refactor: Revise check-for-changes.sh (#2615)

- Inline docs for `check-for-changes.sh` have been shuffled around and revised a bit.
- Change processing extracted from the main change detection loop method to their own methods:
   - `_get_changed_files()` - Clarifies what is going on (and how) without having to look it up. To reduce noise in the main logic loop, extracted to a separate method.
   - `_postfix_dovecot_changes()` - The bulk of change processing was moved to this method. I've added conditionals to only run relevant logic.
   - `_ssl_changes()` - Just shifted, no logic changed. `REGEX_NEVER_MATCH` and `ACME_CERT_DIR` vars scope set to `local`.

target/scripts/check-for-changes.sh

@@ -7,19 +7,18 @@
 # shellcheck source=./helpers/index.sh
 source /usr/local/bin/helpers/index.sh
 
-# This script requires some environment variables to be properly set. This
+_log_with_date 'debug' 'Starting changedetector'
-# includes POSTMASTER_ADDRESS (for alias (re-)generation), HOSTNAME and
+
-# DOMAINNAME (in ssl.sh).
+# ATTENTION: Do not remove!
+# This script requires some environment variables to be properly set.
+# POSTMASTER_ADDRESS (for helpers/alias.sh) is read from /etc/dms-settings
 # shellcheck source=/dev/null
 source /etc/dms-settings
 
-_log_with_date 'debug' 'Starting changedetector'
+# HOSTNAME and DOMAINNAME are used by helpers/ssl.sh and _monitored_files_checksums
-
+# These are not stored in /etc/dms-settings
-# TODO in the future, when we do not use HOSTNAME but DMS_HOSTNAME everywhere,
+# TODO: It is planned to stop overriding HOSTNAME and replace that
-# TODO we can delete this call as we needn't calculate the names twice
+# usage with DMS_HOSTNAME, which should remove the need to call this:
-# ATTENTION: Do not remove!
-#            This script requies HOSTNAME and DOMAINNAME
-#            to be properly set.
 _obtain_hostname_and_domainname
 
 # verify checksum file exists; must be prepared by start-mailserver.sh
@@ -28,8 +27,6 @@ then
   _exit_with_error "'${CHKSUM_FILE}' is missing" 0
 fi
 
-REGEX_NEVER_MATCH="(?\!)"
-
 _log_with_date 'trace' "Using postmaster address '${POSTMASTER_ADDRESS}'"
 
 # Change detection delayed during startup to avoid conflicting writes
@@ -51,12 +48,95 @@ function _check_for_changes
   then
     _log_with_date 'info' 'Change detected'
     _create_lock # Shared config safety lock
-    local CHANGED
-    CHANGED=$(grep -Fxvf "${CHKSUM_FILE}" "${CHKSUM_FILE}.new" | sed 's/^[^ ]\+  //')
 
-    # TODO Perform updates below conditionally too
+    local CHANGED
+    CHANGED=$(_get_changed_files "${CHKSUM_FILE}" "${CHKSUM_FILE}.new")
+
+    # Handle any changes
+    _ssl_changes
+    _postfix_dovecot_changes
+
+    # While some config changes may be properly applied by Postfix or Dovecot
+    # via their 'reload' commands; some may require restarting?:
+    _log_with_date 'debug' 'Restarting services due to detected changes'
+    supervisorctl restart postfix
+    [[ ${SMTP_ONLY} -ne 1 ]] && supervisorctl restart dovecot
+
+    _remove_lock
+    _log_with_date 'debug' 'Completed handling of detected change'
+  fi
+
+  # mark changes as applied
+  mv "${CHKSUM_FILE}.new" "${CHKSUM_FILE}"
+}
+
+function _get_changed_files
+{
+  local CHKSUM_CURRENT=${1}
+  local CHKSUM_NEW=${2}
+
+  # Diff the two files for lines that don't match or differ from lines in CHKSUM_FILE
+  # grep -Fxvf
+  #   -f use CHKSUM_FILE lines as input patterns to match for
+  #   -F The patterns to match are treated as strings only, not treated as regex syntax
+  #   -x (match whole lines only)
+  #   -v invert the matching so only non-matches are output
+  # Extract file paths by truncating the matched content hash and white-space from lines:
+  # sed -r 's/^\S+[[:space:]]+//'
+  grep -Fxvf "${CHKSUM_CURRENT}" "${CHKSUM_NEW}" | sed -r 's/^\S+[[:space:]]+//'
+}
+
 # Also note that changes are performed in place and are not atomic
 # We should fix that and write to temporary files, stop, swap and start
+function _postfix_dovecot_changes
+{
+  local DMS_DIR=/tmp/docker-mailserver
+
+  # Regenerate accounts via `helpers/accounts.sh`:
+  # - dovecot-quotas.cf used by _create_accounts + _create_dovecot_alias_dummy_accounts
+  # - postfix-virtual.cf used by _create_dovecot_alias_dummy_accounts (only when ENABLE_QUOTAS=1)
+  if [[ ${CHANGED} =~ ${DMS_DIR}/postfix-accounts.cf ]] \
+  || [[ ${CHANGED} =~ ${DMS_DIR}/postfix-virtual.cf  ]] \
+  || [[ ${CHANGED} =~ ${DMS_DIR}/postfix-aliases.cf  ]] \
+  || [[ ${CHANGED} =~ ${DMS_DIR}/dovecot-quotas.cf   ]] \
+  || [[ ${CHANGED} =~ ${DMS_DIR}/dovecot-masters.cf  ]]
+  then
+    [[ ${SMTP_ONLY} -ne 1 ]] && _create_accounts
+  fi
+
+  # Regenerate relay config via `helpers/relay.sh`:
+  # - postfix-sasl-password.cf used by _relayhost_sasl
+  # - _populate_relayhost_map relies on:
+  #   - postfix-relaymap.cf
+  #   - postfix-accounts.cf + postfix-virtual.cf (both will be dropped in future)
+  if [[ ${CHANGED} =~ ${DMS_DIR}/postfix-accounts.cf      ]] \
+  || [[ ${CHANGED} =~ ${DMS_DIR}/postfix-virtual.cf       ]] \
+  || [[ ${CHANGED} =~ ${DMS_DIR}/postfix-relaymap.cf      ]] \
+  || [[ ${CHANGED} =~ ${DMS_DIR}/postfix-sasl-password.cf ]]
+  then
+    _rebuild_relayhost
+  fi
+
+  # Regenerate system + virtual account aliases via `helpers/aliases.sh`:
+  [[ ${CHANGED} =~ ${DMS_DIR}/postfix-virtual.cf ]] && _handle_postfix_virtual_config
+  [[ ${CHANGED} =~ ${DMS_DIR}/postfix-regexp.cf  ]] && _handle_postfix_regexp_config
+  [[ ${CHANGED} =~ ${DMS_DIR}/postfix-aliases.cf ]] && _handle_postfix_aliases_config
+
+  # Regenerate `/etc/postfix/vhost` (managed mail domains) via `helpers/postfix.sh`:
+  if [[ ${CHANGED} =~ ${DMS_DIR}/postfix-accounts.cf ]] \
+  || [[ ${CHANGED} =~ ${DMS_DIR}/postfix-virtual.cf  ]]
+  then
+    _create_postfix_vhost
+  fi
+
+  # Legacy workaround handled here, only seems necessary for _create_accounts:
+  # - `helpers/accounts.sh` logic creates folders/files with wrong ownership.
+  _chown_var_mail_if_necessary
+}
+
+function _ssl_changes
+{
+  local REGEX_NEVER_MATCH='(?\!)'
 
   # _setup_ssl is required for:
   # manual - copy to internal DMS_TLS_PATH (/etc/dms/tls) that Postfix and Dovecot are configured to use.
@@ -82,7 +162,7 @@ function _check_for_changes
     _setup_ssl
 
     # Prevent an unnecessary change detection from the newly extracted cert files by updating their hashes in advance:
-      local CERT_DOMAIN
+    local CERT_DOMAIN ACME_CERT_DIR
     CERT_DOMAIN=$(_find_letsencrypt_domain)
     ACME_CERT_DIR="/etc/letsencrypt/live/${CERT_DOMAIN}"
 
@@ -92,37 +172,6 @@ function _check_for_changes
 
   # If monitored certificate files in /etc/letsencrypt/live have changed and no `acme.json` is in use,
   # They presently have no special handling other than to trigger a change that will restart Postfix/Dovecot.
-
-    # regenerate postfix accounts
-    [[ ${SMTP_ONLY} -ne 1 ]] && _create_accounts
-
-    _rebuild_relayhost
-
-    # regenerate postix aliases
-    _create_aliases
-
-    # regenerate /etc/postfix/vhost
-    # NOTE: If later adding support for LDAP with change detection and this method is called,
-    # be sure to mimic `setup-stack.sh:_setup_ldap` which appends to `/tmp/vhost.tmp`.
-    _create_postfix_vhost
-
-    # Legacy workaround handled here, only seems necessary for _create_accounts:
-    # - `helpers/accounts.sh` logic creates folders/files with wrong ownership.
-    _chown_var_mail_if_necessary
-
-    _log_with_date 'debug' 'Restarting services due to detected changes'
-
-    supervisorctl restart postfix
-
-    # prevent restart of dovecot when smtp_only=1
-    [[ ${SMTP_ONLY} -ne 1 ]] && supervisorctl restart dovecot
-
-    _remove_lock
-    _log_with_date 'debug' 'Completed handling of detected change'
-  fi
-
-  # mark changes as applied
-  mv "${CHKSUM_FILE}.new" "${CHKSUM_FILE}"
 }
 
 while true

target/scripts/helpers/aliases.sh

@@ -9,7 +9,6 @@
 function _handle_postfix_virtual_config
 {
   : >/etc/postfix/virtual
-  : >/etc/postfix/regexp
 
   local DATABASE_VIRTUAL=/tmp/docker-mailserver/postfix-virtual.cf
 
@@ -29,6 +28,8 @@ function _handle_postfix_virtual_config
 
 function _handle_postfix_regexp_config
 {
+  : >/etc/postfix/regexp
+
   if [[ -f /tmp/docker-mailserver/postfix-regexp.cf ]]
   then
     _log 'trace' "Adding regexp alias file postfix-regexp.cf"