[AzureRT] Fix Get-AzureRmVM issue (#3375)

* Fix Get-AzureRmVM issue (#3372)

* Update AzureRM.Compute changelog.

Author: hyonholee

src/ResourceManager/Compute/ChangeLog.md

@@ -18,6 +18,7 @@
         - Additional information about change #1
 -->
 ## Current Release
+* Fix Get-AzureRmVM with -Status issue: Get-AzureRmVM throws an exception when Get-AzureRmVM lists multiple VMs and some of the VMs are deleted during Get-AzureRmVM is performed.
 * New parameters in New-AzureRmVMSqlServerAutoBackupConfig cmdlet to support Auto Backup for SQL Server 2016 VMs.
 	- BackupSystemDbs : Specifies if system databases should be added to Sql Server Managed Backup.
 	- BackupScheduleType : Specifies the type of managed backup schedule, manual or automated. If it's manual, schedule settings need to be specified.

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

@@ -32,6 +32,7 @@ public class GetAzureVMCommand : VirtualMachineBaseCmdlet
         protected const string ListVirtualMachineInResourceGroupParamSet = "ListVirtualMachineInResourceGroupParamSet";
         protected const string ListAllVirtualMachinesParamSet = "ListAllVirtualMachinesParamSet";
         protected const string ListNextLinkVirtualMachinesParamSet = "ListNextLinkVirtualMachinesParamSet";
+        private const string InfoNotAvailable = "Info Not Available";
 
         [Parameter(
            Mandatory = true,
@@ -101,23 +102,7 @@ public override void ExecuteCmdlet()
 
                     while (vmListResult != null)
                     {
-                        if (vmListResult.Body != null)
-                        {
-                            foreach (var item in vmListResult.Body)
-                            {
-                                var psItem = Mapper.Map<PSVirtualMachineListStatus>(vmListResult);
-                                psItem = Mapper.Map(item, psItem);
-                                if (this.Status.IsPresent)
-                                {
-                                    // Call additional Get InstanceView of each VM to get the power states of all VM.
-                                    var state = this.VirtualMachineClient.Get(psItem.ResourceGroupName, psItem.Name, InstanceViewExpand);
-                                    var psstate = state.ToPSVirtualMachineInstanceView(psItem.ResourceGroupName, psItem.Name);
-                                    psItem.PowerState = psstate.Statuses[1].DisplayStatus;
-                                }
-                                psItem.DisplayHint = this.DisplayHint;
-                                psResultListStatus.Add(psItem);
-                            }
-                        }
+                        psResultListStatus = GetPowerstate(vmListResult, psResultListStatus);
 
                         if (!string.IsNullOrEmpty(vmListResult.Body.NextPageLink))
                         {
@@ -171,25 +156,9 @@ public override void ExecuteCmdlet()
                     AzureOperationResponse<IPage<VirtualMachine>> vmListResult = null;
                     vmListResult = this.VirtualMachineClient.ListWithHttpMessagesAsync(this.ResourceGroupName)
                             .GetAwaiter().GetResult();
-                    var psResultListStatus = new List<PSVirtualMachineListStatus>();
-                    if (vmListResult.Body != null)
-                    {
-                        foreach (var item in vmListResult.Body)
-                        {
-                            var psItem = Mapper.Map<PSVirtualMachineListStatus>(vmListResult);
-                            psItem = Mapper.Map(item, psItem);
 
-                            if (this.Status.IsPresent)
-                            {
-                                // Call additional Get InstanceView of each VM to get the power states of all VM.
-                                var state = this.VirtualMachineClient.Get(this.ResourceGroupName, psItem.Name, InstanceViewExpand);
-                                var psstate = state.ToPSVirtualMachineInstanceView(this.ResourceGroupName, psItem.Name);
-                                psItem.PowerState = psstate.Statuses[1].DisplayStatus;
-                            }
-                            psItem.DisplayHint = this.DisplayHint;
-                            psResultListStatus.Add(psItem);
-                        }
-                    }
+                    var psResultListStatus = new List<PSVirtualMachineListStatus>();
+                    psResultListStatus = GetPowerstate(vmListResult, psResultListStatus);
 
                     if (this.Status.IsPresent)
                     {
@@ -208,5 +177,53 @@ public override void ExecuteCmdlet()
                 }
             });
         }
+
+        private List<PSVirtualMachineListStatus> GetPowerstate(
+            AzureOperationResponse<IPage<VirtualMachine>> vmListResult,
+            List<PSVirtualMachineListStatus> psResultListStatus)
+        {
+            if (vmListResult.Body != null)
+            {
+                foreach (var item in vmListResult.Body)
+                {
+                    var psItem = Mapper.Map<PSVirtualMachineListStatus>(vmListResult);
+                    psItem = Mapper.Map(item, psItem);
+                    if (this.Status.IsPresent)
+                    {
+                        VirtualMachine state = null;
+                        try
+                        {
+                            // Call additional Get InstanceView of each VM to get the power states of all VM.
+                            state = this.VirtualMachineClient.Get(psItem.ResourceGroupName, psItem.Name, InstanceViewExpand);
+                        }
+                        catch
+                        {
+                            // Swallow any exception during getting instance view information.
+                        }
+
+                        if (state == null)
+                        {
+                            psItem.PowerState = InfoNotAvailable;
+                        }
+                        else
+                        {
+                            var psstate = state.ToPSVirtualMachineInstanceView(psItem.ResourceGroupName, psItem.Name);
+                            if (psstate != null && psstate.Statuses != null && psstate.Statuses.Count > 1)
+                            {
+                                psItem.PowerState = psstate.Statuses[1].DisplayStatus;
+                            }
+                            else
+                            {
+                                psItem.PowerState = InfoNotAvailable;
+                            }
+                        }
+                    }
+                    psItem.DisplayHint = this.DisplayHint;
+                    psResultListStatus.Add(psItem);
+                }
+            }
+
+            return psResultListStatus;
+        }
     }
 }