I am running Docker on my ubuntu laptop. This is just the development environment. Once all the bugs are run down I will move it to my Lightsail environment on AWS. As part of my "due dilligence" I need to make sure that I am securing user's data. Thus I plan to use AWS Secret Manager. To do this I am required to set up https with TLS on my ubuntu laptop (which is running Docker).
I was told by a Docker expert I use sometimes that setting up a cert on a Docker PC is "impossible". Is this true? Can a LE cert be used?
As long as you have a fully-qualified (sub)domain name with a public DNS, at the very least it is always possible to get a certificate issued by using dns-01 challenges (adding TXT records to your DNS) to prove your control of the (sub)domain name. Thus, as long as your server is reachable (by you) using that (sub)domain name and has the issued certificate installed, I don't forsee any issues.
We've had many people visit who have successfully acquired and utilized certificates using Docker.