a6466059bb
As suggested, created a new patch to correct some nits in previous spec patch, don't want to block the main one due to small things. Change-Id: I69df2f1003fd109880be30010bf0b465dece0ca6
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This work is licensed under a Creative Commons Attribution 3.0 Unported
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License.
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http://creativecommons.org/licenses/by/3.0/legalcode
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========================================================================
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Adding new nova-manage cmd to list compute node metrics
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========================================================================
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https://blueprints.launchpad.net/nova/+spec/compute-node-metrics-list
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We need a way to list the available metrics stored in the DB
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which is reported by the compute monitor plugins, so the administrator
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can easily configure the scheduler's MetricWeigher settings.
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Problem description
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===================
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With the Icehouse blueprint implementation
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https://blueprints.launchpad.net/nova/+spec/utilization-aware-scheduling,
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now various monitor plug-ins can be configured to report hypervisor
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metrics periodically. These metrics could be used in scheduling process
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through the MetricsWeigher configured by the administrator.
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When the administrator wants to configure the settings for MetricsWeigher,
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he/she need to know the exact metrics to make the settings working
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properly. Currently, we don't have a way to let the administrator know what
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metrics are available unless asking the administrator to look at the monitor
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plug-ins code or looking in certain DB tables.
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We need a way to list the available metrics currently reported
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by the nova compute monitors and stored in the DB, so the administrator
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can configure the MetricWeigher much more easily.
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Use Cases
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----------
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The Administrator will use this way to list all the available metric names,
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in order to configure the MetricsWeigher to work as expected.
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Proposed change
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===============
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A new nova-manage command will be added::
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nova-manage host_metric [--host=<host>] { list | show }
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This command will load the information from nova DB about all the available
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compute node metrics stored there. The 'list' action will list all the
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available compute node metrics name, and the 'show' action will show all
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the details of each metric.
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Alternatives
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------------
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One alternative is to add a new method in
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nova.compute.monitors.base.MonitorBase class that would return a list of
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the metric names that each plugin supports.
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A new top-level REST API resource will be added, it simply lists the metric
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names which are returned by the new method mentioned above::
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GET /v2.1/host-metrics
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A array 'metrics' will be returned in the response of this API, listing
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all the metrics names. The response will looks like::
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200 OK
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{
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"host_metrics": [
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'cpu.kernel.time',
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'cpu.user.time',
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......
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]
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}
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This new API by default is admin only.
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Another alternative is to extend the current os-hypervisors API extension which
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list all the information about the compute node hypervisor. It pulls the
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information from the DB, but it ignores the metrics related information.
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We need to modified the os-hypervisors API extension to list the metrics
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of each compute node hypervisor through the following restful API call::
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GET /v2.1/os-hypervisors/{hypervisor_id}/metrics
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The above API would query the DB and return the metrics stored in the DB
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for the specified compute node hypervisor.
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Data model impact
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-----------------
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None
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REST API impact
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---------------
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None
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Security impact
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---------------
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None
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Notifications impact
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--------------------
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None
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Other end user impact
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---------------------
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None
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Performance Impact
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------------------
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None
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Other deployer impact
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---------------------
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None
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Developer impact
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----------------
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None
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Implementation
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==============
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Assignee(s)
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-----------
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Primary assignee:
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lianhao-lu
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Other contributors:
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None
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Work Items
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----------
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* add new nova-manage command
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Dependencies
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============
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https://review.openstack.org/#/q/project:openstack/nova+branch:master+topic:bug/1468012,n,z
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Testing
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=======
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New unit test cases will be added.
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Documentation Impact
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====================
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The admin configuration documentation need to be updated.
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References
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==========
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None
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