Knife remote command

Recntly we switched from chef-solo to a chef-server setup on our infrastructure, a good occasion to refactor our recipes to better practices. I spent some time figuring out how to replace the fabric scripts I had for remote execution of actions on various servers, by using a knife plugin. That way I can just use knife abilities and don’t need fabric anymore.

So I created a new file in .chef/plugins/knife/ named apt.rb for a test:

require 'chef/knife'

module KnifeOpenvpn
  class Apt < Chef::Knife

    banner "knife apt <update|upgrade|simulate> <nodename>"

    deps do
      require 'chef/knife/ssh'
      require 'chef/node'
      Chef::Knife::Ssh.load_deps
    end

    def run
      if name_args.size == 2
        command_arg = name_args.shift
        server = name_args.shift
      else
        ui.fatal "Syntax: knife apt <update|upgrade|simulate> <nodename>"
        ui.fatal "Where <nodename> is a node name."
        exit 1
      end
      command = case command_arg
                when 'update'
                  'update'
                when 'upgrade'
                  '-y upgrade'
                when 'simulate'
                  '-y -s upgrade'
                end
      knife_ssh(Chef::Node.load(server).ipaddress, "sudo apt-get #{command}").run
    end

    def knife_ssh(server, command)
      ssh = Chef::Knife::Ssh.new
      ssh.name_args = [ server, command ]
      ssh.config[:ssh_user] = Chef::Config[:knife][:ssh_user]
      ssh.config[:ssh_port] = Chef::Config[:knife][:ssh_port]
      ssh.config[:identity_file] = Chef::Config[:knife][:identity_file]
      ssh.config[:ssh_gateway] = Chef::Config[:knife][:ssh_gateway]
      ssh.config[:manual] = true
      ssh.config[:host_key_verify] = Chef::Config[:knife][:host_key_verify]
      ssh.config[:on_error] = :raise
      ssh
    end

  end

end

Then I just run a knife apt simulate my-server to execute a apt-get -s -y upgrade on the my-server client node. Pretty useful. But I guess that’s only a beginning, I should extend it to run on various nodes at the same time and maybe inside threads or something like that, to match the fabric power.

Knife remote command when working with chef-server