gluetun-mullvad-rotate: Automate randomly choosing a Mullvad VPN server based on SERVER_CITIES variable in docker_compose.yml

gluetun-mullvad-rotate

#!/bin/bash
# Depends: jq (https://stedolan.github.io/jq/)

default_compose="/docker/compose/gluetun/docker-compose.yml"
compose="${1:-$default_compose}"
relays_url="https://api.mullvad.net/www/relays/all/"

fail() { printf "%s: %s\n" "$0" "$*"; exit 1; }

read_var() {
  declare -g $1="$(sed -n '/^\s*- '$1'=/{s///;p}' "$compose")"
  [[ -z "${!1}" ]] && fail "Couldn't read '$1' value from '$compose'."
}

extract_hostnames() {
  jq -r \
    --arg cities "$SERVER_CITIES" \
    --arg vpntype "$VPN_TYPE" \
    '
      . as $mullvad

      | $cities | split(",")
      | [ .[] | sub(" (?<state>[A-Z][A-Z]$)"; ", " + .state) ]
      | . as $cities

      | $mullvad | .[]
      | select(.active==true)
      | select(.city_name as $c | any($cities[]; . == $c))
      | select(.type == $vpntype)
      | .hostname
    '
}

type jq &>/dev/null ||
  fail "jq not installed or not in PATH (https://stedolan.github.io/jq/)"

read_var VPN_TYPE
read_var SERVER_CITIES
read_var SERVER_HOSTNAMES

servers=$(curl -s "$relays_url" | extract_hostnames)
servers=$(grep -v "^$SERVER_HOSTNAMES$" <<<$servers) # Don't pick current server
[[ -z "$servers" ]] &&
  fail "No candidate servers returned for cities '$SERVER_CITIES'."

server="$(shuf -n1 <<< "$servers")"
printf "New server: %s\tOld server: %s\n" "$server" "$SERVER_HOSTNAMES"

sed -i~ "s/^\(\s*- SERVER_HOSTNAMES\)=.*/\1=$server/" "$compose" &&
  rm -f "$compose~"

docker-compose --file "$compose" pull
docker-compose --file "$compose" up -d