Class: Bolt::Shell::Bash

Inherits:
Bolt::Shell show all
Defined in:
lib/bolt/shell/bash.rb,
lib/bolt/shell/bash/tmpdir.rb

Defined Under Namespace

Classes: Tmpdir

Constant Summary collapse

CHUNK_SIZE = 
4096

Instance Attribute Summary

Attributes inherited from Bolt::Shell

#conn, #logger, #target

Instance Method Summary collapse

Methods inherited from Bolt::Shell

#default_input_method, #envify_params, #select_implementation, #select_interpreter, #unwrap_sensitive_args

Constructor Details

#initialize(target, conn) ⇒ Bash

Returns a new instance of Bash.



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# File 'lib/bolt/shell/bash.rb', line 11

def initialize(target, conn)
  super

  @run_as = nil
  @sudo_id = SecureRandom.uuid
  @sudo_password = @target.options['sudo-password'] || @target.password
end

Instance Method Details

#check_sudo(out, inp, stdin) ⇒ Object

See if there’s a sudo prompt in the output If not, return the output



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# File 'lib/bolt/shell/bash.rb', line 220

def check_sudo(out, inp, stdin)
  buffer = out.readpartial(CHUNK_SIZE)
  # Split on newlines, including the newline
  lines = buffer.split(/(?<=\n)/)
  # handle_sudo will return the line if it is not a sudo prompt or error
  lines.map! { |line| handle_sudo(inp, line, stdin) }
  lines.join
# If stream has reached EOF, no password prompt is expected
# return an empty string
rescue EOFError
  ''
end

#download(source, destination, options = {}) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 52

def download(source, destination, options = {})
  running_as(options[:run_as]) do
    download = File.join(destination, Bolt::Util.unix_basename(source))

    # If using run-as, the file is copied to a tmpdir and chowned to the
    # connecting user. This is a workaround for limitations in net-ssh that
    # only allow for downloading files as the connecting user, which is a
    # problem for users who cannot connect to targets as the root user.
    # This temporary copy should *always* be deleted.
    if run_as
      with_tmpdir(force_cleanup: true) do |dir|
        tmpfile = File.join(dir.to_s, Bolt::Util.unix_basename(source))

        result = execute(['cp', '-r', source, dir.to_s], sudoable: true)

        if result.exit_code != 0
          message = "Could not copy file '#{source}' to temporary directory '#{dir}': #{result.stderr.string}"
          raise Bolt::Node::FileError.new(message, 'CP_ERROR')
        end

        # We need to force the chown, otherwise this will just return
        # without doing anything since the chown user is the same as the
        # connecting user.
        dir.chown(conn.user, force: true)

        conn.download_file(tmpfile, destination, download)
      end
    # If not using run-as, we can skip creating a temporary copy and just
    # download the file directly.
    else
      conn.download_file(source, destination, download)
    end

    Bolt::Result.for_download(target, source, destination, download)
  end
end

#execute(command, sudoable: false, **options) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 344

def execute(command, sudoable: false, **options)
  run_as = options[:run_as] || self.run_as
  escalate = sudoable && run_as && conn.user != run_as
  use_sudo = escalate && @target.options['run-as-command'].nil?

  # Depending on the transport, whether we're using sudo and whether
  # there are environment variables to set, we may need to stitch
  # together multiple commands into a single sh invocation
  commands = [inject_interpreter(options[:interpreter], command)]

  # Let the transport handle adding environment variables if it's custom.
  if options[:environment]
    if defined? conn.add_env_vars
      conn.add_env_vars(options[:environment])
    else
      env_decl = '/usr/bin/env ' + options[:environment].map do |env, val|
        "#{env}=#{Shellwords.shellescape(val)}"
      end.join(' ')
    end
  end

  if escalate
    sudo_str = if use_sudo
                 sudo_exec = target.options['sudo-executable'] || "sudo"
                 sudo_flags = [sudo_exec, "-S", "-H", "-u", run_as, "-p", sudo_prompt]
                 Shellwords.shelljoin(sudo_flags)
               else
                 Shellwords.shelljoin(@target.options['run-as-command'] + [run_as])
               end
    commands.unshift('cd') if conn.reset_cwd?
    commands.unshift(sudo_success(@sudo_id)) if options[:stdin] && !options[:wrapper]
  end

  command_str = if sudo_str || env_decl
                  "sh -c #{Shellwords.shellescape(commands.join('; '))}"
                else
                  commands.last
                end

  command_str = [sudo_str, env_decl, command_str].compact.join(' ')

  @logger.trace { "Executing `#{command_str}`" }

  in_buffer = if !use_sudo && options[:stdin]
                String.new(options[:stdin], encoding: 'binary')
              else
                String.new(encoding: 'binary')
              end
  # Chunks of this size will be read in one iteration
  index = 0
  timeout = 0.1
  result_output = Bolt::Node::Output.new

  inp, out, err, t = conn.execute(command_str)
  read_streams = { out => String.new,
                   err => String.new }
  write_stream = in_buffer.empty? ? [] : [inp]

  # See if there's a sudo prompt
  if use_sudo
    ready_read = select([err], nil, nil, timeout * 5)
    to_print = check_sudo(err, inp, options[:stdin]) if ready_read
    unless to_print.nil?
      log_stream(to_print, 'err')
      read_streams[err]           << to_print
      result_output.merged_output << to_print
    end
  end

  # True while the process is running or waiting for IO input
  while t.alive?
    # See if we can read from out or err, or write to in
    ready_read, ready_write, = select(read_streams.keys, write_stream, nil, timeout)

    ready_read&.each do |stream|
      stream_name = stream == out ? 'out' : 'err'
      # Check for sudo prompt
      to_print = if use_sudo
                   check_sudo(stream, inp, options[:stdin])
                 else
                   stream.readpartial(CHUNK_SIZE)
                 end
      log_stream(to_print, stream_name)
      read_streams[stream]        << to_print
      result_output.merged_output << to_print
    rescue EOFError
    end

    # select will either return an empty array if there are no
    # writable streams or nil if no IO object is available before the
    # timeout is reached.
    writable = if ready_write.respond_to?(:empty?)
                 !ready_write.empty?
               else
                 !ready_write.nil?
               end

    begin
      if writable && index < in_buffer.length
        to_print = in_buffer[index..-1]
        # On Windows, select marks the input stream as writable even if
        # it's full. We need to check whether we received wait_writable
        # and treat that as not having written anything.
        written = inp.write_nonblock(to_print, exception: false)
        index += written unless written == :wait_writable

        if index >= in_buffer.length && !write_stream.empty?
          inp.close
          write_stream = []
        end
      end
    # If a task has stdin as an input_method but doesn't actually read
    # from stdin, the task may return and close the input stream before
    # we finish writing
    rescue Errno::EPIPE
      write_stream = []
    end
  end
  # Read any remaining data in the pipe. Do not wait for
  # EOF in case the pipe is inherited by a child process.
  read_streams.each do |stream, _|
    stream_name = stream == out ? 'out' : 'err'
    loop {
      to_print = stream.read_nonblock(CHUNK_SIZE)
      log_stream(to_print, stream_name)
      read_streams[stream]        << to_print
      result_output.merged_output << to_print
    }
  rescue Errno::EAGAIN, EOFError
  ensure
    stream.close
  end
  inp.close
  result_output.stdout << read_streams[out]
  result_output.stderr << read_streams[err]
  result_output.exit_code = t.value.respond_to?(:exitstatus) ? t.value.exitstatus : t.value

  case result_output.exit_code
  when 0
    @logger.trace { "Command `#{command_str}` returned successfully" }
  when 126
    msg = "\n\nThis might be caused by the default tmpdir being mounted "\
      "using 'noexec'. See http://pup.pt/task-failure for details and workarounds."
    result_output.stderr        << msg
    result_output.merged_output << msg
    @logger.trace { "Command #{command_str} failed with exit code #{result_output.exit_code}" }
  else
    @logger.trace { "Command #{command_str} failed with exit code #{result_output.exit_code}" }
  end
  result_output
rescue StandardError
  # Ensure we close stdin and kill the child process
  inp.close unless inp.nil? || inp.closed?
  t&.terminate if t&.alive?
  @logger.trace { "Command aborted" }
  raise
end

#handle_sudo(stdin, err, sudo_stdin) ⇒ Object

If prompted for sudo password, send password to stdin and return an empty string. Otherwise, check for sudo errors and raise Bolt error. If sudo_id is detected, that means the task needs to have stdin written. If error is not sudo-related, return the stderr string to be added to node output



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# File 'lib/bolt/shell/bash.rb', line 189

def handle_sudo(stdin, err, sudo_stdin)
  if err.include?(sudo_prompt)
    # A wild sudo prompt has appeared!
    if @sudo_password
      stdin.write("#{@sudo_password}\n")
      ''
    else
      raise Bolt::Node::EscalateError.new(
        "Sudo password for user #{conn.user} was not provided for #{target}",
        'NO_PASSWORD'
      )
    end
  elsif err =~ /^#{@sudo_id}/
    if sudo_stdin
      begin
        stdin.write("#{sudo_stdin}\n")
        stdin.close
      # If a task has stdin as an input_method but doesn't actually read
      # from stdin, the task may return and close the input stream before
      # we finish writing
      rescue Errno::EPIPE
      end
    end
    ''
  else
    handle_sudo_errors(err)
  end
end

#handle_sudo_errors(err) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 233

def handle_sudo_errors(err)
  case err
  when /^#{conn.user} is not in the sudoers file\./
    @logger.trace { err }
    raise Bolt::Node::EscalateError.new(
      "User #{conn.user} does not have sudo permission on #{target}",
      'SUDO_DENIED'
    )
  when /^Sorry, try again\./
    @logger.trace { err }
    raise Bolt::Node::EscalateError.new(
      "Sudo password for user #{conn.user} not recognized on #{target}",
      'BAD_PASSWORD'
    )
  else
    # No need to raise an error - just return the string
    err
  end
end

#inject_interpreter(interpreter, command) ⇒ Object

Returns string with the interpreter conditionally prepended



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# File 'lib/bolt/shell/bash.rb', line 336

def inject_interpreter(interpreter, command)
  if interpreter
    command = Array(command).unshift(interpreter).flatten
  end

  command.is_a?(String) ? command : Shellwords.shelljoin(command)
end

#make_executable(path) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 286

def make_executable(path)
  result = execute(['chmod', 'u+x', path])
  if result.exit_code != 0
    message = "Could not make file '#{path}' executable: #{result.stderr.string}"
    raise Bolt::Node::FileError.new(message, 'CHMOD_ERROR')
  end
end

#make_tmpdir ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 294

def make_tmpdir
  tmpdir = @target.options.fetch('tmpdir', '/tmp')
  script_dir = @target.options.fetch('script-dir', SecureRandom.uuid)
  tmppath = File.join(tmpdir, script_dir)
  command = ['mkdir', '-m', 700, tmppath]

  result = execute(command)
  if result.exit_code != 0
    raise Bolt::Node::FileError.new("Could not make tmpdir: #{result.stderr.string}", 'TMPDIR_ERROR')
  end
  path = tmppath || result.stdout.string.chomp
  Bolt::Shell::Bash::Tmpdir.new(self, path)
end

#make_wrapper_stringio(task_path, stdin, interpreter = nil) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 253

def make_wrapper_stringio(task_path, stdin, interpreter = nil)
  if interpreter
    StringIO.new(<<~SCRIPT)
      #!/bin/sh
      #{Array(interpreter).map { |word| "'#{word}'" }.join(' ')} '#{task_path}' <<'EOF'
      #{stdin}
      EOF
    SCRIPT
  else
    StringIO.new(<<~SCRIPT)
      #!/bin/sh
      '#{task_path}' <<'EOF'
      #{stdin}
      EOF
    SCRIPT
  end
end

#provided_features ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 19

def provided_features
  ['shell']
end

#run_as ⇒ Object

This method allows the @run_as variable to be used as a per-operation override for the user to run as. When @run_as is unset, the user specified on the target will be used.



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# File 'lib/bolt/shell/bash.rb', line 274

def run_as
  @run_as || target.options['run-as']
end

#run_command(command, options = {}, position = []) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 23

def run_command(command, options = {}, position = [])
  running_as(options[:run_as]) do
    output = execute(command, environment: options[:env_vars], sudoable: true)
    Bolt::Result.for_command(target,
                             output.to_h,
                             'command',
                             command,
                             position)
  end
end

#run_script(script, arguments, options = {}, position = []) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 89

def run_script(script, arguments, options = {}, position = [])
  # unpack any Sensitive data
  arguments = unwrap_sensitive_args(arguments)

  running_as(options[:run_as]) do
    with_tmpdir do |dir|
      path = write_executable(dir.to_s, script)
      dir.chown(run_as)

      exec_args   = [path, *arguments]
      interpreter = select_interpreter(script, target.options['interpreters'])

      # Only use interpreter if script_interpreter config is enabled
      if options[:script_interpreter] && interpreter
        exec_args.unshift(interpreter).flatten!
        logger.trace("Running '#{script}' using '#{interpreter}' interpreter")
      end

      output = execute(exec_args, environment: options[:env_vars], sudoable: true)
      Bolt::Result.for_command(target,
                               output.to_h,
                               'script',
                               script,
                               position)
    end
  end
end

#run_task(task, arguments, options = {}, position = []) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 117

def run_task(task, arguments, options = {}, position = [])
  implementation = select_implementation(target, task)
  executable = implementation['path']
  input_method = implementation['input_method']
  extra_files = implementation['files']

  running_as(options[:run_as]) do
    stdin, output = nil
    execute_options = {}
    execute_options[:interpreter] = select_interpreter(executable, target.options['interpreters'])
    interpreter_debug = if execute_options[:interpreter]
                          " using '#{execute_options[:interpreter]}' interpreter"
                        end
    # log the arguments with sensitive data redacted, do NOT log unwrapped_arguments
    logger.trace("Running '#{executable}' with #{arguments.to_json}#{interpreter_debug}")
    # unpack any Sensitive data
    arguments = unwrap_sensitive_args(arguments)

    with_tmpdir do |dir|
      if extra_files.empty?
        task_dir = dir
      else
        # TODO: optimize upload of directories
        arguments['_installdir'] = dir.to_s
        task_dir = File.join(dir.to_s, task.tasks_dir)
        dir.mkdirs([task.tasks_dir] + extra_files.map { |file| File.dirname(file['name']) })
        extra_files.each do |file|
          conn.upload_file(file['path'], File.join(dir.to_s, file['name']))
        end
      end

      if Bolt::Task::STDIN_METHODS.include?(input_method)
        stdin = JSON.dump(arguments)
      end

      if Bolt::Task::ENVIRONMENT_METHODS.include?(input_method)
        execute_options[:environment] = envify_params(arguments)
      end

      remote_task_path = write_executable(task_dir, executable)

      execute_options[:stdin] = stdin

      # Avoid the horrors of passing data on stdin via a tty on multiple platforms
      # by writing a wrapper script that directs stdin to the task.
      if stdin && target.options['tty']
        wrapper = make_wrapper_stringio(remote_task_path, stdin, execute_options[:interpreter])
        # Wrapper script handles interpreter and stdin. Delete these execute options
        execute_options.delete(:interpreter)
        execute_options.delete(:stdin)
        execute_options[:wrapper] = true
        remote_task_path = write_executable(dir, wrapper, 'wrapper.sh')
      end

      dir.chown(run_as)

      execute_options[:sudoable] = true if run_as
      output = execute(remote_task_path, **execute_options)
    end
    Bolt::Result.for_task(target, output.stdout.string,
                          output.stderr.string,
                          output.exit_code,
                          task.name,
                          position)
  end
end

#running_as(user) ⇒ Object

Run as the specified user for the duration of the block.



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# File 'lib/bolt/shell/bash.rb', line 279

def running_as(user)
  @run_as = user
  yield
ensure
  @run_as = nil
end

#sudo_prompt ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 502

def sudo_prompt
  '[sudo] Bolt needs to run as another user, password: '
end

#sudo_success(sudo_id) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 331

def sudo_success(sudo_id)
  "echo #{sudo_id} 1>&2"
end

#upload(source, destination, options = {}) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 34

def upload(source, destination, options = {})
  running_as(options[:run_as]) do
    with_tmpdir do |dir|
      basename = File.basename(source)
      tmpfile = File.join(dir.to_s, basename)
      conn.upload_file(source, tmpfile)
      # pass over file ownership if we're using run-as to be a different user
      dir.chown(run_as)
      result = execute(['mv', '-f', tmpfile, destination], sudoable: true)
      if result.exit_code != 0
        message = "Could not move temporary file '#{tmpfile}' to #{destination}: #{result.stderr.string}"
        raise Bolt::Node::FileError.new(message, 'MV_ERROR')
      end
    end
    Bolt::Result.for_upload(target, source, destination)
  end
end

#with_tmpdir(force_cleanup: false) ⇒ Object

A helper to create and delete a tmpdir on the remote system. Yields the directory name.



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# File 'lib/bolt/shell/bash.rb', line 318

def with_tmpdir(force_cleanup: false)
  dir = make_tmpdir
  yield dir
ensure
  if dir
    if target.options['cleanup'] || force_cleanup
      dir.delete
    else
      Bolt::Logger.warn("skip_cleanup", "Skipping cleanup of tmpdir #{dir}")
    end
  end
end

#write_executable(dir, file, filename = nil) ⇒ Object 



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# File 'lib/bolt/shell/bash.rb', line 308

def write_executable(dir, file, filename = nil)
  filename ||= File.basename(file)
  remote_path = File.join(dir.to_s, filename)
  conn.upload_file(file, remote_path)
  make_executable(remote_path)
  remote_path
end