Should Vault use systemd's new credentials facility?

[c0c0n3]

We could reimplement our vault to serve secrets over a Unix socket connected to systemd's new credentials facility. This way we won't need to ever store unencrypted data on a filesystem, not even a RAM-backed one.

See:

• https://systemd.io/CREDENTIALS/
• https://medium.com/@umglurf/using-systemd-credentials-to-pass-secrets-from-hashicorp-vault-to-systemd-services-928f0e804518