Inform user of the need to scale up when enabling HA on a scaled application

Bug 1256952
https://bugzilla.redhat.com/show_bug.cgi?id=1256952

When an application with more than one gear ha HA enabled, a short message will now be given stating the possible need to scale the application up to actually receive the second haproxy instance.

In addition to a adding a new test, the `app_spec.rb` now requires 'net/ssh/multi' to allow the spec to be run on its own outside of the RHC spec test suite. This has been resolved.

Author: tiwillia

lib/rhc/commands/app.rb

@@ -376,9 +376,37 @@ def tidy(app)
     syntax "<app> [--namespace NAME]"
     takes_application :argument => true
     def enable_ha(app)
-      app_action :enable_ha
+      rest_app = find_app
+
+      scaleup_needed = false
+      cant_scale_up = false
+      gear_groups = rest_app.gear_groups
+      gear_groups.each do |gg|
+        if gg.attributes["scales_from"] and gg.attributes["scales_from"] > 1
+          scaleup_needed = true
+          if gg.attributes["scales_to"] and rest_app.gear_count == gg.attributes["scales_to"]
+            cant_scale_up = true
+          end
+        end
+      end
 
-      results { say "#{app} is now highly available" }
+      rest_app.send :enable_ha
+      results do
+        # If the application was already scaled, a scale up may be required.
+        if scaleup_needed
+          say "#{app} is now configured to be highly available"
+          if cant_scale_up
+            msg = "You will need to scale down the application, then scale back up to create an additional " +
+              "haproxy instance:\n  rhc app scale-down #{rest_app.name} && rhc app scale-up #{rest_app.name}"
+          else
+            msg = "You will need to scale up the application to create an additional haproxy instance:\n" +
+              "  rhc app scale-up #{rest_app.name}"
+          end
+          warn msg
+        else
+          say "#{app} is now highly available"
+        end
+      end
       0
     end
 

spec/rhc/commands/app_spec.rb

@@ -4,6 +4,7 @@
 require 'rhc/config'
 require 'rhc/servers'
 require 'resolv'
+require 'net/ssh/multi'
 
 describe RHC::Commands::App do
   let!(:rest_client){ MockRestClient.new }
@@ -933,6 +934,22 @@
     end
   end
 
+  describe 'app enable-ha on scaled application' do
+    before do
+      @domain = rest_client.add_domain("mockdomain")
+      @app = @domain.add_application("app1", "mock_type", true)
+      @app.add_cartridge('mock_cart-1')
+      @app.scale_up
+    end
+
+    let(:arguments) { ['app', 'enable-ha', 'app1'] }
+
+    it "should suggest scaling up to receive additional haproxy instances" do
+      run_output.should match(/You will need to scale/)
+      expect{ run }.to exit_with_code(0)
+    end
+  end
+
   describe "#create_app" do
     it("should list cartridges when a server error happens") do
       subject.should_receive(:list_cartridges)