Even number across racks

SingularityUI/app/models/Request.coffee

@@ -1,7 +1,10 @@
 Model = require './model'
 
+Racks = require '../collections/Racks'
+
 pauseTemplate = require '../templates/vex/requestPause'
 scaleTemplate = require '../templates/vex/requestScale'
+scaleEvenNumbersTemplate = require '../templates/vex/requestScaleConfirmRacks'
 unpauseTemplate = require '../templates/vex/requestUnpause'
 runTemplate = require '../templates/vex/requestRun'
 removeTemplate = require '../templates/vex/requestRemove'
@@ -235,7 +238,46 @@ class Request extends Model
                 if !duration or (duration and @_validateDuration(duration, @promptPause, callback))
                     @pause(killTasks, duration, message).done callback
 
-    promptScale: (callback) =>
+    callScale: (data, bounce, incremental, message, duration, callback) =>
+        @scale(data).done =>
+            if bounce
+                @bounce({incremental}).done callback
+            else
+                callback()
+
+    promptScaleEvenNumberRacks: (scaleData) =>
+        vex.dialog.open
+            message: scaleEvenNumbersTemplate
+                instances: parseInt(scaleData.data.instances)
+                notOneInstance: parseInt(scaleData.data.instances) != 1
+                racks: @racks.length
+                notOneRack: @racks.length != 1
+                mod: scaleData.mod
+                modNotOne: scaleData.mod != 1
+                lower: parseInt(scaleData.data.instances) - scaleData.mod
+                higher: parseInt(scaleData.data.instances) + @racks.length - scaleData.mod
+                config: config
+            input: """
+
+            """
+            buttons: [
+                $.extend _.clone(vex.dialog.buttons.YES), text: "Scale"
+                vex.dialog.buttons.NO
+            ]
+            scaleData: scaleData # Not sure why this is necessary, callback for whatever reason doesn't have access to the function's variables
+            callback: (data) =>
+                return unless data
+                scaleData.data.instances = data.instances
+                @callScale scaleData.data, scaleData.bounce, scaleData.incremental, scaleData.message, scaleData.duration, scaleData.callback
+
+    checkScaleEvenNumberRacks: (data, bounce, incremental, message, duration, callback) =>
+        return 0 unless @attributes.request.rackSensitive
+        if not @racks
+            @racks = new Racks []
+            @racks.fetch { async: false }
+        return data.instances %% @racks.length
+
+    promptScale: (callback, stuff) =>
         vex.dialog.open
             message: "Enter the desired number of instances to run for request:"
             input:
@@ -261,11 +303,19 @@ class Request extends Model
                 message = $('.vex #scale-message').val()
                 duration = $('.vex #scale-expiration').val()
                 if !duration or (duration and @_validateDuration(duration, @promptScale, callback))
-                    @scale(data).done =>
-                        if bounce
-                            @bounce({incremental}).done callback
-                        else
-                            callback()
+                    mod = @checkScaleEvenNumberRacks data, bounce, incremental, message, duration, callback
+                    if mod
+                        @promptScaleEvenNumberRacks 
+                            callback: callback
+                            data: data
+                            mod: mod 
+                            bounce: bounce
+                            incremental: incremental
+                            message: message
+                            duration: duration 
+                    else
+                        @callScale data, bounce, incremental, message, duration, callback
+
 
     promptDisableHealthchecksDuration: (message, duration, callback) =>
         durationMillis = @_parseDuration(duration)

SingularityUI/app/templates/vex/requestScaleConfirmRacks.hbs

@@ -0,0 +1,41 @@
+<p>
+    We cannot distribute {{ instances }} 
+    {{#if notOneInstance}}
+        instances
+    {{else}}
+        instance
+    {{/if}}
+    evenly across our {{ racks }} 
+    {{#if notOneRack}}
+        racks.
+    {{else}}
+        rack.
+    {{/if}}
+    This will result in increased load on {{mod}} 
+    {{#if modNotOne}}
+        racks.
+    {{else}}
+        rack.
+    {{/if}}
+</p>
+<p>
+    We suggest scaling to 
+    {{#if lower}}
+        either <strong>{{ lower }}</strong> or
+    {{/if}}
+    <strong>{{ higher }}</strong> instances.
+    How many instances would you like to scale to?
+</p>
+<div id="instances">
+    {{#if lower}}
+        <input type="radio" name="instances" id="lower" value="{{ lower }}"> <label for="lower" id="lower-label">{{ lower }} instances</label><br/>
+    {{/if}}
+    <input type="radio" name="instances" id="default" value="{{ instances }}" checked> <label for="default" id="default-label">{{ instances }}
+    {{#if notOneInstance}}
+        instances
+    {{else}}
+        instance
+    {{/if}}
+    </label><br/>
+    <input type="radio" name="instances" id="higher" value="{{ higher }}"> <label for="higher" id="higher-label">{{ higher }} instances</label><br/>
+</div>