Default value on mappings AWS CloudFormation

Question

What would be a good strategy to have a default value on mappings?

I.E.

I have a parameter called country

Based on that country I reference a DNS using mappings

"Mappings" : {
   "DNS":{
     "us" : {"dns" : "mypage.us.com", "ttl" : "600"},
     "mx" : {"dns" : "mypage.default.com", "ttl" : "300"},
     "ar" : {"dns" : "mypage.default.com", "ttl" : "300"},
     "br" : {"dns" : "mypage.default.com", "ttl" : "300"}
   }
}

If us it's been mapped:

{ "Fn::FindInMap" : [ "DNS", { "Ref" : "country" }, "dns" ]}

I get "mypage.us.com" for the other countries I've created a huge list of countries with a default value mypage.default.com, in the future, this values will be changing and we will be adding more countries, is there a better approach to this?

Answer 1

The only way I was able to do this was to chain Fn::If statements instead of using the map. I tried using a combination of Fn::If and Fn::FindInMap but Fn::FindInMap will always raise an error it if can't find the mapping.

Therefore the only solution for me was to resort to using something like the following (for me it was setting ecs memory based on instance type):

Conditions:
  IsT2Micro: !Equals [!Ref InstanceType, "t2.micro"]
  IsT2Small: !Equals [!Ref InstanceType, "t2.small"]
  ...

taskdefinition:
    Type: AWS::ECS::TaskDefinition
    Properties:
      ...
      Memory: !If [ IsT2Micro, 900, !If [ IsT2Small, 1900, !Ref "AWS::NoValue"]]