Class: Synapse::Haproxy

Inherits:
Object
  • Object
show all
Defined in:
lib/synapse/haproxy.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts) ⇒ Haproxy

Returns a new instance of Haproxy.



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# File 'lib/synapse/haproxy.rb', line 6

def initialize(opts)
  super()

  %w{global defaults reload_command}.each do |req|
    raise ArgumentError, "haproxy requires a #{req} section" if !opts.has_key?(req)
  end

  req_pairs = {
    'do_writes' => 'config_file_path',
    'do_socket' => 'socket_file_path',
    'do_reloads' => 'reload_command'}

  req_pairs.each do |cond, req|
    if opts[cond]
      raise ArgumentError, "the `#{req}` option is required when `#{cond}` is true" unless opts[req]
    end
  end

  @opts = opts
  @restart_required = true
end

Instance Attribute Details

#opts ⇒ Object (readonly)

Returns the value of attribute opts.



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# File 'lib/synapse/haproxy.rb', line 5

def opts
  @opts
end

Instance Method Details

#generate_base_config ⇒ Object

generates the global and defaults sections of the config file



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# File 'lib/synapse/haproxy.rb', line 56

def generate_base_config
  base_config = "# auto-generated by synapse at #{Time.now}\n"

  %w{global defaults}.each do |section|
    base_config << "\n#{section}\n"
    @opts[section].each do |option|
      base_config << "\t#{option}\n"
    end
  end

  if @opts['extra_sections']
    @opts['extra_sections'].each do |title, section|
      base_config << "\n#{title}\n"
      section.each do |option|
        base_config << "\t#{option}\n"
      end
    end
  end

  return base_config
end

#generate_config(watchers) ⇒ Object

generates a new config based on the state of the watchers



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# File 'lib/synapse/haproxy.rb', line 47

def generate_config(watchers)
  new_config = generate_base_config + "\n"
  new_config << watchers.map {|w| generate_listen_stanza(w)}.join("\n")

  log.debug "synapse: new haproxy config: #{new_config}"
  return new_config
end

#generate_listen_stanza(watcher) ⇒ Object

generates an individual stanza for a particular watcher



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# File 'lib/synapse/haproxy.rb', line 79

def generate_listen_stanza(watcher)
  if watcher.backends.empty?
    log.warn "synapse: no backends found for watcher #{watcher.name}"
    return ""
  end

  stanza = "listen #{watcher.name} localhost:#{watcher.local_port}\n"

  watcher.listen.each do |line|
    stanza << "\t#{line}\n"
  end

  watcher.backends.shuffle.each do |backend|
    stanza << "\tserver #{backend['name']} #{backend['host']}:#{backend['port']} #{watcher.server_options}\n"
  end

  return stanza
end

#restart ⇒ Object

restarts haproxy



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# File 'lib/synapse/haproxy.rb', line 194

def restart
  res = `#{opts['reload_command']}`.chomp
  raise "failed to reload haproxy via #{opts['reload_command']}: #{res}" unless $?.success?
  @restart_required = false
end

#update_backends(watchers) ⇒ Object

tries to set active backends via haproxy’s stats socket because we can’t add backends via the socket, we might still need to restart haproxy



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# File 'lib/synapse/haproxy.rb', line 100

def update_backends(watchers)
  # first, get a list of existing servers for various backends
  begin
    s = UNIXSocket.new(@opts['socket_file_path'])
    s.write('show stat;')
    info = s.read()
  rescue StandardError => e
    log.warn "synapse: unhandled error reading stats socket: #{e.inspect}"
    @restart_required = true
    return
  end

  # parse the stats output to get current backends
  cur_backends = {}
  info.split("\n").each do |line|
    next if line[0] == '#'

    parts = line.split(',')
    next if ['FRONTEND', 'BACKEND'].include?(parts[1])

    cur_backends[parts[0]] ||= []
    cur_backends[parts[0]] << parts[1]
  end

  # build a list of backends that should be enabled
  enabled_backends = {}
  watchers.each do |watcher|
    enabled_backends[watcher.name] = []
    next if watcher.backends.empty?

    unless cur_backends.include? watcher.name
      log.debug "synapse: restart required because we added new section #{watcher.name}"
      @restart_required = true
      return
    end

    watcher.backends.each do |backend|
      unless cur_backends[watcher.name].include? backend['name']
        log.debug "synapse: restart required because we have a new backend #{watcher.name}/#{backend['name']}"
        @restart_required = true
        return
      end

      enabled_backends[watcher.name] << backend['name']
    end
  end

  # actually enable the enabled backends, and disable the disabled ones
  cur_backends.each do |section, backends|
    backends.each do |backend|
      if enabled_backends[section].include? backend
        command = "enable server #{section}/#{backend};"
      else
        command = "disable server #{section}/#{backend};"
      end

      # actually write the command to the socket
      begin
        s = UNIXSocket.new(@opts['socket_file_path'])
        s.write(command)
        output = s.read()
      rescue StandardError => e
        log.warn "synapse: unknown error writing to socket"
        @restart_required = true
        return
      else
        unless output == "\n"
          log.warn "synapse: socket command #{command} failed: #{output}"
          @restart_required = true
          return
        end
      end
    end
  end
end

#update_config(watchers) ⇒ Object 



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# File 'lib/synapse/haproxy.rb', line 28

def update_config(watchers)
  # if we support updating backends, try that whenever possible
  if @opts['do_socket']
    update_backends(watchers) unless @restart_required
  else
    @restart_required = true
  end

  # generate a new config
  new_config = generate_config(watchers)

  # if we write config files, lets do that and then possibly restart
  if @opts['do_writes']
    write_config(new_config)
    restart if @opts['do_reloads'] && @restart_required
  end
end

#write_config(new_config) ⇒ Object

writes the config



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# File 'lib/synapse/haproxy.rb', line 177

def write_config(new_config)
  begin
    old_config = File.read(@opts['config_file_path'])
  rescue Errno::ENOENT => e
    log.info "synapse: could not open haproxy config file at #{@opts['config_file_path']}"
    old_config = ""
  end

  if old_config == new_config
    return false
  else
    File.open(@opts['config_file_path'],'w') {|f| f.write(new_config)}
    return true
  end
end