Hook script for dehydrated (Let's Encrypt)

de-hook.sh

#!/bin/bash
# -- de-hook.sh ----------------------------------------------------------------
#
# This program comes with no warranty. Use at your own risk.
# You have been warned. (That said, it works well for me :)
#
# This script is for reloading Nginx whenever [dehydrated] creates or renews the
# certificate file(s). This is meant to be used as a hook wherein `dehydrated`
# exports $BASEDIR automatically.
#
# Written in a way to pass the [ShellCheck] test B)
#
# It’s also highly readable and serves as an example/template when composing
# new scripts.
#
# Copyright (c) 2017 ed.o
# include 'MIT-License.txt'
#
#
# [dehydrated]: https://dehydrated.de
# [ShellCheck]: http://www.shellcheck.net
#
# ------------------------------------------------------------------------------
# Report undefined variables
shopt -s -o nounset

# Default $BASEDIR; automatically exported by `dehydrated`
# Uncomment or change only when testing.
#BASEDIR=/etc/dehydrated

# Name of this script
declare -rx ME=${0##*/}

DATE_TODAY=$(date +%F)

DOMAINS=$(cat "$BASEDIR/domains.txt")

# How I function
display_usage() {

    cat <<EOE

    This script is meant be run as a hook by dehydrated.

    Add to ${BASEDIR}/config or as a parameter when running dehydrated e.g.,

        $ dehydrated --cron --hook ${ME}

EOE

    exit 0

}

get_mod_date() {

    local path_to_file="$1"
    local real_target

    real_target=$(realpath "$path_to_file")

    date --reference "$real_target" +%F

}

reload_if_new_cert() {

    local pem_file_mod_date

    for domain in $DOMAINS
    do
        pem_file_mod_date=$(get_mod_date "$BASEDIR/certs/$domain/fullchain.pem")

        [[ "$pem_file_mod_date" == "$DATE_TODAY" ]] \
            && /sbin/service nginx reload

    done

}

# This is where the party starts ;)
main() {

    while getopts ":h" opt; do
        case $opt in
            h|*)
                display_usage
            ;;
        esac
    done

    reload_if_new_cert

}

main "$@"