Class: Train::Transports::SSH::Connection

Inherits:
BaseConnection
  • Object
show all
Defined in:
lib/train/transports/ssh_connection.rb

Overview

A Connection instance can be generated and re-generated, given new connection details such as connection port, hostname, credentials, etc. This object is responsible for carrying out the actions on the remote host such as executing commands, transferring files, etc.

Author:

Constant Summary collapse

GNU_TIMEOUT_EXIT_STATUS =

If we use the GNU timeout utility to timout a command server-side, it will exit with this status code if the command timed out.

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Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options) ⇒ Connection

Returns a new instance of Connection.



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# File 'lib/train/transports/ssh_connection.rb', line 39

def initialize(options)
  # Track IOS command retries to prevent infinite loop on IOError. This must
  # be done before `super()` because the parent runs detection commands.
  @ios_cmd_retries = 0

  super(options)

  @session                = nil
  @username               = @options.delete(:username)
  @hostname               = @options.delete(:hostname)
  @port                   = @options[:port] # don't delete from options
  @connection_retries     = @options.delete(:connection_retries)
  @connection_retry_sleep = @options.delete(:connection_retry_sleep)
  @max_wait_until_ready   = @options.delete(:max_wait_until_ready)
  @max_ssh_sessions       = @options.delete(:max_ssh_connections) { 9 }
  @transport_options      = @options.delete(:transport_options)
  @proxy_command          = @options.delete(:proxy_command)
  @bastion_host           = @options.delete(:bastion_host)
  @bastion_user           = @options.delete(:bastion_user)
  @bastion_port           = @options.delete(:bastion_port)

  @cmd_wrapper = CommandWrapper.load(self, @transport_options)
end

Instance Attribute Details

#hostname ⇒ Object (readonly)

rubocop:disable Metrics/ClassLength



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# File 'lib/train/transports/ssh_connection.rb', line 32

def hostname
  @hostname
end

#transport_options ⇒ Object

Returns the value of attribute transport_options.



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# File 'lib/train/transports/ssh_connection.rb', line 33

def transport_options
  @transport_options
end

Instance Method Details

#check_proxy ⇒ Object 



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# File 'lib/train/transports/ssh_connection.rb', line 94

def check_proxy
  [@proxy_command, @bastion_host].any? { |type| !type.nil? }
end

#close ⇒ Object 



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# File 'lib/train/transports/ssh_connection.rb', line 64

def close
  return if @session.nil?

  logger.debug("[SSH] closing connection to #{self}")
  session.close
ensure
  @session = nil
end

#download(remotes, local) ⇒ Object 



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# File 'lib/train/transports/ssh_connection.rb', line 134

def download(remotes, local)
  waits = []
  Array(remotes).map do |remote|
    opts = file(remote).directory? ? { recursive: true } : {}
    waits.push session.scp.download(remote, local, opts) do |_ch, name, recv, total|
      logger.debug("Downloaded #{name} (#{total} bytes)") if recv == total
    end
    waits.shift.wait while waits.length >= @max_ssh_sessions
  end
  waits.each(&:wait)
rescue Net::SSH::Exception => ex
  raise Train::Transports::SSHFailed, "SCP download failed (#{ex.message})"
end

#forward_remote(port, host, remote_port, remote_host = "127.0.0.1") ⇒ Object

remote_port_forwarding



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# File 'lib/train/transports/ssh_connection.rb', line 165

def forward_remote(port, host, remote_port, remote_host = "127.0.0.1")
  @session.forward.remote(port, host, remote_port, remote_host)
end

#generate_proxy_command ⇒ Object 



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# File 'lib/train/transports/ssh_connection.rb', line 98

def generate_proxy_command
  return @proxy_command unless @proxy_command.nil?

  args = %w{ ssh }
  args += ssh_opts
  args += %W{ #{@bastion_user}@#{@bastion_host} }
  args += %W{ -p #{@bastion_port} }
  args += %w{ -W %h:%p }
  args.join(" ")
end

#login_command ⇒ Object 



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# File 'lib/train/transports/ssh_connection.rb', line 110

def 
  args = ssh_opts
  args += %W{ -o ProxyCommand='#{generate_proxy_command}' } if check_proxy
  args += %W{ -p #{@port} }
  args += %W{ #{@username}@#{@hostname} }
  LoginCommand.new("ssh", args)
end

#obscured_options ⇒ Object 



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# File 'lib/train/transports/ssh_connection.rb', line 169

def obscured_options
  options_to_print = @options.clone
  options_to_print[:password] = "<hidden>" if options_to_print.key?(:password)
  options_to_print
end

#ssh_opts ⇒ Object 



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# File 'lib/train/transports/ssh_connection.rb', line 73

def ssh_opts
  level = logger.debug? ? "VERBOSE" : "ERROR"
  fwd_agent = options[:forward_agent] ? "yes" : "no"

  args  = %w{ -o UserKnownHostsFile=/dev/null }
  args += %w{ -o StrictHostKeyChecking=no }
  args += %w{ -o BatchMode=yes } if options[:non_interactive]
  args += %W{ -o LogLevel=#{level} }
  args += %W{ -o ForwardAgent=#{fwd_agent} } if options.key?(:forward_agent)

  keys = Array(options[:keys])
  unless keys.empty?
    args += %w{ -o IdentitiesOnly=yes }
    keys.each do |ssh_key|
      args += %W{ -i #{ssh_key} }
    end
  end

  args
end

#upload(locals, remote) ⇒ Object 



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# File 'lib/train/transports/ssh_connection.rb', line 119

def upload(locals, remote)
  waits = []
  Array(locals).each do |local|
    opts = File.directory?(local) ? { recursive: true } : {}

    waits.push session.scp.upload(local, remote, opts) do |_ch, name, sent, total|
      logger.debug("Uploaded #{name} (#{total} bytes)") if sent == total
    end
    waits.shift.wait while waits.length >= @max_ssh_sessions
  end
  waits.each(&:wait)
rescue Net::SSH::Exception => ex
  raise Train::Transports::SSHFailed, "SCP upload failed (#{ex.message})"
end

#uri ⇒ Object 



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# File 'lib/train/transports/ssh_connection.rb', line 160

def uri
  "ssh://#{@username}@#{@hostname}:#{@port}"
end

#wait_until_ready ⇒ Object 



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# File 'lib/train/transports/ssh_connection.rb', line 149

def wait_until_ready
  delay = 3
  session(
    retries: @max_wait_until_ready / delay,
    delay:   delay,
    message: "Waiting for SSH service on #{@hostname}:#{@port}, " \
             "retrying in #{delay} seconds"
  )
  run_command(PING_COMMAND.dup)
end

#with_sudo_pty ⇒ Object 



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# File 'lib/train/transports/ssh_connection.rb', line 175

def with_sudo_pty
  old_pty = transport_options[:pty]
  transport_options[:pty] = true if @sudo

  yield
ensure
  transport_options[:pty] = old_pty
end