misc: final Rspamd adjustments for v13 (#3599)

* outsource Rspamd ENVs into explicit helper

This will allow us to uniformly source the helper and get the values
from everywhere consistently. This is more than desirable since we will
be using these values not only for the Rspamd setup, but also for DKIM
management and during change-detection.

* integrate Rspamd into changedetection

We outsource one more function to reside in the helper script for Rspamd
so that we can call this function from the Rspamd setup and from the
changedetection functionality too.

* realize deprecation of old commands file for Rspamd

THIS IS A BREAKING CHANGE!

This change realizes the log message: "Using old file location now
(deprecated) - this will prevent startup in v13.0.0" Startup will now
fail.

* added '--force' option to Rspamd DKIM script

* use new helper to get ENVs for Rspamd in DKIM script

* remove the need for linking directories

This was unnecessary, as explained in
https://github.com/docker-mailserver/docker-mailserver/pull/3597#discussion_r1369413599

* Apply suggestions from code review

review by @polarathene

* apply more review feedback from @polarathene

- <https://github.com/docker-mailserver/docker-mailserver/pull/3599#discussion_r1370885519>
- <https://github.com/docker-mailserver/docker-mailserver/pull/3599#discussion_r1370904201>

* update documentation

---------

Co-authored-by: Brennan Kinney <5098581+polarathene@users.noreply.github.com>

target/scripts/check-for-changes.sh

@@ -21,6 +21,10 @@ source /etc/dms-settings
 # usage with DMS_HOSTNAME, which should remove the need to call this:
 _obtain_hostname_and_domainname
 
+# This is a helper to properly set all Rspamd-related environment variables
+# correctly and in one place.
+_rspamd_get_envs
+
 # verify checksum file exists; must be prepared by start-mailserver.sh
 if [[ ! -f ${CHKSUM_FILE} ]]; then
   _exit_with_error "'${CHKSUM_FILE}' is missing" 0
@@ -49,6 +53,7 @@ function _check_for_changes() {
     # Handle any changes
     _ssl_changes
     _postfix_dovecot_changes
+    _rspamd_changes
 
     _log_with_date 'debug' 'Reloading services due to detected changes'
 
@@ -174,6 +179,33 @@ function _ssl_changes() {
   # They presently have no special handling other than to trigger a change that will restart Postfix/Dovecot.
 }
 
+function _rspamd_changes() {
+  # RSPAMD_DMS_D='/tmp/docker-mailserver/rspamd'
+  if [[ ${CHANGED} =~ ${RSPAMD_DMS_D}/.* ]]; then
+
+    # "${RSPAMD_DMS_D}/override.d"
+    if [[ ${CHANGED} =~ ${RSPAMD_DMS_OVERRIDE_D}/.* ]]; then
+      _log_with_date 'trace' 'Rspamd - Copying configuration overrides'
+      rm "${RSPAMD_OVERRIDE_D}"/*
+      cp "${RSPAMD_DMS_OVERRIDE_D}"/* "${RSPAMD_OVERRIDE_D}"
+    fi
+
+    # "${RSPAMD_DMS_D}/custom-commands.conf"
+    if [[ ${CHANGED} =~ ${RSPAMD_DMS_CUSTOM_COMMANDS_F} ]]; then
+      _log_with_date 'trace' 'Rspamd - Generating new configuration from custom commands'
+      _rspamd_handle_user_modules_adjustments
+    fi
+
+    # "${RSPAMD_DMS_D}/dkim"
+    if [[ ${CHANGED} =~ ${RSPAMD_DMS_DKIM_D} ]]; then
+      _log_with_date 'trace' 'Rspamd - DKIM files updated'
+    fi
+
+    _log_with_date 'debug' 'Rspamd configuration has changed - restarting service'
+    supervisorctl restart rspamd
+  fi
+}
+
 while true; do
   _check_for_changes
   sleep 2