monasca-statsd is a non-optional import even when disabled

[David Moreau Simard]

https://review.openstack.org/#/c/322252/ introduced a monasca-statsd metrics implementation which claims to be disabled by default: https://review.openstack.org/#/c/322252/18/etc/designate/designate.conf.sample

But the import is non-optional and will cause stack traces if monasca-statsd is not installed:
http://logs.openstack.org/51/382351/3/check/gate-puppet-openstack-integration-4-scenario003-tempest-centos-7/ea19afd/logs/syslog.txt.gz#_Oct_05_15_40_12

This should be considered an optional metrics backend, such as there are different backends in Cinder or Glance. It should not be in requirements.txt but be a requirement when the monasca metrics are enabled.

If someone is not interested in the Monasca metrics, he should not need to install it for designate to work.

[Tim Simmons (timsim)]

We should probably be using setup.cfg optional requirement groups for this, we'll talk to the infra folks, because that's currently not a thing that is supported.

[Tim Simmons (timsim)]

In the meantime, we should endeavor to make this not a required import.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/389800

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/389800
Committed: https://git.openstack.org/cgit/openstack/designate/commit/?id=417efcc510ef476e550c03ef6d33899bf5b5ca99
Submitter: Jenkins
Branch: master

commit 417efcc510ef476e550c03ef6d33899bf5b5ca99
Author: Alex Schultz <email address hidden>
Date: Fri Oct 21 11:06:27 2016 -0600

    Add noop metrics client

    With the addition of monasca-statsd as part of
    I990472fa059afde37f7e4a1284360c17162aab49, it's a required dependency
    even if not used. For upstream packages which do not have the
    monasca-statsd available, we need to be able to continue to have
    designate working without it. This change makes the monasca-statsd
    dependency optional at runtime by falling back to a noop client that
    mocks out the interface for monasca-statsd but does nothing.

    Change-Id: Idf986c514b26f1d2799903b2a4e581a1166343cc
    Closes-Bug: #1630666

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/designate 4.0.0.0b2 development milestone.