Implement "/v3/spaces/#{space.guid}/usage_summary" endpoint

app/controllers/v3/spaces_controller.rb

@@ -1,5 +1,6 @@
 require 'presenters/v3/paginated_list_presenter'
 require 'presenters/v3/space_presenter'
+require 'presenters/v3/space_usage_summary_presenter'
 require 'messages/space_create_message'
 require 'messages/space_delete_unmapped_routes_message'
 require 'messages/space_update_message'
@@ -211,6 +212,14 @@ def list_members
     raise CloudController::Errors::ApiError.new_from_details('UaaUnavailable')
   end
 
+  def show_usage_summary
+    space = fetch_space(hashed_params[:guid])
+    space_not_found! unless space
+    space_not_found! unless permission_queryer.can_read_from_space?(space.id, space.organization_id)
+
+    render status: :ok, json: Presenters::V3::SpaceUsageSummaryPresenter.new(space)
+  end
+
   private
 
   def fetch_organization(guid)

app/models/runtime/space.rb

@@ -269,6 +269,10 @@ def find_visible_service_instance_by_name(name)
       (shared | source).first
     end
 
+    def number_service_keys
+      ServiceKey.join(:service_instances, id: :service_instance_id).where(service_instances__space_id: id).count
+    end
+
     def self.user_visibility_filter(user)
       {
         spaces__id: user.space_developer_space_ids.
@@ -328,6 +332,14 @@ def members
       User.dataset.where(id: Role.where(space_id: id).distinct.select(:user_id))
     end
 
+    def memory_used
+      started_app_memory + running_task_memory
+    end
+
+    def running_and_pending_tasks_count
+      tasks_dataset.where(state: [TaskModel::PENDING_STATE, TaskModel::RUNNING_STATE]).count
+    end
+
     private
 
     def has_manager?(user)
@@ -339,7 +351,6 @@ def has_auditor?(user)
     end
 
     def memory_remaining
-      memory_used = started_app_memory + running_task_memory
       space_quota_definition.memory_limit - memory_used
     end
 
@@ -363,10 +374,6 @@ def started_app_log_rate_limit
       processes_dataset.where(state: ProcessModel::STARTED).sum(Sequel.*(:log_rate_limit, :instances)) || 0
     end
 
-    def running_and_pending_tasks_count
-      tasks_dataset.where(state: [TaskModel::PENDING_STATE, TaskModel::RUNNING_STATE]).count
-    end
-
     def validate_isolation_segment_set(isolation_segment_model)
       isolation_segment_guids = organization.isolation_segment_models.map(&:guid)
       return if isolation_segment_guids.include?(isolation_segment_model.guid)

app/presenters/v3/space_usage_summary_presenter.rb

@@ -0,0 +1,42 @@
+require 'presenters/v3/base_presenter'
+
+module VCAP::CloudController::Presenters::V3
+  class SpaceUsageSummaryPresenter < BasePresenter
+    def to_hash
+      {
+        usage_summary: {
+          started_instances: started_instances,
+          memory_in_mb: space.memory_used,
+          routes: space.routes_dataset.count,
+          service_instances: space.service_instances_dataset.count,
+          reserved_ports: VCAP::CloudController::SpaceReservedRoutePorts.new(space).count,
+          domains: space.organization.owned_private_domains_dataset.count,
+          per_app_tasks: space.running_and_pending_tasks_count,
+          service_keys: space.number_service_keys
+        },
+        links: build_links
+      }
+    end
+
+    private
+
+    def space
+      @resource
+    end
+
+    def started_instances
+      space.processes_dataset.where(state: VCAP::CloudController::ProcessModel::STARTED).sum(:instances) || 0
+    end
+
+    def build_links
+      {
+        self: {
+          href: url_builder.build_url(path: "/v3/spaces/#{space.guid}/usage_summary")
+        },
+        space: {
+          href: url_builder.build_url(path: "/v3/spaces/#{space.guid}")
+        }
+      }
+    end
+  end
+end

config/routes.rb

@@ -276,6 +276,7 @@
   patch '/spaces/:guid', to: 'spaces_v3#update'
   delete 'spaces/:guid', to: 'spaces_v3#destroy'
   delete 'spaces/:guid/routes', to: 'spaces_v3#delete_unmapped_routes'
+  get '/spaces/:guid/usage_summary', to: 'spaces_v3#show_usage_summary'
   get '/spaces/:guid/relationships/isolation_segment', to: 'spaces_v3#show_isolation_segment'
   patch '/spaces/:guid/relationships/isolation_segment', to: 'spaces_v3#update_isolation_segment'
   get '/spaces/:guid/users', to: 'spaces_v3#list_members'

docs/v3/source/includes/api_resources/_spaces.erb

@@ -145,3 +145,26 @@
   ]
 }
 <% end %>
+
+<% content_for :space_usage_summary do %>
+{
+  "usage_summary": {
+    "started_instances": 3,
+    "memory_in_mb": 3072,
+    "routes": 3,
+    "service_instances": 2,
+    "reserved_ports": 1,
+    "domains": 1,
+    "per_app_tasks": 0,
+    "service_keys": 1
+  },
+  "links": {
+    "self": {
+      "href": "https://api.example.org/v3/spaces/f47ac10b-58cc-4372-a567-0e02b2c3d479/usage_summary"
+    },
+    "organization": {
+      "href": "https://api.example.org/v3/spaces/f47ac10b-58cc-4372-a567-0e02b2c3d479"
+    }
+  }
+}
+<% end %>

docs/v3/source/includes/resources/spaces/_get_usage_summary.md.erb

@@ -0,0 +1,39 @@
+### Get space usage summary
+
+```
+Example Request
+```
+
+```shell
+curl "https://api.example.org/v3/spaces/[guid]/usage_summary" \
+  -X GET \
+  -H "Authorization: bearer [token]"
+```
+
+```
+Example Response
+```
+
+```http
+HTTP/1.1 200 OK
+Content-Type: application/json
+
+<%= yield_content :space_usage_summary, '/v3/spaces/:guid/usage_summary' %>
+```
+
+This endpoint retrieves a usage summary for the specified space. It provides aggregated data about the space's resource usage, such as memory, routes and services.
+
+#### Definition
+`GET /v3/spaces/:guid/usage_summary`
+
+#### Permitted roles
+|
+--- |
+Admin |
+Admin Read-Only |
+Global Auditor |
+Org Manager |
+Space Auditor |
+Space Developer |
+Space Manager |
+Space Supporter |

docs/v3/source/includes/upgrade_guide/conceptual_changes/_resource_summaries.md

@@ -71,5 +71,5 @@ in the response body.
 #### Usage summary endpoints
 
 There are still a couple of endpoints in V3 that provide a basic summary of
-instance and memory usage. See the [org summary](#get-usage-summary) and
+instance and memory usage. See the [org summary](#get-usage-summary), [space summary](#get-space-usage-summary) and
 [platform summary](#get-platform-usage-summary) endpoints.

docs/v3/source/index.html.md

@@ -354,6 +354,7 @@ includes:
   - resources/spaces/update
   - resources/spaces/delete
   - resources/spaces/get_assigned_isolation_segment
+  - resources/spaces/get_usage_summary
   - resources/spaces/manage_isolation_segment
   - resources/spaces/list_users
   - resources/space_features/header

spec/unit/controllers/v3/spaces_controller_spec.rb

@@ -952,4 +952,34 @@
       end
     end
   end
+
+  describe '#show_usage_summary' do
+    let(:user) { set_current_user(VCAP::CloudController::User.make) }
+
+    let!(:org) { VCAP::CloudController::Organization.make(name: 'Lyle\'s Farm') }
+    let!(:space) { VCAP::CloudController::Space.make(name: 'Chicken', organization: org) }
+
+    context 'when the user has permissions to read from the space' do
+      before { allow_user_read_access_for(user, orgs: [org], spaces: [space]) }
+
+      it 'succeeds' do
+        get :show_usage_summary, params: { guid: space.guid }
+
+        expect(response).to have_http_status(:ok)
+        expect(response.body).to include 'usage_summary'
+      end
+    end
+
+    context 'when the user does not have permissions to read from the space' do
+      before { allow_user_read_access_for(user, orgs: [], spaces: []) }
+
+      it 'throws ResourceNotFound error' do
+        get :show_usage_summary, params: { guid: space.guid }
+
+        expect(response).to have_http_status(:not_found)
+        expect(response.body).to include 'ResourceNotFound'
+        expect(response.body).to include 'Space not found'
+      end
+    end
+  end
 end

spec/unit/presenters/v3/space_usage_summary_presenter_spec.rb

@@ -0,0 +1,67 @@
+require 'spec_helper'
+require 'presenters/v3/space_usage_summary_presenter'
+
+module VCAP::CloudController::Presenters::V3
+  RSpec.describe SpaceUsageSummaryPresenter do
+    let(:org) { VCAP::CloudController::Organization.make }
+    let(:space) { VCAP::CloudController::Space.make(organization: org) }
+
+    context 'empty space' do
+      describe '#to_hash' do
+        let(:result) { SpaceUsageSummaryPresenter.new(space).to_hash }
+
+        it 'presents the space usage summary as json' do
+          expect(result[:usage_summary][:started_instances]).to eq(0)
+          expect(result[:usage_summary][:memory_in_mb]).to eq(0)
+          expect(result[:usage_summary][:routes]).to eq(0)
+          expect(result[:usage_summary][:service_instances]).to eq(0)
+          expect(result[:usage_summary][:reserved_ports]).to eq(0)
+          expect(result[:usage_summary][:domains]).to eq(0)
+          expect(result[:usage_summary][:per_app_tasks]).to eq(0)
+          expect(result[:usage_summary][:service_keys]).to eq(0)
+
+          expect(result[:links][:self][:href]).to match(%r{/v3/spaces/#{space.guid}/usage_summary$})
+          expect(result[:links][:space][:href]).to match(%r{/v3/spaces/#{space.guid}$})
+        end
+      end
+    end
+
+    context 'space with instances, routes and services' do
+      before do
+        router_group = double('router_group', type: 'tcp', reservable_ports: [4444])
+        routing_api_client = double('routing_api_client', router_group: router_group, enabled?: true)
+        allow(CloudController::DependencyLocator).to receive(:instance).and_return(double(:api_client, routing_api_client:))
+      end
+
+      let(:app_model) { VCAP::CloudController::AppModel.make(name: 'App Model', space: space) }
+      let!(:process) { VCAP::CloudController::ProcessModel.make(:process, state: VCAP::CloudController::ProcessModel::STARTED, memory: 512, app: app_model) }
+      let!(:task) { VCAP::CloudController::TaskModel.make(app: app_model, state: VCAP::CloudController::TaskModel::RUNNING_STATE, memory_in_mb: 512) }
+      let(:shared_domain) { VCAP::CloudController::SharedDomain.make(router_group_guid: '123') }
+      let!(:private_domain) { VCAP::CloudController::PrivateDomain.make(owning_organization: org) }
+      let!(:route) { VCAP::CloudController::Route.make(host: '', domain: shared_domain, space: space, port: 4444) }
+      let(:broker) { VCAP::CloudController::ServiceBroker.make }
+      let(:service) { VCAP::CloudController::Service.make(service_broker: broker) }
+      let(:service_plan) { VCAP::CloudController::ServicePlan.make(service: service, public: true) }
+      let(:service_instance) { VCAP::CloudController::ManagedServiceInstance.make(space:, service_plan:) }
+      let!(:service_key) { VCAP::CloudController::ServiceKey.make(service_instance:) }
+
+      describe '#to_hash' do
+        let(:result) { SpaceUsageSummaryPresenter.new(space).to_hash }
+
+        it 'presents the space usage summary as json' do
+          expect(result[:usage_summary][:started_instances]).to eq(1)
+          expect(result[:usage_summary][:memory_in_mb]).to eq(1024)
+          expect(result[:usage_summary][:routes]).to eq(1)
+          expect(result[:usage_summary][:service_instances]).to eq(1)
+          expect(result[:usage_summary][:reserved_ports]).to eq(1)
+          expect(result[:usage_summary][:domains]).to eq(1)
+          expect(result[:usage_summary][:per_app_tasks]).to eq(1)
+          expect(result[:usage_summary][:service_keys]).to eq(1)
+
+          expect(result[:links][:self][:href]).to match(%r{/v3/spaces/#{space.guid}/usage_summary$})
+          expect(result[:links][:space][:href]).to match(%r{/v3/spaces/#{space.guid}$})
+        end
+      end
+    end
+  end
+end