cf-cmd - A tool for running CFEngine snippets

cf-cmd.rb

#!/usr/bin/env ruby
#
# CFengine command-line test utility.
#
# Diego Zamboni, December 27th, 2011
#
# Run as "cf-cmd help" to see usage information.

require 'readline'
require 'tmpdir'

######################################################################
# ATTENTION: customize this if necessary

# Where can I find a copy of cfengine_stdlib.cf
# $stdlib_loc = "#{ENV['HOME']}/CFEngine/src/copbl/cfengine_stdlib.cf";
$stdlib_loc = "/var/cfengine/inputs/cfengine_stdlib.cf";

######################################################################

class CfCmd

  # Constructor
  def initialize(stdlib, initialstate = 'reports:')
    @version = "1.0";
    # Initialize base parameters
    @stdlib_loc = stdlib
    @initialstate = initialstate
    @mode = @initialstate

    # Valid promise types and commands
    @modes = %w(vars: classes: commands: databases: environments: files: interfaces:
                methods: outputs: packages: processes: services: storage: reports:)

    @commands = self.methods(/^cmd_/).grep(/^cmd_/).map { |c| c.to_s.gsub(/^cmd_/, "") }

    # Initialize data structures
    @lines = emptypolicy
    # By default, initialize the reports: section with a cfengine:: class, so that things are always printed.
    # Issue a "clear" command to eliminate it.
    @lines['reports:'] = "cfengine::\n"
  end

  #----------------------------------------------------------------------
  # Utility functions

  # Policy template to use
  def policytemplate(bundlebody)
    <<EOF
body common control
{
   inputs => { "#{ @stdlib_loc }" };
   bundlesequence => { "test" };
}
 
bundle agent test
{
#{bundlebody}}
EOF
  end

  # Return current policy as a string
  def buildpolicy
    bundlebody = ""
    @lines.keys.each { |k|
      bundlebody += "#{k}\n#{@lines[k]}" unless @lines[k].empty?
    }
    return policytemplate(bundlebody)
  end

  # Empty all policy sections
  def emptypolicy
    res = {}
    @modes.each { |m|
      res[m] = ""
    }
    return res
  end

  # Find the first command (if any) that start with the given string
  def findcmd(cmd)
    cmds = @commands.grep(/^#{Regexp.quote(cmd)}/)
    return cmds.empty? ? nil : cmds[0]
  end

  # Word wrap, with an optional prefix string. Based on http://snipplr.com/view.php?codeview&id=1081
  def wrap_text(txt, col = 80, prefix="") 
    ncol = col - prefix.length
    txt.gsub(/(.{1,#{ncol}})( +|$\n?)|(.{1,#{ncol}})/, "#{prefix}\\1\\3\n") 
  end

  # Interpret and process a line 
  def interpret(line)
      (cmd, args) = line.split(nil, 2)
      if @modes.include?(cmd)
        $stderr.puts "-> Switching to #{cmd} promise type."
        @mode = cmd
      elsif cmdname = findcmd(cmd)
        eval "cmd_#{cmdname}(args)"
      else
        @lines[@mode] = @lines[@mode] + "  #{line}\n"
      end
  end

  #----------------------------------------------------------------------
  # Command definitions

  # List current policy
  def cmd_list(args=nil)
    puts "#{buildpolicy}";
  end

  # Clear current policy
  def cmd_clear(args=nil)
    @lines = emptypolicy
  end

  # Execute current policy
  def cmd_go(args=nil)
    fname = "./test.cf"
    Dir.mktmpdir('cf-') { |dir|
      Dir.chdir(dir)
      File.open(fname, "w") { |f| f.puts(buildpolicy) }
      cmd = "cf-agent #{args.to_s} -KI -f #{fname}"
      $stderr.puts "-> Running policy with '#{cmd}'"
      system(cmd)
    }
  end

  # Synonymous for go
  def cmd_run(args=nil)
    cmd_go(args)
  end

  # Save to a file
  def cmd_save(args=nil)
    if args.nil?
      $stderr.puts "-> Error: need a filename to which to save the script."
    else
      File.open(args, "w") { |f| f.puts(buildpolicy) }
      $stderr.puts "-> Saved script to #{args}."
    end
  end

  # Print help
  def cmd_help(args=nil)
    cmdname=File.basename($0)
    puts <<EOM
#{cmdname} v#{@version} - Diego Zamboni <[email protected]>

#{cmdname} is a tool that allows you to run small CFEngine snippets quickly,
by automatically wrapping them around a standard "test" bundle.

The CFEngine Standard Library is automatically included.

The following inputs are understood by this tool:

help     Print this message
list     Print current policy
clear    Clear current policy
go|run   Execute current policy using cf-agent
type:    Switch to the given promise type
#{wrap_text("(" + @modes.sort.join(', ') +")", 80, '         ').chomp}
           The current promise type is shown in the prompt.

All other lines are added literally to the current promise type.

Commands can be abbreviated to any part of their name (for example,
"r" or "ru" for "run").

You can add lines to any of the standard promise types inside the test
bundle by switching to the appropriate promise type first.

The default promise type is "reports:", to make it easier to quickly print
the value of expressions.

You can give the inputs also on the command line, they are interpreted
in exactly the same way (make sure to quote things correctly).

Examples:
  #{cmdname} '"Flavor: $(sys.flavor)";' list run
  #{cmdname} '"var1 = $(var1)";' vars: '"var1" string => "test";' l r
  #{cmdname} h
EOM
  end

  #----------------------------------------------------------------------
  # Interactive subroutine

  def run
    # Trap Ctrl-C and make it do a clean exit
    stty_save = `stty -g`.chomp
    trap('INT') { system('stty', stty_save); exit }

    comp = proc { |s| (@commands + @modes).grep( /^#{Regexp.escape(s)}/ ) }

    Readline.completion_append_character = " "
    Readline.completion_proc = comp

    while line = Readline.readline("#{@mode} > ", true)
      interpret(line)
    end
  end

end # class CfCmd


# Do something if invoked directly (instead of included as a module)
if __FILE__ == $0
  cfcmd = CfCmd.new($stdlib_loc)
  if !ARGV.empty?
    # If any command-line arguments are given, interpret them as commands
    ARGV.each { |cmd|
      cfcmd.interpret(cmd)
    }
  else
    # Otherwise start interactive mode
    cfcmd.run
  end
end