Add reverse_lookup_enable configuration support

Dockerfile

@@ -29,6 +29,7 @@ ENV XFERLOG_STD_FORMAT NO
 ENV LOG_STDOUT **Boolean**
 ENV FILE_OPEN_MODE 0666
 ENV LOCAL_UMASK 077
+ENV REVERSE_LOOKUP_ENABLE YES
 
 COPY vsftpd.conf /etc/vsftpd/
 COPY vsftpd_virtual /etc/pam.d/

README.md

@@ -118,6 +118,13 @@ This image uses environment variables to allow the configuration of some paramet
 
 ----
 
+* Variable name: `REVERSE_LOOKUP_ENABLE`
+* Default value: YES.
+* Accepted values: YES or NO.
+* Description: Set to NO if you want to avoid performance issues where a name server doesn't respond to a reverse lookup.
+
+----
+
 Exposed ports and volumes
 ----
 

run-vsftpd.sh

@@ -37,6 +37,7 @@ echo "pasv_enable=${PASV_ENABLE}" >> /etc/vsftpd/vsftpd.conf
 echo "file_open_mode=${FILE_OPEN_MODE}" >> /etc/vsftpd/vsftpd.conf
 echo "local_umask=${LOCAL_UMASK}" >> /etc/vsftpd/vsftpd.conf
 echo "xferlog_std_format=${XFERLOG_STD_FORMAT}" >> /etc/vsftpd/vsftpd.conf
+echo "reverse_lookup_enable=${REVERSE_LOOKUP_ENABLE}" >> /etc/vsftpd/vsftpd.conf
 
 # Get log file path
 export LOG_FILE=`grep xferlog_file /etc/vsftpd/vsftpd.conf|cut -d= -f2`

vsftpd.conf

@@ -47,3 +47,5 @@ ftp_data_port=20
 
 ## Disable seccomp filter sanboxing
 seccomp_sandbox=NO
+
+### Variables set at container runtime