deploy.rb

lock '3.7.2'

set :application, 'my application'
set :repo_url, 'somethingsomething.git'

set :ssh_options, proxy: Net::SSH::Proxy::Command.new("ssh -W %h:%p -q root@proxy_server} -i {private_key_for_proxy} -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no")

# All your other configs...
# Note: -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no
# This can be potentially unsafe on an unknown network but is helpful for
# unattended deployments.
#
# Use at your own risk.