Today is yet short one, but ideally will already save a whole lot of headaches for some people.
Scenario: You have stored the contents of a string using AWS SSM parameter store (side note: if you are not using it yet, you should definitely have a look), but when retrieving it decrypted via CLI, you notice that the string has new lines ('\n') substituted by spaces (' ').
In my case, I was storing a private SSH key encrypted to integrate with some Ansible scripts triggered via AWS CodePipeline + CodeBuild. CodeBuild makes it realy easy to access secrets stored in SSM store, however it was retrieving my key incorrectly, which in term domino-crashed my ansible scripts.
Here you can also confirm more people are facing this issue. After following the suggestion of using AWS SDK - in my case with python boto3 - it finally worked. So here is a gist to overwrite an AWS SSM parameter, and then retrieving it back:
Hope this helps!