CODEWITHSUNDEEP
amazon-web-servicesaws-cloudformation
user2175783
user2175783

Reputation: 1441

Conditional value of ssm parameter in cloudformation template

I have a cloudformation template that uses a few ssm parameters. Those parameters are only defined in a given region for a given account. I would like to use the ssm parameters if they are defined and not use them if they are not defined in a given region (perhaps default to a certain string value like "undefined").

Something like this

Parameters:
  anssmparameter:
    Type: AWS::SSM::Parameter::Value<String>
    # if ssmparam is defined
    Default: ssmparam
    # else ssmparam is not defined use a different default
    Default: "a placeholder value"
    Description: some description

Is this possible in cloudformation? I have researched a bit and it seems this is not possible?

The close I have seen is this which essentially says it is not possible

Is this possible to have optional SSM parameter?

Upvotes: 2

Views: 1604

Answers (2)

misschak
misschak

Reputation: 11

You can use dynamic references to resolve on runtime if given parameter value

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/dynamic-references.html

Parameters:
  anssmparameter:
    Type: String
  placeholdervalue:
    Type: String
    Default: 'a placeholder value'

Conditions:
  toResolveSSMParam: !Not [!Equals [!Sub '${anssmparameter}', '']]

Resources:
  ResourceA:
    Properties:
      PropertyA: !If [toResolveSSMParam, !Sub '{{resolve:ssm:${anssmparameter}}}', !Ref placeholdervalue]

Upvotes: 1

Marcin
Marcin

Reputation: 238209

Sadly, you can't have conditions in Parameters, unless you write a tin wrapper around your deployment procedure which would modify the template before it goes to CloudFormation.

Other then that, you would have to use If conditions in Resources to actually alternate between different possibilities.

Upvotes: 1

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