do-float-ip

#!/bin/bash
set -euo pipefail

DO_API="https://api.digitalocean.com"
DO_TOKEN=

CURL="curl -LSsf"
DROPLET_ID=$($CURL "http://169.254.169.254/metadata/v1/id")
REGION=$($CURL "http://169.254.169.254/metadata/v1/region")

fatal() {
  echo "Fatal: $@" >&2
  exit 1
}

ocean() {
  local action=$1
  local path=$2
  shift 2
  args=$(echo "$@" | sed 's/\([^ ][^=]*\)=\([^ ]*\)/"\1": "\2",/g;s/,$//')
  $CURL -X "$action" "$DO_API/$path" \
    -H 'Content-Type: application/json' \
    -H "Authorization: Bearer $DO_TOKEN" \
    -d "{ $args }" 2>&1 # If curl suceeds, output is only stdout. If fails, only stderr
}

main() {
  [[ "$#" -lt 1 ]] && fatal "$0 floating-ip-or-name"
  local ip=$1

  DO_TOKEN=$(cat /secret/do.token 2>/dev/null) \
    || fatal "/secret/do.token missing or unreadable"

  if [[ ! "$ip" =~ "^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$" ]]; then
    ip="$(getent hosts "$ip" | sed 's/ .*$//')"
  fi

  while true; do
    local assigned_to=$(ocean GET "v2/floating_ips/$ip" | jq -r .floating_ip.droplet.id)
    if [[ "$assigned_to" != "$DROPLET_ID" ]]; then
      echo "$ip assigned to $assigned_to, reassigning"
      ocean POST v2/floating_ips/$ip/actions \
        type=assign "droplet_id=$DROPLET_ID" \
        || fatal "Couldn't assign floating ip to myself"
    fi
    sleep 600
  done
}

main "$@"