need to set metadata_workers when using local metadata service

[Edward Hope-Morley]

We are currently not setting metadata_workers when local metadata service on nova-compute hosts which results in automatically generated values based on number of cpus in the host. This results in more workers than required for systems with large numbers of cpus so we should make this configurable like the worker settings in the api charms.

[Hua Zhang (zhhuabj)]

Paste this link [1] for your reference, it proposes to use the following formula:

- for controllers: min(max($::processorcount, 2), $workers_max)
- for computes (DVR): min($::processorcount / 8 + 1, $workers_max))

[1] https://bugs.launchpad.net/mos/+bug/1575724

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/493090

[Edward Hope-Morley (hopem)]

I inadvertently removed the nova-compute target when this bug does actually require both neutron-openvswitch and nova=compute to support configuring the number of workers used for the metadata api/agent.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/493487

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/493090
Committed: https://git.openstack.org/cgit/openstack/charm-neutron-openvswitch/commit/?id=fbed3f3d7a9c2a0804c7c0ae862779b2144af8f4
Submitter: Jenkins
Branch: master

commit fbed3f3d7a9c2a0804c7c0ae862779b2144af8f4
Author: Edward Hope-Morley <email address hidden>
Date: Fri Aug 11 18:20:13 2017 +0100

    Support configurable metadata_workers

    Adds config option worker-multiplier to allow
    configuring the number of workers used for the
    metadata api when using local dhcp.

    Change-Id: Ie3a7d6aab0d9902a6637637fbf75b2df3ec084b1
    Closes-Bug: 1707618

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/493487
Committed: https://git.openstack.org/cgit/openstack/charm-nova-compute/commit/?id=7a45db6274eb37dfca69c14148dbcca135a9be4b
Submitter: Jenkins
Branch: master

commit 7a45db6274eb37dfca69c14148dbcca135a9be4b
Author: Edward Hope-Morley <email address hidden>
Date: Mon Aug 14 10:09:03 2017 +0100

    Support configurable metadata_workers

    Adds config option worker-multiplier to allow configuring
    the number of workers used for the metadata api when
    using local dhcp or dvr.

    Change-Id: I505963165f8a4fade0123c2825af00189285f168
    Closes-Bug: 1707618