allow a custom dkim selector

management/dns_update.py

@@ -291,7 +291,7 @@ def build_zone(domain, domain_properties, additional_records, env, is_zone=True)
 
 		# Append the DKIM TXT record to the zone as generated by OpenDKIM.
 		# Skip if the user has set a DKIM record already.
-		opendkim_record_file = os.path.join(env['STORAGE_ROOT'], 'mail/dkim/mail.txt')
+		opendkim_record_file = os.path.join(env['STORAGE_ROOT'], 'mail/dkim/' + env['DKIM_SELECTOR'] + '.txt')
 		with open(opendkim_record_file, encoding="utf-8") as orf:
 			m = re.match(r'(\S+)\s+IN\s+TXT\s+\( ((?:"[^"]+"\s+)+)\)', orf.read(), re.S)
 			val = "".join(re.findall(r'"([^"]+)"', m.group(2)))
@@ -752,12 +752,13 @@ def write_opendkim_tables(domains, env):
 	# Append a record to OpenDKIM's KeyTable and SigningTable for each domain
 	# that we send mail from (zones and all subdomains).
 
-	opendkim_key_file = os.path.join(env['STORAGE_ROOT'], 'mail/dkim/mail.private')
+	opendkim_key_file = os.path.join(env['STORAGE_ROOT'], 'mail/dkim/' + env['DKIM_SELECTOR'] + '.private')
 
 	if not os.path.exists(opendkim_key_file):
 		# Looks like OpenDKIM is not installed.
 		return False
 
+	selector=env['DKIM_SELECTOR']
 	config = {
 		# The SigningTable maps email addresses to a key in the KeyTable that
 		# specifies signing information for matching email addresses. Here we
@@ -777,7 +778,7 @@ def write_opendkim_tables(domains, env):
 		# signing domain must match the sender's From: domain.
 		"KeyTable":
 			"".join(
-				f"{domain} {domain}:mail:{opendkim_key_file}\n"
+				f"{domain} {domain}:{selector}:{opendkim_key_file}\n"
 				for domain in domains
 			),
 	}

setup/dkim.sh

@@ -52,8 +52,8 @@ fi
 # A 1024-bit key is seen as a minimum standard by several providers
 # such as Google. But they and others use a 2048 bit key, so we'll
 # do the same. Keys beyond 2048 bits may exceed DNS record limits.
-if [ ! -f "$STORAGE_ROOT/mail/dkim/mail.private" ]; then
-	opendkim-genkey -b 2048 -r -s mail -D "$STORAGE_ROOT/mail/dkim"
+if [ ! -f "$STORAGE_ROOT/mail/dkim/$DKIM_SELECTOR.private" ]; then
+	opendkim-genkey -b 2048 -r -s $DKIM_SELECTOR -D $STORAGE_ROOT/mail/dkim
 fi
 
 # Ensure files are owned by the opendkim user and are private otherwise.

setup/start.sh

@@ -111,6 +111,7 @@ PUBLIC_IPV6=$PUBLIC_IPV6
 PRIVATE_IP=$PRIVATE_IP
 PRIVATE_IPV6=$PRIVATE_IPV6
 MTA_STS_MODE=${DEFAULT_MTA_STS_MODE:-enforce}
+DKIM_SELECTOR=${DEFAULT_DKIM_SELECTOR:-mail}
 EOF
 
 # Start service configuration.