Class: ElasticBeans::SSH

Inherits:
Object
  • Object
show all
Defined in:
lib/elastic_beans/ssh.rb

Overview

Opens an SSH connection, tunneling through a bastion host if specified.

Defined Under Namespace

Classes: BastionAuthenticationError, SSHFailedError

Instance Method Summary collapse

Constructor Details

#initialize(hostname:, username:, bastion_host: nil, bastion_username: nil, bastion_identity_file: nil, identity_file: nil, ssh_options: [], command: [], logger: Logger.new('/dev/null')) ⇒ SSH

Returns a new instance of SSH.



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# File 'lib/elastic_beans/ssh.rb', line 6

def initialize(
  hostname:,
  username:,
  bastion_host: nil,
  bastion_username: nil,
  bastion_identity_file: nil,
  identity_file: nil,
  ssh_options: [],
  command: [],
  logger: Logger.new('/dev/null')
)
  @hostname = hostname
  @username = username
  @bastion_host = bastion_host
  @bastion_username = bastion_username
  @bastion_identity_file = bastion_identity_file
  @identity_file = identity_file
  @ssh_options = ssh_options
  @command = command
  @logger = logger
end

Instance Method Details

#connect ⇒ Object

Opens an SSH connection, tunneling through a bastion host if specified. Spawns a child process using the ssh command-line utility and waits for it to complete.

Raises an error if SSH exits with a non-zero exit status.



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# File 'lib/elastic_beans/ssh.rb', line 32

def connect
  ssh_args = ["ssh", *ssh_options]

  if identity_file
    ssh_args << "-i"
    ssh_args << identity_file
  end

  gateway = nil
  if bastion_host
    ssh_args << "#{username}@localhost"
    ssh_args += ["-o", "UserKnownHostsFile=/dev/null", "-o", "StrictHostKeyChecking=no"]
    begin
      bastion_options = {auth_methods: ["publickey"]}
      if bastion_identity_file
        bastion_options[:key_data] = File.read(bastion_identity_file)
      end

      logger.info("Connecting to '#{bastion_username}@#{bastion_host}'...")
      gateway = Net::SSH::Gateway.new(
        bastion_host,
        bastion_username,
        bastion_options,
      )
      port = gateway.open(hostname, 22)
      logger.debug { "Opened gateway to '#{hostname}' on port '#{port}'" }
      ssh_args += ["-p", port.to_s]
    rescue Net::SSH::Exception => e
      raise BastionAuthenticationError.new(cause: e)
    end
  else
    ssh_args << "#{username}@#{hostname}"
  end

  logger.debug { "Connecting: `#{ssh_args.join(' ')}'..." }
  pid = Process.spawn(*ssh_args, *command)
  _, status = Process.waitpid2(pid)
  unless status.success?
    raise SSHFailedError
  end
ensure
  gateway.close(port) if gateway
end