pi-hole/advanced/Scripts/updatecheck.sh

#!/usr/bin/env bash
# Pi-hole: A black hole for Internet advertisements
# (c) 2017 Pi-hole, LLC (https://pi-hole.net)
# Network-wide ad blocking via your own hardware.
#
# Checks for updates via GitHub
#
# This file is copyright under the latest version of the EUPL.
# Please see LICENSE file for your rights under this license.

# Credit: https://stackoverflow.com/a/46324904
function json_extract() {
  local key=$1
  local json=$2

  local string_regex='"([^"\]|\\.)*"'
  local number_regex='-?(0|[1-9][0-9]*)(\.[0-9]+)?([eE][+-]?[0-9]+)?'
  local value_regex="${string_regex}|${number_regex}|true|false|null"
  local pair_regex="\"${key}\"[[:space:]]*:[[:space:]]*(${value_regex})"

  if [[ ${json} =~ ${pair_regex} ]]; then
    echo $(sed 's/^"\|"$//g' <<< "${BASH_REMATCH[1]}")
  else
    return 1
  fi
}

GITHUB_CORE_VERSION="$(json_extract tag_name "$(curl -q 'https://api.github.com/repos/pi-hole/pi-hole/releases/latest' 2> /dev/null)")"
GITHUB_WEB_VERSION="$(json_extract tag_name "$(curl -q 'https://api.github.com/repos/pi-hole/AdminLTE/releases/latest' 2> /dev/null)")"
GITHUB_FTL_VERSION="$(json_extract tag_name "$(curl -q 'https://api.github.com/repos/pi-hole/FTL/releases/latest' 2> /dev/null)")"

echo "${GITHUB_CORE_VERSION} ${GITHUB_WEB_VERSION} ${GITHUB_FTL_VERSION}" > "/etc/pihole/GitHubVersions"

function get_local_branch() {
  # Return active branch
  cd "${1}" 2> /dev/null || return 1
  git rev-parse --abbrev-ref HEAD || return 1
}

CORE_BRANCH="$(get_local_branch /etc/.pihole)"
WEB_BRANCH="$(get_local_branch /var/www/html/admin)"
#FTL_BRANCH="$(pihole-FTL branch)"
# Don't store FTL branch until the next release of FTL which
# supports returning the branch in an easy way
FTL_BRANCH="XXX"

echo "${CORE_BRANCH} ${WEB_BRANCH} ${FTL_BRANCH}" > "/etc/pihole/localbranches"

function get_local_version() {
  # Return active branch
  cd "${1}" 2> /dev/null || return 1
  git describe --long --dirty --tags || return 1
}

CORE_VERSION="$(get_local_version /etc/.pihole)"
WEB_VERSION="$(get_local_version /var/www/html/admin)"
FTL_VERSION="$(pihole-FTL version)"

echo "${CORE_VERSION} ${WEB_VERSION} ${FTL_VERSION}" > "/etc/pihole/localversions"