(POOLER-93) Extend API endpoint to provide just what is needed

The status endpoint provides a lot of statistics. This commit extends it
by supporting a query parameter called 'view' which may contain one or
multiple comma separated names for the top-level statistics returned
in the JSON response. status is always returned.
Optional elements are capacity,queue,clone,boot,pools
Everything is returned when 'view' is not specified, which is
backwards compatible with the current behavior.

lib/vmpooler/api/v1.rb

@@ -176,23 +176,33 @@ module Vmpooler
     #     ],
     #     "uptime": 179585.9
     # }
+    #
+    # If the query parameter 'view' is provided, it will be used to select which top level
+    # element to compute and return. Select them by specifying them in a comma separated list.
+    # For example /status?view=capacity,boot
+    # would return only the "capacity" and "boot" statistics. "status" is always returned
+
     get "#{api_prefix}/status/?" do
       content_type :json
 
+      if params[:view]
+        views = params[:view].split(",")
+      end
+
       result = {
-        pools: {},
         status: {
           ok: true,
           message: 'Battle station fully armed and operational.'
         }
       }
 
-      result[:capacity] = get_capacity_metrics(pools, backend)
+      result[:capacity] = get_capacity_metrics(pools, backend) unless views and not views.include?("capacity")
-      result[:queue] = get_queue_metrics(pools, backend)
+      result[:queue] = get_queue_metrics(pools, backend) unless views and not views.include?("queue")
-      result[:clone] = get_task_metrics(backend, 'clone', Date.today.to_s)
+      result[:clone] = get_task_metrics(backend, 'clone', Date.today.to_s) unless views and not views.include?("clone")
-      result[:boot] = get_task_metrics(backend, 'boot', Date.today.to_s)
+      result[:boot] = get_task_metrics(backend, 'boot', Date.today.to_s) unless views and not views.include?("boot")
 
       # Check for empty pools
+      result[:pools] = {} unless views and not views.include?("pools")
       pools.each do |pool|
         # REMIND: move this out of the API and into the back-end
         ready   = backend.scard('vmpooler__ready__' + pool['name']).to_i
@@ -220,7 +230,7 @@ module Vmpooler
           result[:status][:ok] = false
           result[:status][:message] = "Found #{result[:status][:empty].length} empty pools."
         end
-      end
+      end unless views and not views.include?("pools")
 
       result[:status][:uptime] = (Time.now - Vmpooler::API.settings.config[:uptime]).round(1) if Vmpooler::API.settings.config[:uptime]
 

spec/integration/api/v1/status_spec.rb

@@ -118,5 +118,85 @@ describe Vmpooler::API::V1 do
         expect(result["status"]["empty"].sort).to eq(["pool1", "pool2", "pool3"])
       end
     end
+    describe 'GET /status with view query parameter' do
+      it 'returns capacity when specified' do
+        get "#{prefix}/status?view=capacity"
+
+        # of course /status doesn't conform to the weird standard everything else uses...
+        expect(last_response.header['Content-Type']).to eq('application/json')
+        result = JSON.parse(last_response.body)
+        expect(result["capacity"]).to_not be(nil)
+        expect(result["queue"]).to be(nil)
+        expect(result["clone"]).to be(nil)
+        expect(result["boot"]).to be(nil)
+        expect(result["pools"]).to be(nil)
+        expect(result["status"]).to_not be(nil)
+      end
+      it 'returns pools and queue when specified' do
+        get "#{prefix}/status?view=pools,queue"
+
+        # of course /status doesn't conform to the weird standard everything else uses...
+        expect(last_response.header['Content-Type']).to eq('application/json')
+        result = JSON.parse(last_response.body)
+        expect(result["capacity"]).to be(nil)
+        expect(result["queue"]).to_not be(nil)
+        expect(result["clone"]).to be(nil)
+        expect(result["boot"]).to be(nil)
+        expect(result["pools"]).to_not be(nil)
+        expect(result["status"]).to_not be(nil)
+      end
+      it 'does nothing with invalid view names' do
+        get "#{prefix}/status?view=clone,boot,invalidThingToView"
+
+        # of course /status doesn't conform to the weird standard everything else uses...
+        expect(last_response.header['Content-Type']).to eq('application/json')
+        result = JSON.parse(last_response.body)
+        expect(result["capacity"]).to be(nil)
+        expect(result["queue"]).to be(nil)
+        expect(result["clone"]).to_not be(nil)
+        expect(result["boot"]).to_not be(nil)
+        expect(result["pools"]).to be(nil)
+        expect(result["status"]).to_not be(nil)
+      end
+      it 'returns everything when view is not specified' do
+        get "#{prefix}/status"
+
+        # of course /status doesn't conform to the weird standard everything else uses...
+        expect(last_response.header['Content-Type']).to eq('application/json')
+        result = JSON.parse(last_response.body)
+        expect(result["capacity"]).to_not be(nil)
+        expect(result["queue"]).to_not be(nil)
+        expect(result["clone"]).to_not be(nil)
+        expect(result["boot"]).to_not be(nil)
+        expect(result["pools"]).to_not be(nil)
+        expect(result["status"]).to_not be(nil)
+      end
+      it 'returns everything when view is alone' do
+        get "#{prefix}/status?view"
+
+        # of course /status doesn't conform to the weird standard everything else uses...
+        expect(last_response.header['Content-Type']).to eq('application/json')
+        result = JSON.parse(last_response.body)
+        expect(result["capacity"]).to_not be(nil)
+        expect(result["queue"]).to_not be(nil)
+        expect(result["clone"]).to_not be(nil)
+        expect(result["boot"]).to_not be(nil)
+        expect(result["pools"]).to_not be(nil)
+        expect(result["status"]).to_not be(nil)
+      end
+      it 'returns status only when view is empty' do
+        get "#{prefix}/status?view="
+
+        # of course /status doesn't conform to the weird standard everything else uses...
+        expect(last_response.header['Content-Type']).to eq('application/json')
+        result = JSON.parse(last_response.body)
+        expect(result["capacity"]).to be(nil)
+        expect(result["queue"]).to be(nil)
+        expect(result["clone"]).to be(nil)
+        expect(result["boot"]).to be(nil)
+        expect(result["pools"]).to be(nil)
+        expect(result["status"]).to_not be(nil)
+      end
+    end
   end
 end