Merge branch '22-allow-setting-egress' into 'master'

#22:  Allow setting port for smtp egress when used as secondary

See merge request ix.ai/smtp!17

README.md

@@ -25,6 +25,8 @@ The container accepts `OTHER_HOSTNAMES` environment variable which will set the
 
 The container accepts `NET_DEV` environment variable to override the default `eth0` interface for retrieving the IP address for relay networks.
 
+The container accepts `SMTPPORTOUT`environment variable to override the default port of 25 for connecting to the primary mailserver when used as secondary(eg. setting RELAY_DOMAINS)
+
 ## Below are scenarios for using this container
 
 ### As SMTP Server

entrypoint.sh

@@ -38,6 +38,11 @@ if [ "$MAILNAME" ]; then
 	echo "$MAILNAME" > /etc/mailname
 fi
 
+if [ "${SMTPPORTOUT}" ]; then
+	awk -v port_var="${SMTPPORTOUT}" '/remote_smtp:/{ n=NR+2 } NR==n{ $0="  driver = smtp\n  port = "port_var }1' /etc/exim4/exim4.conf.template > /etc/exim4/exim4.conf.temp
+	mv /etc/exim4/exim4.conf.temp /etc/exim4/exim4.conf.template
+fi
+
 if [ "$KEY_PATH" ] && [ "$CERTIFICATE_PATH" ]; then
 	if [ "$MAILNAME" ]; then
 	  echo "MAIN_TLS_ENABLE = yes" >>  /etc/exim4/exim4.conf.localmacros