Comment 6 for bug 1883242

Nobuto, Billy suggested we consider switching to Vault's integrated storage to simplify things and reduce dependencies even further:

> I'm wondering if we should actually support etcd as a backend, or just go straight to the raft based integrated storage provided with Vault in newer versions (see [1] and [2]). This would further remove additional requirements of applications.

> The move to integrated storage doesn't necessarily remove the need to support different backends in a flexible way - but may not run into some of the various tangles involved with the current interfaces without running into awkwardness in the migration paths, etc.

> [1] - https://www.vaultproject.io/docs/internals/integrated-storage
> [2] - https://www.vaultproject.io/docs/configuration/storage/raft

What are your thoughts on this?

I can see two potential challenges:

1. requires vault to be a new enough version to support it. Not sure how it works with charms and enforcing software versions, or how this would work with updating the charm.

2. potentially breaks backwards compatibility with the charm.