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@loganlinn
Created June 19, 2020 07:43
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BASH script for dynamic DNS for domain managed with Digital Ocean
#!/usr/bin/env bash
# Exit on error. Append "|| true" if you expect an error.
set -o errexit
# Exit on error inside any functions or subshells.
set -o errtrace
# Do not allow use of undefined vars. Use ${VAR:-} to use an undefined VAR
set -o nounset
# Catch the error in case mysqldump fails (but gzip succeeds) in `mysqldump |gzip`
set -o pipefail
# Turn on traces, useful while debugging but commented out by default
# set -o xtrace
if [[ "${BASH_SOURCE[0]}" != "${0}" ]]; then
__i_am_main_script="0" # false
if [[ "${__usage+x}" ]]; then
if [[ "${BASH_SOURCE[1]}" = "${0}" ]]; then
__i_am_main_script="1" # true
fi
__b3bp_external_usage="true"
__b3bp_tmp_source_idx=1
fi
else
__i_am_main_script="1" # true
[[ "${__usage+x}" ]] && unset -v __usage
[[ "${__helptext+x}" ]] && unset -v __helptext
fi
# Set magic variables for current file, directory, os, etc.
__dir="$(cd "$(dirname "${BASH_SOURCE[${__b3bp_tmp_source_idx:-0}]}")" && pwd)"
__file="${__dir}/$(basename "${BASH_SOURCE[${__b3bp_tmp_source_idx:-0}]}")"
__base="$(basename "${__file}" .sh)"
# shellcheck disable=SC2034,SC2015
__invocation="$(printf %q "${__file}")$( (($#)) && printf ' %q' "$@" || true)"
# Define the environment variables (and their defaults) that this script depends on
LOG_LEVEL="${LOG_LEVEL:-6}" # 7 = debug -> 0 = emergency
NO_COLOR="${NO_COLOR:-}" # true = disable color. otherwise autodetected
DOMAIN="${DOMAIN:-llinn.dev}"
INTERNAL_SUBDOMAIN="${INTERNAL_SUBDOMAIN:-internal}"
### Functions
##############################################################################
function __b3bp_log () {
local log_level="${1}"
shift
# shellcheck disable=SC2034
local color_debug="\\x1b[35m"
# shellcheck disable=SC2034
local color_info="\\x1b[32m"
# shellcheck disable=SC2034
local color_notice="\\x1b[34m"
# shellcheck disable=SC2034
local color_warning="\\x1b[33m"
# shellcheck disable=SC2034
local color_error="\\x1b[31m"
# shellcheck disable=SC2034
local color_critical="\\x1b[1;31m"
# shellcheck disable=SC2034
local color_alert="\\x1b[1;37;41m"
# shellcheck disable=SC2034
local color_emergency="\\x1b[1;4;5;37;41m"
local colorvar="color_${log_level}"
local color="${!colorvar:-${color_error}}"
local color_reset="\\x1b[0m"
if [[ "${NO_COLOR:-}" = "true" ]] || { [[ "${TERM:-}" != "xterm"* ]] && [[ "${TERM:-}" != "screen"* ]]; } || [[ ! -t 2 ]]; then
if [[ "${NO_COLOR:-}" != "false" ]]; then
# Don't use colors on pipes or non-recognized terminals
color=""; color_reset=""
fi
fi
# all remaining arguments are to be printed
local log_line=""
while IFS=$'\n' read -r log_line; do
echo -e "$(date -u +"%Y-%m-%d %H:%M:%S UTC") ${color}$(printf "[%9s]" "${log_level}")${color_reset} ${log_line}" 1>&2
done <<< "${@:-}"
}
function emergency () { __b3bp_log emergency "${@}"; exit 1; }
function alert () { [[ "${LOG_LEVEL:-0}" -ge 1 ]] && __b3bp_log alert "${@}"; true; }
function critical () { [[ "${LOG_LEVEL:-0}" -ge 2 ]] && __b3bp_log critical "${@}"; true; }
function error () { [[ "${LOG_LEVEL:-0}" -ge 3 ]] && __b3bp_log error "${@}"; true; }
function warning () { [[ "${LOG_LEVEL:-0}" -ge 4 ]] && __b3bp_log warning "${@}"; true; }
function notice () { [[ "${LOG_LEVEL:-0}" -ge 5 ]] && __b3bp_log notice "${@}"; true; }
function info () { [[ "${LOG_LEVEL:-0}" -ge 6 ]] && __b3bp_log info "${@}"; true; }
function debug () { [[ "${LOG_LEVEL:-0}" -ge 7 ]] && __b3bp_log debug "${@}"; true; }
function help () {
echo "" 1>&2
echo " ${*}" 1>&2
echo "" 1>&2
echo " ${__usage:-No usage available}" 1>&2
echo "" 1>&2
if [[ "${__helptext:-}" ]]; then
echo " ${__helptext}" 1>&2
echo "" 1>&2
fi
exit 1
}
### Parse commandline options
##############################################################################
# Commandline options. This defines the usage page, and is used to parse cli
# opts & defaults from. The parsing is unforgiving so be precise in your syntax
# - A short option must be preset for every long option; but every short option
# need not have a long option
# - `--` is respected as the separator between options and arguments
# - We do not bash-expand defaults, so setting '~/app' as a default will not resolve to ${HOME}.
# you can use bash variables to work around this (so use ${HOME} instead)
# shellcheck disable=SC2015
[[ "${__usage+x}" ]] || read -r -d '' __usage <<-'EOF' || true # exits non-zero when EOF encountered
-v Enable verbose mode, print script as it is executed
-d --debug Enables debug mode
-h --help This page
-n --no-color Disable color output
EOF
# shellcheck disable=SC2015
[[ "${__helptext+x}" ]] || read -r -d '' __helptext <<-'EOF' || true # exits non-zero when EOF encountered
Creates or updates DNS record(s) in Digital Ocean for this host
EOF
# Translate usage string -> getopts arguments, and set $arg_<flag> defaults
while read -r __b3bp_tmp_line; do
if [[ "${__b3bp_tmp_line}" =~ ^- ]]; then
# fetch single character version of option string
__b3bp_tmp_opt="${__b3bp_tmp_line%% *}"
__b3bp_tmp_opt="${__b3bp_tmp_opt:1}"
# fetch long version if present
__b3bp_tmp_long_opt=""
if [[ "${__b3bp_tmp_line}" = *"--"* ]]; then
__b3bp_tmp_long_opt="${__b3bp_tmp_line#*--}"
__b3bp_tmp_long_opt="${__b3bp_tmp_long_opt%% *}"
fi
# map opt long name to+from opt short name
printf -v "__b3bp_tmp_opt_long2short_${__b3bp_tmp_long_opt//-/_}" '%s' "${__b3bp_tmp_opt}"
printf -v "__b3bp_tmp_opt_short2long_${__b3bp_tmp_opt}" '%s' "${__b3bp_tmp_long_opt//-/_}"
# check if option takes an argument
if [[ "${__b3bp_tmp_line}" =~ \[.*\] ]]; then
__b3bp_tmp_opt="${__b3bp_tmp_opt}:" # add : if opt has arg
__b3bp_tmp_init="" # it has an arg. init with ""
printf -v "__b3bp_tmp_has_arg_${__b3bp_tmp_opt:0:1}" '%s' "1"
elif [[ "${__b3bp_tmp_line}" =~ \{.*\} ]]; then
__b3bp_tmp_opt="${__b3bp_tmp_opt}:" # add : if opt has arg
__b3bp_tmp_init="" # it has an arg. init with ""
# remember that this option requires an argument
printf -v "__b3bp_tmp_has_arg_${__b3bp_tmp_opt:0:1}" '%s' "2"
else
__b3bp_tmp_init="0" # it's a flag. init with 0
printf -v "__b3bp_tmp_has_arg_${__b3bp_tmp_opt:0:1}" '%s' "0"
fi
__b3bp_tmp_opts="${__b3bp_tmp_opts:-}${__b3bp_tmp_opt}"
if [[ "${__b3bp_tmp_line}" =~ ^Can\ be\ repeated\. ]] || [[ "${__b3bp_tmp_line}" =~ \.\ *Can\ be\ repeated\. ]]; then
# remember that this option can be repeated
printf -v "__b3bp_tmp_is_array_${__b3bp_tmp_opt:0:1}" '%s' "1"
else
printf -v "__b3bp_tmp_is_array_${__b3bp_tmp_opt:0:1}" '%s' "0"
fi
fi
[[ "${__b3bp_tmp_opt:-}" ]] || continue
if [[ "${__b3bp_tmp_line}" =~ ^Default= ]] || [[ "${__b3bp_tmp_line}" =~ \.\ *Default= ]]; then
# ignore default value if option does not have an argument
__b3bp_tmp_varname="__b3bp_tmp_has_arg_${__b3bp_tmp_opt:0:1}"
if [[ "${!__b3bp_tmp_varname}" != "0" ]]; then
# take default
__b3bp_tmp_init="${__b3bp_tmp_line##*Default=}"
# strip double quotes from default argument
__b3bp_tmp_re='^"(.*)"$'
if [[ "${__b3bp_tmp_init}" =~ ${__b3bp_tmp_re} ]]; then
__b3bp_tmp_init="${BASH_REMATCH[1]}"
else
# strip single quotes from default argument
__b3bp_tmp_re="^'(.*)'$"
if [[ "${__b3bp_tmp_init}" =~ ${__b3bp_tmp_re} ]]; then
__b3bp_tmp_init="${BASH_REMATCH[1]}"
fi
fi
fi
fi
if [[ "${__b3bp_tmp_line}" =~ ^Required\. ]] || [[ "${__b3bp_tmp_line}" =~ \.\ *Required\. ]]; then
# remember that this option requires an argument
printf -v "__b3bp_tmp_has_arg_${__b3bp_tmp_opt:0:1}" '%s' "2"
fi
# Init var with value unless it is an array / a repeatable
__b3bp_tmp_varname="__b3bp_tmp_is_array_${__b3bp_tmp_opt:0:1}"
[[ "${!__b3bp_tmp_varname}" = "0" ]] && printf -v "arg_${__b3bp_tmp_opt:0:1}" '%s' "${__b3bp_tmp_init}"
done <<< "${__usage:-}"
# run getopts only if options were specified in __usage
if [[ "${__b3bp_tmp_opts:-}" ]]; then
# Allow long options like --this
__b3bp_tmp_opts="${__b3bp_tmp_opts}-:"
# Reset in case getopts has been used previously in the shell.
OPTIND=1
# start parsing command line
set +o nounset # unexpected arguments will cause unbound variables
# to be dereferenced
# Overwrite $arg_<flag> defaults with the actual CLI options
while getopts "${__b3bp_tmp_opts}" __b3bp_tmp_opt; do
[[ "${__b3bp_tmp_opt}" = "?" ]] && help "Invalid use of script: ${*} "
if [[ "${__b3bp_tmp_opt}" = "-" ]]; then
# OPTARG is long-option-name or long-option=value
if [[ "${OPTARG}" =~ .*=.* ]]; then
# --key=value format
__b3bp_tmp_long_opt=${OPTARG/=*/}
# Set opt to the short option corresponding to the long option
__b3bp_tmp_varname="__b3bp_tmp_opt_long2short_${__b3bp_tmp_long_opt//-/_}"
printf -v "__b3bp_tmp_opt" '%s' "${!__b3bp_tmp_varname}"
OPTARG=${OPTARG#*=}
else
# --key value format
# Map long name to short version of option
__b3bp_tmp_varname="__b3bp_tmp_opt_long2short_${OPTARG//-/_}"
printf -v "__b3bp_tmp_opt" '%s' "${!__b3bp_tmp_varname}"
# Only assign OPTARG if option takes an argument
__b3bp_tmp_varname="__b3bp_tmp_has_arg_${__b3bp_tmp_opt}"
__b3bp_tmp_varvalue="${!__b3bp_tmp_varname}"
[[ "${__b3bp_tmp_varvalue}" != "0" ]] && __b3bp_tmp_varvalue="1"
printf -v "OPTARG" '%s' "${@:OPTIND:${__b3bp_tmp_varvalue}}"
# shift over the argument if argument is expected
((OPTIND+=__b3bp_tmp_varvalue))
fi
# we have set opt/OPTARG to the short value and the argument as OPTARG if it exists
fi
__b3bp_tmp_value="${OPTARG}"
__b3bp_tmp_varname="__b3bp_tmp_is_array_${__b3bp_tmp_opt:0:1}"
if [[ "${!__b3bp_tmp_varname}" != "0" ]]; then
# repeatables
# shellcheck disable=SC2016
if [[ -z "${OPTARG}" ]]; then
# repeatable flags, they increcemnt
__b3bp_tmp_varname="arg_${__b3bp_tmp_opt:0:1}"
debug "cli arg ${__b3bp_tmp_varname} = (${__b3bp_tmp_default}) -> ${!__b3bp_tmp_varname}"
__b3bp_tmp_value=$((${!__b3bp_tmp_varname} + 1))
printf -v "${__b3bp_tmp_varname}" '%s' "${__b3bp_tmp_value}"
else
# repeatable args, they get appended to an array
__b3bp_tmp_varname="arg_${__b3bp_tmp_opt:0:1}[@]"
debug "cli arg ${__b3bp_tmp_varname} append ${__b3bp_tmp_value}"
declare -a "${__b3bp_tmp_varname}"='("${!__b3bp_tmp_varname}" "${__b3bp_tmp_value}")'
fi
else
# non-repeatables
__b3bp_tmp_varname="arg_${__b3bp_tmp_opt:0:1}"
__b3bp_tmp_default="${!__b3bp_tmp_varname}"
if [[ -z "${OPTARG}" ]]; then
__b3bp_tmp_value=$((__b3bp_tmp_default + 1))
fi
printf -v "${__b3bp_tmp_varname}" '%s' "${__b3bp_tmp_value}"
debug "cli arg ${__b3bp_tmp_varname} = (${__b3bp_tmp_default}) -> ${!__b3bp_tmp_varname}"
fi
done
set -o nounset # no more unbound variable references expected
shift $((OPTIND-1))
if [[ "${1:-}" = "--" ]] ; then
shift
fi
fi
### Automatic validation of required option arguments
##############################################################################
for __b3bp_tmp_varname in ${!__b3bp_tmp_has_arg_*}; do
# validate only options which required an argument
[[ "${!__b3bp_tmp_varname}" = "2" ]] || continue
__b3bp_tmp_opt_short="${__b3bp_tmp_varname##*_}"
__b3bp_tmp_varname="arg_${__b3bp_tmp_opt_short}"
[[ "${!__b3bp_tmp_varname}" ]] && continue
__b3bp_tmp_varname="__b3bp_tmp_opt_short2long_${__b3bp_tmp_opt_short}"
printf -v "__b3bp_tmp_opt_long" '%s' "${!__b3bp_tmp_varname}"
[[ "${__b3bp_tmp_opt_long:-}" ]] && __b3bp_tmp_opt_long=" (--${__b3bp_tmp_opt_long//_/-})"
help "Option -${__b3bp_tmp_opt_short}${__b3bp_tmp_opt_long:-} requires an argument"
done
### Cleanup Environment variables
##############################################################################
for __tmp_varname in ${!__b3bp_tmp_*}; do
unset -v "${__tmp_varname}"
done
unset -v __tmp_varname
### Externally supplied __usage. Nothing else to do here
##############################################################################
if [[ "${__b3bp_external_usage:-}" = "true" ]]; then
unset -v __b3bp_external_usage
return
fi
### Signal trapping and backtracing
##############################################################################
function __b3bp_cleanup_before_exit () {
debug "Cleaning up. Done"
}
trap __b3bp_cleanup_before_exit EXIT
# requires `set -o errtrace`
__b3bp_err_report() {
local error_code=${?}
error "Error in ${__file} in function ${1} on line ${2}"
exit ${error_code}
}
# Uncomment the following line for always providing an error backtrace
# trap '__b3bp_err_report "${FUNCNAME:-.}" ${LINENO}' ERR
### Command-line argument switches (like -d for debugmode, -h for showing helppage)
##############################################################################
# debug mode
if [[ "${arg_d:?}" = "1" ]]; then
set -o xtrace
PS4='+(${BASH_SOURCE}:${LINENO}): ${FUNCNAME[0]:+${FUNCNAME[0]}(): }'
LOG_LEVEL="7"
# Enable error backtracing
trap '__b3bp_err_report "${FUNCNAME:-.}" ${LINENO}' ERR
fi
# verbose mode
if [[ "${arg_v:?}" = "1" ]]; then
set -o verbose
fi
# no color mode
if [[ "${arg_n:?}" = "1" ]]; then
NO_COLOR="true"
fi
# help mode
if [[ "${arg_h:?}" = "1" ]]; then
# Help exists with code 1
help "Help using ${0}"
fi
### Validation. Error out if the things required for your script are not present
##############################################################################
#[[ "${arg_f:-}" ]] || help "Setting a filename with -f or --file is required"
[[ "${LOG_LEVEL:-}" ]] || emergency "Cannot continue without LOG_LEVEL. "
### Runtime
##############################################################################
function doctlw () {
debug "running doctl $@"
doctl "$@"
}
function __announce_record_op () {
local op=${1}
shift
notice "${op} ${DOMAIN} ${__record_type} record: ${__record_name} -> ${__record_data}"
}
debug "OSTYPE: ${OSTYPE}"
__host_name=$(hostname -s)
__host_internal_ip=$(hostname -I | cut -d' ' -f 1)
# internal subdomain
__record_type=A
__record_data=${__host_internal_ip}
__record_name=${__host_name}.${INTERNAL_SUBDOMAIN}
info "refreshing records for FQDN: ${__record_name}.${DOMAIN}"
__record_id=$(doctl compute domain records list ${DOMAIN} --format ID,Name --no-header | awk "/${__record_name}/ { print \$1 }")
if [[ -n "${__record_id}" ]]; then
info "found record: ${__record_name}: id=${__record_id}"
__announce_record_op "update"
doctlw compute domain records update "$DOMAIN" \
--record-id "${__record_id}" \
--record-type "$__record_type" \
--record-name "$__record_name" \
--record-data "$__record_data"
else
info "record not found: ${__record_name}"
__announce_record_op "create"
doctlw compute domain records create "$DOMAIN" \
--record-type "$__record_type" \
--record-name "$__record_name" \
--record-data "$__record_data"
fi
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