Drop Net::SSH::Gateway dependency

[kke]

The Net::SSH::Gateway class is rather simple, but still a bit inflexible.

For example, it does not allow reusing an existing connection and a new one will be always opened for each gateway.

Port forwarding on Net::SSH is quite simple:

"Um, all I want to do is X, just show me how!"

X == "forward connections on a local port to a remote host"

Net::SSH.start("host", "user", :password => "password") do |ssh|
  ssh.forward.local(1234, "www.google.com", 80)
  ssh.loop { true }
end

The IOError rescue retries are there to make it automatically reconnect both self + tunnel in case the tunnel has died. (The current connection does not know if the underlying tunnel has disconnected until it tries to send / receive)

This on its own doesn't fix anything (because it's missing all the host/bastion dereferencing et all), but having this could simplify #1090 and #1003

[jakolehm]

Looks pretty good 👍 E2e still shows some errors/backtraces.

[kke]

I think the exception is different on Linux vs mac.

I get these with DEBUG_TRANSPORT=true

D, [2019-03-15T15:19:32.414816 #43061] DEBUG -- Pharos::Transport::SSH[192.168.100.101]: Received Errno::EBADF (expected when tunnel has been closed)
D, [2019-03-15T15:19:32.414916 #43061] DEBUG -- Pharos::Transport::SSH[192.168.100.101]: Closed SSH event loop
D, [2019-03-15T15:19:32.414874 #43061] DEBUG -- Pharos::Transport::SSH[192.168.100.101]: Closed port forward on 65534
D, [2019-03-15T15:19:32.415257 #43061] DEBUG -- Pharos::Transport::SSH[192.168.100.102]: Received Errno::EBADF (expected when tunnel has been closed)
D, [2019-03-15T15:19:32.415334 #43061] DEBUG -- Pharos::Transport::SSH[192.168.100.102]: Closed SSH event loop
D, [2019-03-15T15:19:32.415294 #43061] DEBUG -- Pharos::Transport::SSH[192.168.100.102]: Closed port forward on 65533

Added IOError to the rescue and the exceptions seem to be gone from e2e output now.

[jakolehm]

LGTM