ops/provision.nix

# Top-level wrapper script for calling per-machine provisioners.
#
# Given ops.machines."edge01.waw.bgp.wtf".config.passthru.hscloud.provision,
# this script allows to run it by doing:
#   $ $(nix-build -A ops.provision) edge01.waw.bgp.wtf
# Or, to first list all available machines by doing:
#   $ $(nix-build -A ops.provision)
#
# The main logic of the provisioner script is in machines.nix.

{ hscloud, pkgs, lib, ... }:

with lib; with builtins;

let

  # All machines from ops.machines, keyed by FQDN.
  machines = filterAttrs (n: _: n != "__readTree") hscloud.ops.machines;
  # Machines' provisioner scripts, keyed by machine FQDN.
  machineProvisioners = mapAttrs (_: v: v.config.passthru.hscloud.provision) machines;
  # List of machine FQDNs.
  machineNames = attrNames machines;

  # User-friendly list of machines by FQDN.
  machineList = concatStringsSep "\n"
    (map
      (name: "  - ${name}")
      machineNames);

  # Derivation containing bin/provision-FQDN symlinks to machines' provisioners.
  forest = pkgs.linkFarm "provision-forest"
    (mapAttrsToList
      (fqdn: p: { name = "bin/provision-${fqdn}"; path = p; })
      machineProvisioners);
in

pkgs.writeScript "provision" ''
  #!/bin/sh
  name="$1"

  usage() {
    echo >&2 "Usage: $0 machine|machine.hswaw.net"
    echo >&2 "Available machines:"
    echo >&2 "${machineList}"
  }

  if [ -z "$name" ]; then
    usage
    exit 1
  fi

  provisioner="${forest}/bin/provision-$name"
  if [ ! -e "$provisioner" ]; then
    name="$name.hswaw.net"
    provisioner="${forest}/bin/provision-$name"
  fi
  if [ ! -e "$provisioner" ]; then
    usage
    exit 1
  fi
  # :^)
  echo -ne "\e[34mh \e[31ms \e[33mc l \e[34mo \e[32mu \e[31md \e[0m"
  echo ""
  echo "Starting provisioner for $name..."
  echo ""
  echo "Too slow to evaluate? Equivalent faster command line that rebuilds just one node:"
  echo "  \$(nix-build -A 'ops.machines.\"$name\".config.passthru.hscloud.provision')"
  echo ""
  echo "Or, if you want to deploy the same configuration on different machines, just run"
  echo "this script again without re-evaluating nix:"
  echo "  $0 $name"
  echo ""
  exec "$provisioner"
''