CC should refresh instances_retrievable services upon service update

[gberche-orange]

Issue

As a developer, in order to have CF refresh its view of a service instance which has been modified out of bands (e.g. using dashboard), I need CF to refresh the service instance following a cf update-service command

Context

Some services instances might be modified out of bands, i.e. modifications are not triggered through the current CF instance. Example related use-cases:

• the service instance was modified through a dashboard
• the service instance is shared among multiple CF deployments, and was modified by another CF deployments
• the service instance is shared among multiple OSB clients (e.g. a K8S osb client), and was modified by another CF deployments

While service brokers can express that the service instances is retrievable by publishing instances_retrievable=true in their catalog, the CC only currently uses this information to fetch service instance parameters using the GET /v2/service_instances/:instance_id broker endpoint, and ignores any updates made to the the service plan Id which remains cached.

Steps to Reproduce

• Deploy a service broker which supports out of bands service plan updates (possibly CATS service_broker or overview-broker)
• cf create-service service-offering plan1 myservice
• update out of band the service instance from plan1 to plan2
• cf update-service myservice

Expected result

cf service myservice and cf services show the service "myservice" with plan2

Current result

cf service myservice and cf services show the service "myservice" with plan1

Possible Fix

When instances_retrievable=true, a cf update-service should systematically trigger call to GET /v2/service_instances/:instance_id broker endpoint, to refresh the service plan, in addition to the dashboard url (as reported in #1390)

Additional details

Related code serving the cached service plan

cloud_controller_ng/app/controllers/services/service_instances_controller.rb

Lines 153 to 156 in 8b7d8ee

	def read(guid)
	service_instance = find_guid_and_validate_access(:read, guid, ServiceInstance)
	object_renderer.render_json(self.class, service_instance, @opts)
	end

Related code using the fetch endpoint to serve refreshed service params

cloud_controller_ng/app/controllers/services/service_instances_controller.rb

Lines 268 to 273 in 8b7d8ee

	fetcher = ServiceInstanceRead.new
	begin
	parameters = fetcher.fetch_parameters(service_instance)
	[HTTP::OK, parameters.to_json]

cloud_controller_ng/spec/unit/actions/services/service_instance_read_spec.rb

Lines 19 to 24 in 65a75e6

	it 'calls the broker to fetch parameters' do
	expect(fake_broker_client).to receive(:fetch_service_instance).with(service_instance).and_return({})
	action = ServiceInstanceRead.new
	action.fetch_parameters(service_instance)
	end

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/170012081

The labels on this github issue will be updated when the story is started.

[gberche-orange]

@addytripathi this relates to #1390 and would be worth taking into account for service instance v3. I suggested related pain entry in https://docs.google.com/document/d/1P5laZqVYjtl_boSdpksT5LHOFjhm6CQLzWVx24UpXpM/edit

[gberche-orange]

workaround: have the broker support maintenance_info, and let the user perform a cf update-service --upgrade

[pivotal-marcela-campo]

Thanks for the update.

V2 is not in active development. As there is a workaround, we will close this issue for now.