watcher-specs/specs/newton/implemented/optimization-threshold.rst

Optimization Threshold

https://blueprints.launchpad.net/watcher/+spec/optimization-threshold

Allow decision engine to pass strategy parameters, like optimization threshold, to selected strategy, also strategy to provide parameters info to end user.

Problem description

Currently all parameters used in strategy are hard coded, end users can't modify them unless they change the source code. E.g. THRESHOLD of strategy outlet_temp_control is critical and fixed as 35.0, so we can't tune it for specific usage case without changing source code.

Use Cases

As an administrator. I can choose a goal to optimize my cluster and Watcher will show me a list of custom parameters for the selected strategy.

As an operator. I want to tune the strategy parameter in an easy way for my cloud. I wish I can change it via watcher command line to achieve the best solution.

Project Priority

Not relevant because Watcher is not in the big tent so far.

Proposed change

Need following to enable strategy parameter:

• Add more info into audit-template, so that 'watcher audit-template-show' tells end user selected strategy and its parameters. Also append these info to the 'watcher audit-template-create' output.
• Add new cmd option '-p' to 'watcher audit-create' for strategy parameter configuration. End user can specify all strategy parameters, like "-p threshold=45.0 -p repeat=10".
• When 'watcher audit-create', decison engine would configure selected strategy with these parameters before executing it.

Alternatives

None

Data model impact

For audit template, need add info of selected strategy and its parameters. For audit, need store user specified strategy parameters by hashmap.

The audit template structure is as follows:

+----------------+-------------------------------------------+
| Property       | Value                                     |
+----------------+-------------------------------------------+
| goal           | DUMMY                                     |
| strategy       | outlet_temp_control                       |
| parameter_info | {'threshold': (float, 'Temperature ...')} |
| description    | None                                      |
| name           | 1th_template                              |
| host_aggregate | None                                      |
| uuid           | 0c49a52c-4a0f-4dea-9e19-471360823aef      |
+----------------+-------------------------------------------+

The audit structure is as follows:

+---------------------+--------------------------------------+
| Property            | Value                                |
+---------------------+--------------------------------------+
| uuid                | b564665b-e77b-444c-a43f-3ae654b9a551 |
| audit_template_name | 1st_template                         |
| parameters          | {'threshold': 35.0}                  |
| created_at          | 2016-01-31T08:51:03+00:00            |
| updated_at          | 2016-01-31T08:51:58+00:00            |
| audit_template_uuid | 06cdba2a-069b-4618-8948-540854d8d911 |
| state               | SUCCEEDED                            |
| deadline            | None                                 |
| deleted_at          | None                                 |
| type                | ONESHOT                              |
+---------------------+--------------------------------------+

REST API impact

Audit creation API: POST /v1/audit is changed, so that extra strategy parameters hashmap is accepted in request body.

E.g. to create one audit based on outlet_temperature template with required parameters, we can just POST following:

{
    "type": "ONESHOT",
    "audit_template_uuid": "outlet_temperature_template",
    "parameters": {
        "threshold": 35.0,
        "repeat": 10
    }
}

Security impact

Strategy parameter controls the executing process, and odd parameter probably leads unexpected behavior. This BP enables easy changing of parameter, thus need check against input parameter to make sure it is in reasonable range.

Notifications impact

None

Other end user impact

python-watcherclient need add extra command line for parameter input. End user needs to be aware of this for strategy parameter tuning.

Performance Impact

None

Other deployer impact

None

Developer impact

None

Implementation

Assignee(s)

Primary assignee:

edwin-zhai

Work Items

• Refactor the code to move strategy selection from audit creation to audit-template creation. As we have no strategy parameter info until instantiate it.
• Extend the audit-template to show the info of selected strategy and related parameters
• Add extra command line in python-watcherclient, so that strategy parameter can be specified with 'watcher audit-create -p xxx=XXX -p yyy=YYY ...'
• When 'watcher audit-create', parameter should be used to configure the selected strategy after validation, where voluptuous can be used just like action parameter checking.
• Update Horizon plugin for watcher to make sure it still works with these changes.
• Each strategy class with parameter need define a new function, 'input_parameters', to set all parameters, e.g. threshold.
• Each strategy calss with parameter need define a new function, 'parameters_info', to return parameter info, like 'name', 'type' and 'description'.

Dependencies

None

Testing

Adds unit and functional test for strategy parameter.

Documentation Impact

Need update the watcher API doc and user guide. In dev doc about strategy implementation, need explain how to add input parameters for strategy.

References

None

History

None