option-one.pp

class system-update {
  exec { 'apt-get update':
    command => 'apt-get update',
    path => ['/usr/bin', '/bin', '/usr/sbin', '/sbin'],
  }

  Exec['apt-get update'] -> Package<| |> # before all packages

  $sysPackages = [ "build-essential", "nmap", "skipfish", "curl", "libcurl4-openssl-dev" ]
  package { $sysPackages:
    ensure => "installed",
  }
}

class mongodb {
  package { "mongodb":
    ensure  => present,
  }
  service { "mongodb":
    ensure  => "running",
    require => Package["mongodb"],
  }
}

class rabbitmq {
  package { "rabbitmq-server":
    ensure  => present,
  }
  service { "rabbitmq-server":
    ensure  => "running",
    require => Package["rabbitmq-server"],
  }
}

include system-update
include mongodb
include rabbitmq

option-two.pp

class system-update {
  exec { 'apt-get update':
    command => 'apt-get update',
    path => ['/usr/bin', '/bin', '/usr/sbin', '/sbin'],
  }

  $sysPackages = [ "build-essential", "nmap", "skipfish", "curl", "libcurl4-openssl-dev" ]
  package { $sysPackages:
    ensure => "installed",
    require => Exec['apt-get update'],
  }
}

class mongodb {
  require 'system-update'

  package { "mongodb":
    ensure  => present,
  }
  service { "mongodb":
    ensure  => "running",
    require => Package["mongodb"],
  }
}

class rabbitmq {
  require 'system-update'

  package { "rabbitmq-server":
    ensure  => present,
  }
  service { "rabbitmq-server":
    ensure  => "running",
    require => Package["rabbitmq-server"],
  }
}

include mongodb
include rabbitmq