Class: RemoteSystem

Inherits:
System show all
Defined in:
lib/remote_system.rb

Overview

Copyright © 2013-2015 SUSE LLC

This program is free software; you can redistribute it and/or modify it under the terms of version 3 of the GNU General Public License as published by the Free Software Foundation.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, contact SUSE LLC.

To contact SUSE about this file by physical or electronic mail, you may find current contact information at www.suse.com

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from System

#check_requirement, #create_archive, for, #has_command?, #run_script

Constructor Details

#initialize(host, remote_user = "root") ⇒ RemoteSystem

Returns a new instance of RemoteSystem.



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# File 'lib/remote_system.rb', line 22

def initialize(host, remote_user = "root")
  @host = host
  @remote_user = remote_user

  connect
end

Instance Attribute Details

#host ⇒ Object

Returns the value of attribute host.



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# File 'lib/remote_system.rb', line 19

def host
  @host
end

#remote_user ⇒ Object

Returns the value of attribute remote_user.



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# File 'lib/remote_system.rb', line 20

def remote_user
  @remote_user
end

Instance Method Details

#connect ⇒ Object

Tries to run the noop-command(:) on the remote system as root (without a password or passphrase) and raises an Machinery::Errors::SshConnectionFailed exception when it’s not successful.



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# File 'lib/remote_system.rb', line 88

def connect
  LoggedCheetah.run "ssh", "-q", "-o", "BatchMode=yes", "#{remote_user}@#{host}", ":"
rescue Cheetah::ExecutionFailed
  raise Machinery::Errors::SshConnectionFailed.new(
    "Could not establish SSH connection to host '#{host}'. Please make sure that " \
    "you can connect non-interactively as #{remote_user}, e.g. using ssh-agent.\n\n" \
    "To copy your default ssh key to the machine run:\n" \
    "ssh-copy-id #{remote_user}@#{host}"
  )
end

#read_file(file) ⇒ Object

Reads a file from the System. Returns nil if it does not exist.



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# File 'lib/remote_system.rb', line 133

def read_file(file)
  run_command("cat", file, stdout: :capture, privileged: true)
rescue Cheetah::ExecutionFailed => e
  if e.status.exitstatus == 1
    # File not found, return nil
    return
  else
    raise
  end
end

#requires_root? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/remote_system.rb', line 29

def requires_root?
  false
end

#retrieve_files(filelist, destination) ⇒ Object

Retrieves files specified in filelist from the remote system and raises an Machinery::Errors::RsyncFailed exception when it’s not successful. Destination is the directory where to put the files.



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# File 'lib/remote_system.rb', line 103

def retrieve_files(filelist, destination)
  source = "#{remote_user}@#{host}:/"
  if remote_user != "root"
    rsync_path = "sudo -n rsync"
  else
    rsync_path = "rsync"
  end

  cmd = [
    "rsync",
    "-e", "ssh",
    "--chmod=go-rwx",
    "--files-from=-",
    "--rsync-path=#{rsync_path}",
    source,
    destination,
    stdout: :capture,
    stdin: filelist.join("\n")
  ]
  begin
    LoggedCheetah.run(*cmd)
  rescue Cheetah::ExecutionFailed  => e
    raise Machinery::Errors::RsyncFailed.new(
    "Could not rsync files from host '#{host}'.\n" \
    "Error: #{e}"
  )
  end
end

#run_command(*args) ⇒ Object 



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# File 'lib/remote_system.rb', line 33

def run_command(*args)
  options = args.last.is_a?(Hash) ? args.pop : {}

  # There are three valid ways how to call Cheetah.run, whose interface this
  # method mimics. The following code ensures that the "commands" variable
  # consistently (in all three cases) contains an array of arrays specifying
  # commands and their arguments.
  #
  # See comment in Cheetah.build_commands for more detailed explanation:
  #
  #   https://github.com/openSUSE/cheetah/blob/0cd3f88c1210305e87dfc4852bb83040e82d783f/lib/cheetah.rb#L395
  #
  commands = args.all? { |a| a.is_a?(Array) } ? args : [args]

  # When ssh executes commands, it passes them through shell expansion. For
  # example, compare
  #
  #   $ echo '$HOME'
  #   $HOME
  #
  # with
  #
  #   $ ssh localhost echo '$HOME'
  #   /home/dmajda
  #
  # To mitigate that and maintain usual Cheetah semantics, we need to protect
  # the command and its arguments using another layer of escaping.
  escaped_commands = commands.map do |command|
    command.map { |c| Shellwords.escape(c) }
  end

  # Arrange the commands in a way that allows piped commands trough ssh.
  piped_args = escaped_commands[0..-2].flat_map do |command|
    [*command, "|"]
  end + escaped_commands.last

  if options[:disable_logging]
    cheetah_class = Cheetah
  else
    cheetah_class = LoggedCheetah
  end

  sudo = ["sudo", "-n"] if options[:privileged] && remote_user != "root"
  cmds = ["ssh", "#{remote_user}@#{host}", sudo, "LC_ALL=C", *piped_args, options].compact.flatten
  cheetah_class.run(*cmds)
rescue Cheetah::ExecutionFailed => e
  if e.stderr.include?("password is required")
    raise Machinery::Errors::InsufficientPrivileges.new(remote_user, host)
  else
    raise e
  end
end