How to launch an EC2 instance into a VPC with a public IP address in PowerShell? - powershell

Question

I have been trying to use the following script, but haven't been successful:
$Ami=Get-EC2ImageByName WINDOWS_2012_BASE
New-EC2Instance -ImageId $Ami[0].ImageId -MinCount 1 -MaxCount 1 -KeyName uckey -InstanceType `
t1.micro -SubnetId subnet-56738b33 -AssociatePublicIp $true
The error is:
New-EC2Instance : Object reference not set to an instance of an object.
At line:1 char:1
+ New-EC2Instance -ImageId $Ami[0].ImageId -MinCount 1 -MaxCount 1 -KeyName uckey ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (Amazon.PowerShe...2InstanceCmdlet:NewEC2InstanceCmdlet)
[New-EC2Instance], InvalidOperationException
+ FullyQualifiedErrorId : System.NullReferenceException,Amazon.PowerShell.Cmdlets.EC2.NewEC2InstanceC
mdlet
The problem is about the parameter -AssociatePublicIp without it, the script works.
Thanks for reading

Answer 1

As of AWS PowerShell version 2.1.3.0, this bug has been corrected.
I was able to execute this script:
New-EC2Instance -ImageId $Ami[0].ImageId -MinCount 1 -MaxCount 1 -KeyName uckey -InstanceType `
t1.micro -SubnetId subnet-56738b33 -AssociatePublicIp $true

Answer 2

I ran into the same problem, and a possible workaround while still using PowerShell is to create the network interface first, and then associating it with the instance:
$subnetId = "subnet-56738b33"
$keyName = "uckey"
$instanceType = "t1.micro"
$Ami = Get-EC2ImageByName WINDOWS_2012_BASE
$ImageId = $Ami[0].ImageId
$networkInterface = New-EC2NetworkInterface -SubnetId $subnetId -Description "Primary network interface"
$interfaceSpec = New-Object Amazon.EC2.Model.InstanceNetworkInterfaceSpecification -property #{"NetworkInterfaceId"=$networkInterface.NetworkInterfaceId}
$reservation = New-EC2Instance -ImageId $ImageId -MinCount 1 -MaxCount 1 -InstanceType $instanceType -KeyName $keyName -NetworkInterfaces $interfaceSpec
The InstanceNetworkInterfaceSpecification has a property to indicate if the interface needs a public IP address (see the docs)

Answer 3

I suspect this to be a bug in the AWS Tools for Windows PowerShell. As already commented, running the semantically identical command with the AWS Command Line Interface instead yields the desired result:
$ aws ec2 run-instances --image-id $ami.Imageid --count 1:1 --instance-type t1.micro `
--key-name uckey --subnet-id subnet-56738b33 --associate-public-ip-address
Beware of the slight syntax difference for --count and --associate-public-ip-address, the latter doesn't require a value, rather comprises the flag in itself, i.e. [--associate-public-ip-address | --no-associate-public-ip-address], see run-instances.
This is also confirmed by an (unfortunately unanswered) inquiry in the AWS Forum for PowerShell scripting, see Unable to get New-EC2Instance to honour -AssociatePublicIP.
Accordingly, your best bet to get this resolved might be to bump that thread and hope for a response from the AWS team. Meanwhile you can work around the issue by means of scripting the operation via the AWS CLI instead.