A Target state is created from a Current state.

Author: sergey-shandar

src/ResourceManager/Common/Commands.Common.Strategies/Commands.Common.Strategies.csproj

@@ -76,6 +76,7 @@
     <Compile Include="GetAsyncOperation.cs" />
     <Compile Include="GetAsyncParams.cs" />
     <Compile Include="IClient.cs" />
+    <Compile Include="IReport.cs" />
     <Compile Include="IResourceConfig.cs" />
     <Compile Include="IResourceConfigVisitor.cs" />
     <Compile Include="IResourceStrategy.cs" />

src/ResourceManager/Common/Commands.Common.Strategies/CreateOrUpdateAsyncOperation.cs

@@ -19,12 +19,11 @@ public static class CreateOrUpdateAsyncOperation
         public static async Task<IState> CreateOrUpdateAsync<Model>(
             this IResourceConfig<Model> config,
             IClient client,
-            IState current,
             IState target,
             CancellationToken cancellationToken)
             where Model : class
         {
-            var visitor = new CreateAsyncVisitor(client, current, target, cancellationToken);
+            var visitor = new CreateAsyncVisitor(client, target, cancellationToken);
             await visitor.GetOrAdd(config);
             return visitor.Result;
         }
@@ -33,10 +32,10 @@ sealed class CreateAsyncVisitor : AsyncOperationVisitor
         {
             public override async Task<object> Visit<Model>(ResourceConfig<Model> config)
             {
-                var current = Current.GetOrNull(config);
-                if (current != null)
+                var target = Target.GetOrNull(config);
+                if (target == null)
                 {
-                    return current;
+                    return null;
                 }
                 var tasks = config.Dependencies.Select(GetOrAddUntyped);
                 await Task.WhenAll(tasks);
@@ -52,22 +51,23 @@ public override async Task<object> Visit<Model>(ResourceConfig<Model> config)
             public override async Task<object> Visit<Model, ParentModel>(
                 NestedResourceConfig<Model, ParentModel> config)
             {
+                var target = Target.GetOrNull(config);
+                if (target == null)
+                {
+                    return null;
+                }
                 var parent = await GetOrAdd(config.Parent);
                 return config.Policy.Get(parent, config.Name);
             }
 
             public CreateAsyncVisitor(
                 IClient client,
-                IState current,
                 IState target,
                 CancellationToken cancellationToken)
                 : base(client, cancellationToken)
             {
-                Current = current;
                 Target = target;
             }
-
-            IState Current { get; }
 
             IState Target { get; }
         }

src/ResourceManager/Common/Commands.Common.Strategies/IReport.cs

@@ -0,0 +1,8 @@
+namespace Microsoft.Azure.Commands.Common.Strategies
+{
+    public interface IReport
+    {
+        void Start(IResourceConfig config);
+        void Done(IResourceConfig config);
+    }
+}

src/ResourceManager/Common/Commands.Common.Strategies/IState.cs

@@ -7,5 +7,7 @@ public interface IState
     {
         Model GetOrNull<Model>(IResourceConfig<Model> config)
             where Model : class;
+
+        object GetOrNullUntyped(IResourceConfig config);
     }
 }

src/ResourceManager/Common/Commands.Common.Strategies/State.cs

@@ -5,9 +5,12 @@ namespace Microsoft.Azure.Commands.Common.Strategies
 {
     sealed class State : IState
     {
+        public object GetOrNullUntyped(IResourceConfig config)
+            => Map.GetOrNull(config.DefaultIdStr());
+
         public Model GetOrNull<Model>(IResourceConfig<Model> config)
             where Model : class
-            => Map.GetOrNull(config.DefaultIdStr()) as Model;
+            => GetOrNullUntyped(config) as Model;
 
         public Model GetOrAdd<Model>(IResourceConfig<Model> config, Func<Model> f)
             where Model : class

src/ResourceManager/Common/Commands.Common.Strategies/TargetState.cs

@@ -1,22 +1,30 @@
-namespace Microsoft.Azure.Commands.Common.Strategies
+using System.Linq;
+
+namespace Microsoft.Azure.Commands.Common.Strategies
 {
     public static class TargetState
     {
         public static IState GetTargetState<Model>(
             this IResourceConfig<Model> config,
+            IState current,
             string subscription, 
             string location)
             where Model : class
         {
-            var visitor = new Visitor(subscription, location);
-            visitor.Get(config);
+            var visitor = new Visitor(current, subscription, location);
+            // create a target model onyl if the resource doesn't exist.
+            if (current.GetOrNull(config) == null)
+            {
+                visitor.Get(config);
+            }
             return visitor.Result;
         }
 
         sealed class Visitor : IResourceConfigVisitor<object>
         {
-            public Visitor(string subscription, string location)
+            public Visitor(IState current, string subscription, string location)
             {
+                Current = current;
                 Subscription = subscription;
                 Location = location;
             }
@@ -28,10 +36,13 @@ public Model Get<Model>(IResourceConfig<Model> config)
                 where Model : class
                 => GetUntyped(config) as Model;
 
-            public object Visit<Model>(ResourceConfig<Model> config) 
+            public object Visit<Model>(ResourceConfig<Model> config)
                 where Model : class
             {
-                foreach (var d in config.Dependencies)
+                // create a dependency target model only if the dependency resource doesn't exist.
+                foreach (var d in config
+                    .Dependencies
+                    .Where(d => Current.GetOrNullUntyped(d) == null))
                 {
                     GetUntyped(d);
                 }
@@ -54,6 +65,8 @@ public object Visit<Model, ParentModel>(
 
             string Location { get; }
 
+            IState Current { get; }
+
             public State Result { get; } = new State();
         }
     }

src/ResourceManager/Compute/Commands.Compute/VirtualMachine/Operation/NewAzureVMCommand.cs

@@ -181,23 +181,23 @@ public void StrategyExecuteCmdlet()
 
             //
             var client = new Client(DefaultProfile.DefaultContext);
-            var state = virtualMachine
+            var current = virtualMachine
                 .GetAsync(client, new CancellationToken())
                 .GetAwaiter()
                 .GetResult();
 
             if (Location == null)
             {
-                Location = state.GetLocation(virtualMachine);
+                Location = current.GetLocation(virtualMachine);
                 if (Location == null)
                 {
                     Location = "eastus";
                 }
             }
 
-            var target = virtualMachine.GetTargetState(client.SubscriptionId, Location);
+            var target = virtualMachine.GetTargetState(current, client.SubscriptionId, Location);
             var result = virtualMachine
-                .CreateOrUpdateAsync(client, state, target, new CancellationToken())
+                .CreateOrUpdateAsync(client, target, new CancellationToken())
                 .GetAwaiter()
                 .GetResult();
         }