Question 95571 in Amazon Web Sevices Question posted in
The official Amazon Web Services documentation can be found here.

Force "Replace" update behavior on changes to Metadata for AWS::EC2::Instance resources? – Amazon web services

Is it possible to force the "Replace" update behavior on changes to the Metadata property for AWS::EC2::Instance resources?

I have an EC2 instance that does not have any important state (so I don’t care about its disks and other state getting deleted). The instance has a number of AWS::CloudFormation::Init scripts and files which are used to set up the instance upon creation. However, these scripts do not run again on update and nor would it make sense for them to run again on update.

The problem I am having is that sometimes I want to change something about the instance, which usually consists of modifying the AWS::CloudFormation::Init scripts and/or files. What I’d like to have happen is when I update the CloudFormation stack with a change to these Metadata properties, then I’d like the instance to be deleted and recreated (i.e. the "Replace" update behavior with UpdateReplacePolicy: Delete).

Here is what my resource looks like:

  GatewayInstance:
    Type: 'AWS::EC2::Instance'
    DeletionPolicy: Delete
    UpdateReplacePolicy: Delete
    Properties:
      # ...
    Metadata:
      AWS::CloudFormation::Init:
        # When this changes I want GatewayInstance to be deleted and recreated

Is this possible?

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    It is a bit of a hack, but I did find a solution.

    Changing any of the following properties force replacement of the instance:

    AvailabilityZone
CpuOptions
ElasticGpuSpecifications
ElasticInferenceAccelerators
EnclaveOptions
HibernationOptions
HostResourceGroupArn
ImageId
Ipv6AddressCount
Ipv6Addresses
KeyName
LaunchTemplate
LicenseSpecifications
NetworkInterfaces
PlacementGroupName
PrivateIpAddress
SecurityGroups
SubnetId

    So, I simply created two identical key pairs and when I toggle KeyName between them and update the stack this forces the recreation of the physical resources. Et viola.


  2. 0

    Sadly its not possible as explained in the docs:

    During a stack update, you cannot update the Metadata section by itself. You can update it only when you include changes that add, modify, or delete resources.

    You maybe could create your own custom resource to apply the changes that you make in Metadata.

    The alternative is not use use Metadata at all.

    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search