Exception when my ssh keyring contains an ed25519 key

[thommay]

Description

When my ssh agent contains an ed25519 key, trying to connect to a host results in an exception being raise.

Chef Workstation Version

14:05 ~/work/chef % chef-run -v 
chef-run: 0.1.124

Platform Version

macOS 10.13

Replication Case

14:04 ~/work/chef % ssh-add -l
2048 SHA256:xxxxxx /Users/thom/.ssh/id_rsa (RSA)
256 SHA256:xxxx thom@UNKNOWN (ED25519)

chef-run ec2-xxx.eu-west-1.compute.amazonaws.com --user ubuntu apt_update foo action=run

Client Output

[-] [ec2-xxx.eu-west-1.compute.amazonaws.com] Connecting...
INTERNAL ERROR
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Message:
unsupported key type `ssh-ed25519'
net-ssh requires the following gems for ed25519 support:
 * rbnacl (>= 3.2, < 5.0)
 * rbnacl-libsodium, if your system doesn't have libsodium installed.
 * bcrypt_pbkdf (>= 1.0, < 2.0)
See https://github.com/net-ssh/net-ssh/issues/478 for more information
Gem::MissingSpecError : "Could not find 'rbnacl' (< 5.0, >= 3.2.0) among 324 total gem(s)

[cheeseplus]

Closing as dupe of #231 - this issue is older but #231 is more generically "we should support these".