Simple nixos-rebuild deployments

deploy.cr

require "file_utils"

class Ops
  property hosts : Array(String)

  def initialize(host : String)
    @hosts = [host]
  end

  HOSTS = Dir["box_*.nix"].map { |h| h[/^box_(.*)\.nix$/, 1] }

  def initialize(host : Nil)
    if HOSTS.empty?
      STDERR.puts "Please specifiy a host by creating a box_nameofyourhost.nix file"
      exit 1
    end

    @hosts = HOSTS
  end

  def run(cmd : String, args : Array(String), env : Hash(String, String))
    puts "#{cmd} #{args.join(" ")}"
    output = [] of String

    Process.run cmd, args: args, env: env do |cmd|
      spawn do
        cmd.output.each_line do |line|
          output << line
          puts line
        end
      end

      spawn do
        cmd.error.each_line do |line|
          STDERR.puts line
        end
      end
    end

    output
  end

  def run(cmd : String, args : Array(String))
    run cmd, args: args, env: ({} of String => String)
  end

  def run_ssh_each(args : Array(String))
    hosts.map do |host|
      run("ssh", args: [host] + args)
    end
  end

  def nixos_rebuild(subcmd)
    hosts.each do |host|
      run "nixos-rebuild",
        args: ["--build-host", host, "--target-host", host, subcmd],
        env: {"NIXOS_CONFIG" => "#{FileUtils.pwd}/box_#{host}.nix"}
    end
  end

  def switch
    nixos_rebuild("switch")
  end

  def build
    nixos_rebuild("build")
  end

  def status
    run_ssh_each(["systemctl", "status"])
  end

  def failed
    run_ssh_each(["systemctl", "list-units", "--state=failed"]).each do |output|
      output.each do |line|
        #   UNIT          LOAD   ACTIVE SUB    DESCRIPTION
        # ● gitea.service loaded failed failed gitea
        words = line.split
        next if words.size != 6
        _, unit, load, active, sub, desc = words
        next if unit.nil?
      end
    end
  end
end

ops = Ops.new(ARGV[1]?)

case ARGV[0]?
when "switch"
  ops.switch
when "build"
  ops.build
when "status"
  ops.status
when "failed"
  ops.failed
else
  STDERR.puts "You must specify a command like (switch|status)"
  exit 1
end