This tool will print out a signature and nonce to be used with vault-plugin-auth-ssh
Need createsig <key-path> <password>
eg. createsig id_rsa mypassword
If you don't have a password just omit it
eg. createsig id_rsa
Use go get, resulting binary will be in ~/go/bin/createsig
go get github.com/42wim/vault-plugin-auth-ssh/createsig