Ruby script Net::SSH::HostKeyMismatch but ssh works - ruby

Question

I can ssh into a remote host on my aws network but using net/ssh fails in a ruby script. my gem is net-ssh(4.2.0) on Ubuntu 16.04. It doesn't prompt for a passphrase even with non_interactive => false.
error:
Authentication failed for user Net::SSH::AuthenticationFailed
Why does this code fail?
#!/usr/bin/env ruby
require 'rubygems'
require 'net/ssh'
HOST = 'myhost'
Net::SSH.start(HOST,
:auth_methods => ['publickey'],
:passphrase => 'mypassphrase',
:non_interactive => true,
:host_key => "ssh-rsa",
:keys => [ '/home/markhorrocks/.ssh/id_rsa' ]
) do |session|
output = session.exec!('ls')
puts output
end
After editing my code to this I get error
(Net::SSH::HostKeyMismatch)
HOST = 'myhost'
USER = 'markhorrocks'
Net::SSH.start(HOST, USER,
:auth_methods => ['publickey'],
:passphrase => 'mypassphrase',
:non_interactive => true,
:host_key => "ssh-rsa",
:encryption => "blowfish-cbc",
:keys => [ '/home/markhorrocks/.ssh/id_rsa' ],
:port => '1234',
:forward_agent => true,
:compression => "zlib#openssh.com"
) do |session|
output = session.exec!('ls')
puts output
end

Answer 1

The keys array needs to point at your private key(s). authorized_keys is the public fingerprints for keys allowed to log in to the current host. Also you seem to have put a private key type in for host_key.

Answer 2

Here is my solution:
#!/usr/bin/env ruby
require 'net/ssh'
HOST = 'myhost'
USER = 'markhorrocks'
Net::SSH.start(HOST, USER,
:auth_methods => ['publickey'],
:passphrase => 'mypassphrase',
:non_interactive => true,
:host_key => "ssh-rsa",
:encryption => "blowfish-cbc",
:keys => [ '/home/markhorrocks/.ssh/id_rsa' ],
:port => '1234',
:forward_agent => true,
:verify_host_key => false,
:compression => "zlib#openssh.com"
) do |session|
begin
rescue Net::SSH::HostKeyMismatch => e
puts "remembering new key: #{e.fingerprint}"
e.remember_host!
retry
end
output = session.exec!('ls')
puts output
end