Using CoreOS and securing the different components requires TLS.
There's etcd, docker, and other services that need CA to sign certs. Is it OK to use the same CA cert to sign the different certs for all the services, or should I really create a CA for each service?
I know this is subjective and I may get lots of 'opinions', but is there really any good reason to create several CAs?
Do not create a CA for each service. The idea is to have one single CA, whose CA cert is imported into each of your systems' trusted CA list. That way, you can sign all of your certs using that CA and they will be trusted.