have been made to keep normalization of management APIs
>>>> across providers at a minimum at the controller level. Our view is that
>>>> existing Hadoop users are already familiar with their Hadoop distribution
>>>> management API (CDH, Ambari, MapR etc.) and as such would want to leverage
>>>> existing investments vs. learning a new management API specific to Savanna.
>>>> This eases adoption and lowers the barrier of entry of adoption of Hadoop
>>>> on OpenStack.
>>>>
>>>> Documents to review:
>>>>
>>>> Savanna Deployment Engine Architecture<https://wiki.openstack.org/w/images/5/5e/Savanna_Deployment_Engine_Architecture.pdf> -
>>>> Puts forth the architecture of the deployment engine
>>>> Savanna_add_hosts_flow<https://wiki.openstack.org/w/images/d/dc/Savanna_add_hosts_flow.pdf> -
>>>> Describes sequence of steps executed in order to add a host to an existing
>>>> Hadoop Cluster
>>>> Savanna_create_cluster_flow<https://wiki.openstack.org/w/images/0/0f/Savanna_create_cluster_flow.pdf> -
>>>> Describes the sequence of steps executed in order to create a new cluster
>>>> Savanna_invoke_provider_rest_api_flow<https://wiki.openstack.org/w/images/a/a6/Savanna_invoke_provider_rest_api_flow.pdf> -
>>>> Describes the sequence of steps executed in a REST request by the provider
>>>> plugin on the controller.
>>>>
>>>> Please review at your earliest convenience and let us know your
>>>> feedback.
>>>>
>>>> Best,
>>>>
>>>> Jon Maron, John Speidel and Erik Bergenholtz
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> --
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>>>>
>>>>
>>> <Screen Shot 2013-04-30 at 1.15.11 PM.png>
>>>
>>>
>>>
>>
>

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