Option to disable full text search (lucene)

This is a workaround for the bug in issue #751

core/dovecot/conf/dovecot.conf

@@ -7,6 +7,7 @@ postmaster_address = {{ POSTMASTER }}@{{ DOMAIN }}
 hostname = {{ HOSTNAMES.split(",")[0] }}
 submission_host = {{ FRONT_ADDRESS }}
 
+{% if DISABLE_FTS_LUCENE != 'true' %}
 ###############
 # Full-text search
 ###############
@@ -20,6 +21,7 @@ plugin {
 
   fts_lucene = whitespace_chars=@.
 }
+{% endif %}
 
 ###############
 # Mailboxes

docs/compose/.env

@@ -3,6 +3,10 @@
 # these few settings must however be configured before starting the mail
 # server and require a restart upon change.
 
+# Set this to `true` to disable full text search by lucene (value: true, false)
+# This is a workaround for the bug in issue #751 (indexer-worker crashes)
+DISABLE_FTS_LUCENE=false
+
 ###################################
 # Common configuration variables
 ###################################