Code review comment for lp:~axwalk/juju-core/provider-unit-assignment-policy

Reviewers: mp+221481_code.launchpad.net,

Message:
Please take a look.

Description:
Introduce InstanceDistributor policy

This change introduces an InstanceDistributor
policy, which will be used to implement automatic
Availability Zone management for AWS and OpenStack.

When an attempt is made to assign a unit to a clean
machine, we gather the instances that have already
been provisioned, and provide those and the unit's
distribution group to the provider. The provider
may select as many or as few of the candidates as it
wishes to allow; the assignment policy will then
choose one of them for assigning to. If no candidates
are returned, the unit will be assigned to a new
machine.

There are currently no implementations of this policy;
they will be forthcoming when manual AZ support lands
in the amazon/openstack providers.

https://code.launchpad.net/~axwalk/juju-core/provider-unit-assignment-policy/+merge/221481

(do not edit description out of merge proposal)

Please review this at https://codereview.appspot.com/99660047/

Affected files (+379, -40 lines):
   A [revision details]
   M environs/statepolicy.go
   M state/apiserver/provisioner/provisioner.go
   M state/conn_test.go
   A state/distribution.go
   A state/distribution_test.go
   M state/policy.go
   M state/unit.go