I have created a domain name certificate in ACM and optioned for DNS validation, and now I have a list of CNAME records on my ACM page, that I need to create in my domain settings, to allow SSL for my domain.
Is it secure if I add those CNAME records through Cloudformation that is connected to git? It is more convenient and maintainable than doing it by hands, but I am afraid about security.
I don't think there is any security concerns of having DNS validation in a cloud formation template in github.
Keep passwords and access keys and the like out of github. But there is none of that type of data in the resources you describe.