Fixing the default value for MM_HOSTNAME (#454)

core/docker-entrypoint.sh

@@ -27,10 +27,10 @@ function wait_for_mysql () {
 echo "# This file is autogenerated at container startup." > /etc/mailman.cfg
 
 # Check if $MM_HOSTNAME is set, if not, set it to the value returned by
-# `hostname` command to set it to whatever hostname is assigned to the
+# `hostname -i` command to set it to whatever IP address is assigned to the
 # container.
 if [[ ! -v MM_HOSTNAME ]]; then
-	export MM_HOSTNAME=`hostname`
+	export MM_HOSTNAME=`hostname -i`
 fi
 
 # SMTP_HOST defaults to the gateway