Module: Chef::Mixin::Command

Included in:
Provider::Cron, Provider::Deploy, Provider::ErlCall, Provider::Execute, Provider::Git, Provider::Group, Provider::Ifconfig, Provider::Link, Provider::Mdadm, Provider::Mount, Provider::Mount::Mount, Provider::Package, Provider::Package::Yum::YumCache, Provider::Route, Provider::Service, Provider::Subversion, Provider::User
Defined in:
lib/chef/mixin/command.rb

Class Method Summary collapse

Class Method Details

.handle_command_failures(status, command_output, args = {}) ⇒ Object 



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# File 'lib/chef/mixin/command.rb', line 164

def handle_command_failures(status, command_output, args={})
  unless args[:ignore_failure] 
    args[:returns] ||= 0
    if status.exitstatus != args[:returns]
      # if the log level is not debug, through output of command when we fail
      output = ""
      if Chef::Log.logger.level > 0
        output << "\n---- Begin output of #{args[:command]} ----\n"
        output << "#{command_output}"
        output << "---- End output of #{args[:command]} ----\n"
      end
      raise Chef::Exceptions::Exec, "#{args[:command]} returned #{status.exitstatus}, expected #{args[:returns]}#{output}"
    end
  end
end

.not_if(command) ⇒ Object

If command is a block, returns false if the block returns true, true if it returns false. (“Do not run this resource if the block is true”)

If the command is not a block, executes the command. If it returns a 0 exitstatus, returns false. (“Do not run this resource if the command returns 0”)

Parameters

command<Block>, <String>

A block to check, or a string to execute

Returns

true

Returns true if the block is false, or if the command returns a non-zero exit status.

false

Returns false if the block is true, or if the command returns a 0 exit status.



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# File 'lib/chef/mixin/command.rb', line 71

def not_if(command)
  if command.kind_of?(Proc)
    res = command.call
    if res
      return false
    end
  else  
    status = run_command(:command => command, :ignore_failure => true)
    if status.exitstatus == 0
      return false
    end
  end
  true
end

.only_if(command) ⇒ Object

If command is a block, returns true if the block returns true, false if it returns false. (“Only run this resource if the block is true”)

If the command is not a block, executes the command. If it returns any status other than 0, it returns false (clearly, a 0 status code is true)

Parameters

command<Block>, <String>

A block to check, or a string to execute

Returns

true

Returns true if the block is true, or if the command returns 0

false

Returns false if the block is false, or if the command returns a non-zero exit code.



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# File 'lib/chef/mixin/command.rb', line 42

def only_if(command)
  if command.kind_of?(Proc)
    res = command.call
    unless res
      return false
    end
  else  
    status = run_command(:command => command, :ignore_failure => true)
    if status.exitstatus != 0
      return false
    end
  end
  true
end

.output_of_command(command, args) ⇒ Object 



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# File 'lib/chef/mixin/command.rb', line 125

def output_of_command(command, args)
  Chef::Log.debug("Executing #{command}")
  stderr_string, stdout_string, status = "", "", nil
  
  exec_processing_block = lambda do |pid, stdin, stdout, stderr|
    stdout_string, stderr_string = stdout.string.chomp, stderr.string.chomp
  end
  
  args[:cwd] ||= Dir.tmpdir
  unless File.directory?(args[:cwd])
    raise Chef::Exceptions::Exec, "#{args[:cwd]} does not exist or is not a directory"
  end
  
  Dir.chdir(args[:cwd]) do
    if args[:timeout]
      begin
        Timeout.timeout(args[:timeout]) do
          status = popen4(command, args, &exec_processing_block)
        end
      rescue Timeout::Error => e
        Chef::Log.error("#{command} exceeded timeout #{args[:timeout]}")
        raise(e)
      end
    else
      status = popen4(command, args, &exec_processing_block)
    end
    
    Chef::Log.debug("---- Begin output of #{command} ----")
    Chef::Log.debug("STDOUT: #{stdout_string}")
    Chef::Log.debug("STDERR: #{stderr_string}")
    Chef::Log.debug("---- End output of #{command} ----")
    Chef::Log.debug("Ran #{command} returned #{status.exitstatus}")
  end
  
  return status, stdout_string, stderr_string
end

.popen4(cmd, args = {}, &b) ⇒ Object

This is taken directly from Ara T Howard’s Open4 library, and then modified to suit the needs of Chef. Any bugs here are most likely my own, and not Ara’s.

The original appears in external/open4.rb in its unmodified form.

Thanks Ara!



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# File 'lib/chef/mixin/command.rb', line 204

def popen4(cmd, args={}, &b)
 
  # Waitlast - this is magic.  
  # 
  # Do we wait for the child process to die before we yield
  # to the block, or after?  That is the magic of waitlast.
  #
  # By default, we are waiting before we yield the block.
  args[:waitlast] ||= false
  
  args[:user] ||= nil
  unless args[:user].kind_of?(Integer)
    args[:user] = Etc.getpwnam(args[:user]).uid if args[:user]
  end
  args[:group] ||= nil
  unless args[:group].kind_of?(Integer)
    args[:group] = Etc.getgrnam(args[:group]).gid if args[:group]
  end
  args[:environment] ||= {}

  # Default on C locale so parsing commands output can be done
  # independently of the node's default locale.
  # "LC_ALL" could be set to nil, in which case we also must ignore it.
  unless args[:environment].has_key?("LC_ALL")
    args[:environment]["LC_ALL"] = "C"
  end
  
  pw, pr, pe, ps = IO.pipe, IO.pipe, IO.pipe, IO.pipe

  verbose = $VERBOSE
  begin
    $VERBOSE = nil
    ps.last.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC)

    cid = fork {
      pw.last.close
      STDIN.reopen pw.first
      pw.first.close

      pr.first.close
      STDOUT.reopen pr.last
      pr.last.close

      pe.first.close
      STDERR.reopen pe.last
      pe.last.close

      STDOUT.sync = STDERR.sync = true

      if args[:group]
        Process.egid = args[:group]
        Process.gid = args[:group]
      end

      if args[:user]
        Process.euid = args[:user]
        Process.uid = args[:user]
      end
      
      args[:environment].each do |key,value|
        ENV[key] = value
      end

      if args[:umask]
        umask = ((args[:umask].respond_to?(:oct) ? args[:umask].oct : args[:umask].to_i) & 007777)
        File.umask(umask)
      end
      
      begin
        if cmd.kind_of?(Array)
          exec(*cmd)
        else
          exec(cmd)
        end
        raise 'forty-two' 
      rescue Exception => e
        Marshal.dump(e, ps.last)
        ps.last.flush
      end
      ps.last.close unless (ps.last.closed?)
      exit!
    }
  ensure
    $VERBOSE = verbose
  end

  [pw.first, pr.last, pe.last, ps.last].each{|fd| fd.close}

  begin
    e = Marshal.load ps.first
    raise(Exception === e ? e : "unknown failure!")
  rescue EOFError # If we get an EOF error, then the exec was successful
    42
  ensure
    ps.first.close
  end

  pw.last.sync = true

  pi = [pw.last, pr.first, pe.first]

  if b 
    begin
      if args[:waitlast]
        b[cid, *pi]
        # send EOF so that if the child process is reading from STDIN
        # it will actually finish up and exit
        pi[0].close_write
        Process.waitpid2(cid).last
      else
        # This took some doing.
        # The trick here is to close STDIN
        # Then set our end of the childs pipes to be O_NONBLOCK
        # Then wait for the child to die, which means any IO it
        # wants to do must be done - it's dead.  If it isn't,
        # it's because something totally skanky is happening,
        # and we don't care.
        o = StringIO.new
        e = StringIO.new

        pi[0].close
        
        stdout = pi[1]
        stderr = pi[2]

        stdout.sync = true
        stderr.sync = true

        stdout.fcntl(Fcntl::F_SETFL, pi[1].fcntl(Fcntl::F_GETFL) | Fcntl::O_NONBLOCK)
        stderr.fcntl(Fcntl::F_SETFL, pi[2].fcntl(Fcntl::F_GETFL) | Fcntl::O_NONBLOCK)
        
        stdout_finished = false
        stderr_finished = false
       
        results = nil

        while !stdout_finished || !stderr_finished
          begin
            channels_to_watch = []
            channels_to_watch << stdout if !stdout_finished
            channels_to_watch << stderr if !stderr_finished
            ready = IO.select(channels_to_watch, nil, nil, 1.0)
          rescue Errno::EAGAIN
          ensure
            results = Process.waitpid2(cid, Process::WNOHANG)
            if results
              stdout_finished = true
              stderr_finished = true 
            end
          end

          if ready && ready.first.include?(stdout)
            line = results ? stdout.gets(nil) : stdout.gets
            if line
              o.write(line)
            else
              stdout_finished = true
            end
          end
          if ready && ready.first.include?(stderr)
            line = results ? stderr.gets(nil) : stderr.gets
            if line
              e.write(line)
            else
              stderr_finished = true
            end
          end
        end
        results = Process.waitpid2(cid) unless results
        o.rewind
        e.rewind
        b[cid, pi[0], o, e]
        results.last
      end
    ensure
      pi.each{|fd| fd.close unless fd.closed?}
    end
  else
    [cid, pw.last, pr.first, pe.first]
  end
end

.run_command(args = {}) ⇒ Object

Parameters

args<Hash>: A number of required and optional arguments

command<String>, <Array>: A complete command with options to execute or a command and options as an Array 
creates<String>: The absolute path to a file that prevents the command from running if it exists
cwd<String>: Working directory to execute command in, defaults to Dir.tmpdir
timeout<String>: How many seconds to wait for the command to execute before timing out
returns<String>: The single exit value command is expected to return, otherwise causes an exception
ignore_failure<Boolean>: Whether to raise an exception on failure, or just return the status

user<String>: The UID or user name of the user to execute the command as
group<String>: The GID or group name of the group to execute the command as
environment<Hash>: Pairs of environment variable names and their values to set before execution

Returns

Returns the exit status of args



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# File 'lib/chef/mixin/command.rb', line 103

def run_command(args={})         
  command_output = ""
  
  args[:ignore_failure] ||= false

  if args.has_key?(:creates)
    if File.exists?(args[:creates])
      Chef::Log.debug("Skipping #{args[:command]} - creates #{args[:creates]} exists.")
      return false
    end
  end
  
  status, stdout, stderr = output_of_command(args[:command], args)
  command_output << "STDOUT: #{stdout}"
  command_output << "STDERR: #{stderr}"
  handle_command_failures(status, command_output, args)
  
  status
end

.run_command_with_systems_locale(args = {}) ⇒ Object

Call #run_command but set LC_ALL to the system’s current environment so it doesn’t get changed to C.

Parameters

args<Hash>: A number of required and optional arguments that will be handed out to #run_command

Returns

Returns the result of #run_command



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# File 'lib/chef/mixin/command.rb', line 189

def run_command_with_systems_locale(args={})
  args[:environment] ||= {}
  args[:environment]["LC_ALL"] = ENV["LC_ALL"]
  run_command args
end