vcsim: add support for cloning HostSystems

The simulator.ClusterComputeResource.AddHost method uses the compiled in esx.HostSystem template by default,
as does simulator.AddStandaloneHost.
With this change, if the HostConnectSpec.UserName is that of a HostSystem.Name in the given Cluster or
of a standalone host, use that HostSystem as the template.

govc/test/vcsim.bats

@@ -477,6 +477,16 @@ EOF
   objs=$(govc find / | wc -l)
   assert_equal 23 "$objs"
 
+  run govc cluster.add -cluster DC0_C0 -hostname DC0_C0_H0-clone -username DC0_C0_H0 -password pass -noverify
+  assert_success
+  objs=$(govc find / | wc -l)
+  assert_equal 24 "$objs"
+
+  run govc host.add -hostname DC0_H0-clone -username DC0_H0 -password pass -noverify
+  assert_success
+  objs=$(govc find / | wc -l)
+  assert_equal 27 "$objs" # ComputeResource + ResourcePool + HostSystem
+
   run govc host.portgroup.add -host DC0_H0 -vswitch vSwitch0 bridge
   assert_success # issue #2016
 }

simulator/cluster_compute_resource.go

@@ -54,16 +54,25 @@ func (add *addHost) Run(task *Task) (types.AnyType, types.BaseMethodFault) {
 		return nil, &types.NoHost{}
 	}
 
-	host := NewHostSystem(esx.HostSystem)
+	cr := add.ClusterComputeResource
+	template := esx.HostSystem
+
+	if h := task.ctx.Map.FindByName(spec.UserName, cr.Host); h != nil {
+		// "clone" an existing host from the inventory
+		template = h.(*HostSystem).HostSystem
+		template.Vm = nil
+	} else {
+		template.Network = cr.Network[:1] // VM Network
+	}
+
+	host := NewHostSystem(template)
 	host.configure(spec, add.req.AsConnected)
 
-	cr := add.ClusterComputeResource
 	task.ctx.Map.PutEntity(cr, task.ctx.Map.NewEntity(host))
 	host.Summary.Host = &host.Self
 
 	cr.Host = append(cr.Host, host.Reference())
 	addComputeResource(cr.Summary.GetComputeResourceSummary(), host)
-	host.Network = cr.Network[:1] // VM Network
 
 	return host.Reference(), nil
 }

simulator/host_system.go

@@ -58,11 +58,15 @@ func NewHostSystem(host mo.HostSystem) *HostSystem {
 	hs.Summary.Runtime = &hs.Runtime
 	hs.Summary.Runtime.BootTime = &now
 
+	// shallow copy Summary.Hardware, as each host will be assigned its own .Uuid
 	hardware := *host.Summary.Hardware
 	hs.Summary.Hardware = &hardware
 
-	info := *esx.HostHardwareInfo
-	hs.Hardware = &info
+	if hs.Hardware == nil {
+		// shallow copy Hardware, as each host will be assigned its own .Uuid
+		info := *esx.HostHardwareInfo
+		hs.Hardware = &info
+	}
 
 	cfg := new(types.HostConfigInfo)
 	deepCopy(hs.Config, cfg)
@@ -189,8 +193,20 @@ func CreateStandaloneHost(ctx *Context, f *Folder, spec types.HostConnectSpec) (
 		return nil, &types.NoHost{}
 	}
 
+	template := esx.HostSystem
+	network := ctx.Map.getEntityDatacenter(f).defaultNetwork()
+
+	if p := ctx.Map.FindByName(spec.UserName, f.ChildEntity); p != nil {
+		cr := p.(*mo.ComputeResource)
+		h := ctx.Map.Get(cr.Host[0])
+		// "clone" an existing host from the inventory
+		template = h.(*HostSystem).HostSystem
+		template.Vm = nil
+		network = cr.Network
+	}
+
 	pool := NewResourcePool()
-	host := NewHostSystem(esx.HostSystem)
+	host := NewHostSystem(template)
 	host.configure(spec, false)
 
 	summary := new(types.ComputeResourceSummary)
@@ -210,7 +226,7 @@ func CreateStandaloneHost(ctx *Context, f *Folder, spec types.HostConnectSpec) (
 	ctx.Map.PutEntity(cr, ctx.Map.NewEntity(pool))
 
 	cr.Name = host.Name
-	cr.Network = ctx.Map.getEntityDatacenter(f).defaultNetwork()
+	cr.Network = network
 	cr.Host = append(cr.Host, host.Reference())
 	cr.ResourcePool = &pool.Self