This adds a new mechanism for worker authentication that uses the
third-party arbitration of the original KMS flow by leveraging
recently-added capabilities in nodeenrollment to support a registration
wrapper. This allows for workers to be registered to the system with
just a name and a matching wrapper, while at the same time allowing
these workers to be used for private Vault access and multi-hop as they
contain per-worker encryption keys and support rotation.
Nodes using this mode will generate and rotate credentials in-memory
(using another recently added nodeenrollment capability) so will have a
new set of keys on every startup. This has the side effect of ensuring
that there is never a conflict or re-use of these credentials.
Note that the normal test worker flow was using the now-deprecated KMS
method; there is still a test that uses this (explicitly) but all other
tests using test workers that did not specify a specific PKI flow now
actually use this mechanism. This means there is fairly decent test
coverage in a general sense, plus the specific tests updated/added for
this feature.
This also adds a new KMS type that can be used to have
distinct KMSes for upstream authentication vs. accepting from
downstream.
Jeff Mitchell
163ce184b8