sm.rb

#!/usr/bin/ruby
# 20140830 rschmutz@netlabs.ch
module SM

  require "pstore"

  # monkey-patch String.match?
  class String
    def match?(regex)
      !!self.match(regex)
    end
  end

  # control collection of services

  class Controller
    @services = []
    @states = nil

    private
    def filter(pattern)
      if pattern.nil?
        @services
      else
        @services.select do |service|
          if service.description.match?(pattern) or service.name.match?(pattern) or service.state.to_s.match?(pattern)
            true
          else
            false
          end
        end
      end
    end

    private
    def add_service(service)
      @services << service
      @states.transaction do
        begin
          service.state = @states[service.name]
        rescue
          @states[service.name] = service.state
          @states.commit
        end
      end
    end

    public
    def initialize(directory)
      @states = PStore.new(directory + "/" + ".states")
      @services = Array.new
      Dir.foreach directory do |file|
        next if file.match /^\./
          service = Service.new
        service.configure do
          eval(File.open(directory + "/" + file).read)
          if name.nil? # no identifier given, use the file name instead
            identifier file
          end
        end
        service.file = directory + "/" + file
        add_service service
      end
    end

    private
    def start_service(service)
      service.start_commands.each do |command|
        service.processes << fork do
          exec command
        end
      end
      service.processes.each { |pid| Process::detach pid }
      @states.transaction do
        @states[service.name] = (service.state = :running)
        @states.commit
      end
    end

    public
    def start(pattern = nil)
      filter(pattern).each do |service|
        start_service service
      end
    end

    private
    def stop_service(service)
      if service.stop_commands.empty? # kill processes the old way
        pid_from_files = service.pidfiles.collect do |pidfile|
          begin
            File.read(pidfile)
          rescue
          end
        end
        (service.processes & pid_from_files).each do |pid|
          begin
            Process::kill "KILL", pid
          rescue
          end
        end
      else # use provided stop commands
        service.stop_commands.each do |command|
          system command
        end
      end
      @states.transaction do
        @states[service.name] = service.state = :stopped
        @states.commit
      end
    end

    public
    def stop(pattern = nil)
      filter(pattern).each do |service|
        stop_service service
      end
    end

    private
    def status_service(service)
      check = nil
      if service.status_commands.empty? # kill processes the old way
        if service.pidfiles.empty?
          pids = service.processes
        else
          pids = service.pidfiles.collect do |pidfile|
            begin
              File.read(pidfile)
            rescue
            end
          end
        end
        if pids.all? do |pid|
          begin
            Process::kill 0, pid
            check = :running 
          rescue
            check = :stopped
          end
        end
        end
      else # use provided status commands
        service.status_commands.all? do |command|
          fork { exec command }
        end
      end
      result = :unknown
      if service.state != :uninitialized
        if check == service.state
          result = :running
        else
          result = :stopped
        end
      end
      return result
    end

    public
    def status(pattern = nil)
      printf "%-20s%-15s%s\n", "service", "state", "check"
      printf "%--20s%--15s%s\n", "-------", "-----", "-----"
      filter(pattern).each do |service|
        state = status_service service
        printf "%-20s%-15s%s\n", service.name, service.state.to_s, state.to_s
      end
    end

    public
    def services(pattern = nil)
      printf "%-20s%s\n", "service", "definition-file"
      printf "%-20s%s\n", "-------", "---------------"
      @services.each do |service|
        printf "%-20s%s\n", service.name, service.file
      end
    end

    private
    def synchronize_service(service) # ensure service state match persistent state, ie start services in running state
      @states.transaction(true) do # read-only
        begin
          if @states[service.name] == :running
            state = status_service service
            if state != :running
              start_service service
            end
          end
        rescue
        end
      end
    end
  end




  # container class for a (single despite the legacy arrays) service

  class Service
    attr_reader :name, :start_commands, :stop_commands, :status_commands, :pidfiles
    attr_accessor :state, :processes, :file, :description
    @description = ""
    @name = ""
    @processes = []
    @start_commands = []
    @stop_commands = []
    @status_commands = []
    @state = :down
    @file = ""
    @pidfiles = []

    def initialize
      @start_commands = Array.new
      @stop_commands = Array.new
      @status_commands = Array.new
      @pidfiles = Array.new
      @processes = Array.new
      @state = :uninitialized
      @description = ""
    end

    def configure(&block)
      instance_eval &block
    end

    #  def description(description)
    #    @description = description
    #  end

    def identifier(name)
      @name = name
    end

    def start(command)
      @start_commands << command
    end

    def stop(command)
      @stop_commands << command
    end

    def status(command)
      @status_commands << command
    end

    def pidfile(pidfile)
      @pidfiles << pidfile
    end

  end

end

# 
# sockets socket | [ socket socket... ]
# states: down starting faulty running disabled stopping
# connections remote-socket
# 
# render
# logging
# notfication