What's a similarly easy alternative to Boot2Docker, where I can just have Rancher install the VM for me instead of handcrafting a VM template? With Boot2Docker, I'm getting

Get <https://nexus.company.tld:8444/v2/>: x509: certificate has expired or is not yet valid

when trying to access anything with letsencrypt certs, probably because Boot2Docker was last updated before letsencrypt switched certs.