How to Synchronize Directories Using Lsyncd on Ubuntu 20.04
Lsyncd is a simple and lightweight tool that allows you to mirror your local directory to another directory on the remote server. It works by continuously monitoring the specified directory for changes every few seconds and if any changes are made then they synchronized to the remote server. This tool is very useful to sync the data from a secure area to a non-secure area.
In this tutorial, we will show you how to install and use Lsyncd to synchronize local directories and remote directories.
Prerequisites
- A server running Ubuntu 20.04.
- A root password is setup on your server.
Getting Started
Before starting, it is a good idea to update your system's package to the latest version. You can update them using the following command:
apt-get update -y
apt-get upgrade -y
Once all the packages are updated, restart your system to apply the changes.
Install Lsyncd
By default, Lsyncd package is available in most Linux operating systems. You can install it by just running the following command:
apt-get install lsyncd -y
Once the Lsyncd is installed, you can verify the installed version of Lsyncd with the following command:
lsyncd --version
You should get the following output:
Version: 2.2.3
Configure Lsyncd to Synchronize Local Directories
In this section, we will configure Lsyncd to synchronize /etc/ directory to /mnt/ directory on local system.
First, create a directory for Lsyncd with the following command:
mkdir /etc/lsyncd
Next, create a new Lsyncd configuration file and define the source and destination directory that you want to sync.
nano /etc/lsyncd/lsyncd.conf.lua
Add the following lines:
settings {
logfile = "/var/log/lsyncd/lsyncd.log",
statusFile = "/var/log/lsyncd/lsyncd.status",
statusInterval = 20,
nodaemon = false
}
sync {
default.rsync,
source = "/etc/",
target = "/mnt"
}
Save and close the file when you are finished.
systemctl start lsyncd
systemctl enable lsyncd
You can also check the status of the Lsyncd service with the following command:
systemctl status lsyncd
You should see the following output:
? lsyncd.service - LSB: lsyncd daemon init script
Loaded: loaded (/etc/init.d/lsyncd; generated)
Active: active (running) since Fri 2020-05-01 03:31:20 UTC; 9s ago
Docs: man:systemd-sysv-generator(8)
Process: 36946 ExecStart=/etc/init.d/lsyncd start (code=exited, status=0/SUCCESS)
Tasks: 2 (limit: 4620)
Memory: 12.5M
CGroup: /system.slice/lsyncd.service
??36921 /usr/bin/lsyncd -pidfile /var/run/lsyncd.pid /etc/lsyncd/lsyncd.conf.lua
??36952 /usr/bin/lsyncd -pidfile /var/run/lsyncd.pid /etc/lsyncd/lsyncd.conf.lua
May 01 03:31:20 ubuntu20 systemd[1]: lsyncd.service: Succeeded.
May 01 03:31:20 ubuntu20 systemd[1]: Stopped LSB: lsyncd daemon init script.
May 01 03:31:20 ubuntu20 systemd[1]: Starting LSB: lsyncd daemon init script...
May 01 03:31:20 ubuntu20 lsyncd[36946]: * Starting synchronization daemon lsyncd
May 01 03:31:20 ubuntu20 lsyncd[36951]: 03:31:20 Normal: --- Startup, daemonizing ---
May 01 03:31:20 ubuntu20 lsyncd[36946]: ...done.
May 01 03:31:20 ubuntu20 systemd[1]: Started LSB: lsyncd daemon init script.
You can check the Lsyncd log file for more details as shown below:
tail -f /var/log/lsyncd/lsyncd.log
You should see the following output:
/lsyncd/lsyncd.conf.lua Fri May 1 03:30:57 2020 Normal: Finished a list after exitcode: 0 Fri May 1 03:31:20 2020 Normal: --- Startup, daemonizing --- Fri May 1 03:31:20 2020 Normal: recursive startup rsync: /etc/ -> /mnt/ Fri May 1 03:31:20 2020 Normal: Startup of /etc/ -> /mnt/ finished.
You can also check the syncing status with the following command:
tail -f /var/log/lsyncd/lsyncd.status
You should be able to see the changes in the /mnt directory with the following command:
ls /mnt/
You should see that all the files and directories from the /etc directory are added to the /mnt directory:
acpi dconf hosts logrotate.conf newt rc2.d subuid- adduser.conf debconf.conf hosts.allow logrotate.d nginx rc3.d sudoers alternatives debian_version hosts.deny lsb-release nsswitch.conf rc4.d sudoers.d apache2 default init lsyncd ntp.conf rc5.d sysctl.conf apparmor deluser.conf init.d ltrace.conf openal rc6.d sysctl.d apparmor.d depmod.d initramfs-tools lvm opt rcS.d systemd apport dhcp inputrc machine-id os-release resolv.conf terminfo apt dnsmasq.d insserv.conf.d magic overlayroot.conf rmt timezone at.deny docker iproute2 magic.mime PackageKit rpc tmpfiles.d bash.bashrc dpkg iscsi mailcap pam.conf rsyslog.conf ubuntu-advantage bash_completion e2scrub.conf issue mailcap.order pam.d rsyslog.d ucf.conf bash_completion.d environment issue.net manpath.config passwd screenrc udev bindresvport.blacklist ethertypes kernel mdadm passwd- securetty ufw binfmt.d fonts kernel-img.conf mime.types perl security update-manager byobu fstab landscape mke2fs.conf php selinux update-motd.d ca-certificates fuse.conf ldap modprobe.d pki sensors3.conf update-notifier ca-certificates.conf fwupd ld.so.cache modules pm sensors.d vdpau_wrapper.cfg calendar gai.conf ld.so.conf modules-load.d polkit-1 services vim console-setup groff ld.so.conf.d mtab pollinate shadow vmware-tools cron.d group legal multipath popularity-contest.conf shadow- vtrgb cron.daily group- letsencrypt multipath.conf profile shells vulkan cron.hourly grub.d libaudit.conf mysql profile.d skel wgetrc cron.monthly gshadow libnl-3 nanorc protocols sos.conf X11 crontab gshadow- locale.alias netplan pulse ssh xattr.conf cron.weekly gss locale.gen network python3 ssl xdg cryptsetup-initramfs hdparm.conf localtime networkd-dispatcher python3.8 subgid zsh_command_not_found crypttab host.conf logcheck NetworkManager rc0.d subgid- dbus-1 hostname login.defs networks rc1.d subuid
Configure Lsyncd to Synchronize Remote Directories
In this section, we will configure Lsyncd to synchronize /etc/ directory on the local system to the /opt/ directory on the remote system.
Before starting, you will need to setup SSH key-based authentication between the local system and remote server so that the local system can connect to the remote server without password.
On the local system, run the following command to generate a public and private key:
ssh-keygen -t rsa
You should see the following output:
Generating public/private rsa key pair. Enter file in which to save the key (/root/.ssh/id_rsa): Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /root/.ssh/id_rsa Your public key has been saved in /root/.ssh/id_rsa.pub The key fingerprint is: SHA256:c7fhjjhAamFjlk6OkKPhsphMnTZQFutWbr5FnQKSJjE root@ubuntu20 The key's randomart image is: +---[RSA 3072]----+ | E .. | | ooo | | oo= + | |=.+ % o . . | |[email protected] oSo. o | |ooo=B o .o o o | |=o.... o o | |+. o .. o | | . ... . | +----[SHA256]-----+
The above command will generate a private and public key inside ~/.ssh directory.
Next, you will need to copy the public key to the remote server. You can copy it with the following command:
ssh-copy-id root@remote-server-ip
You will be asked to provide the password of the remote root user as shown below:
[email protected]'s password: Number of key(s) added: 1 Now try logging into the machine, with: "ssh '[email protected]'" and check to make sure that only the key(s) you wanted were added.
Once the user is authenticated, the public key will be appended to the remote user authorized_keys file and connection will be closed.
Now, you should be able log in to the remote server without entering password.
To test it just try to login to your remote server via SSH:
ssh root@remote-server-ip
If everything went well, you will be logged in immediately.
Next, you will need to edit the Lsyncd configuration file and define the rsyncssh and target host variables:
nano /etc/lsyncd/lsyncd.conf.lua
Change the file as shown below:
settings {
logfile = "/var/log/lsyncd/lsyncd.log",
statusFile = "/var/log/lsyncd/lsyncd.status",
statusInterval = 20,
nodaemon = false
}
sync {
default.rsyncssh,
source = "/etc/",
host = "remote-server-ip",
targetdir = "/opt"
}
Save and close the file when you are finished. Then, restart the Lsyncd service to start the sync.
systemctl restart lsyncd
You can check the status of synchronization with the following command:
tail -f /var/log/lsyncd/lsyncd.log
You should see the following output:
Fri May 1 04:32:05 2020 Normal: --- Startup, daemonizing --- Fri May 1 04:32:05 2020 Normal: recursive startup rsync: /etc/ -> 45.58.38.21:/opt/ Fri May 1 04:32:06 2020 Normal: Startup of "/etc/" finished: 0
You should be able to see the changes in the /opt directory on the remote server with the following command:
ls /opt
You should see that all the files and directories from the /etc directory are added to the remote server's /opt directory:
acpi dconf hosts logrotate.conf newt rc2.d subuid- adduser.conf debconf.conf hosts.allow logrotate.d nginx rc3.d sudoers alternatives debian_version hosts.deny lsb-release nsswitch.conf rc4.d sudoers.d apache2 default init lsyncd ntp.conf rc5.d sysctl.conf apparmor deluser.conf init.d ltrace.conf openal rc6.d sysctl.d apparmor.d depmod.d initramfs-tools lvm opt rcS.d systemd apport dhcp inputrc machine-id os-release resolv.conf terminfo apt dnsmasq.d insserv.conf.d magic overlayroot.conf rmt timezone at.deny docker iproute2 magic.mime PackageKit rpc tmpfiles.d bash.bashrc dpkg iscsi mailcap pam.conf rsyslog.conf ubuntu-advantage bash_completion e2scrub.conf issue mailcap.order pam.d rsyslog.d ucf.conf bash_completion.d environment issue.net manpath.config passwd screenrc udev bindresvport.blacklist ethertypes kernel mdadm passwd- securetty ufw binfmt.d fonts kernel-img.conf mime.types perl security update-manager byobu fstab landscape mke2fs.conf php selinux update-motd.d ca-certificates fuse.conf ldap modprobe.d pki sensors3.conf update-notifier ca-certificates.conf fwupd ld.so.cache modules pm sensors.d vdpau_wrapper.cfg calendar gai.conf ld.so.conf modules-load.d polkit-1 services vim console-setup groff ld.so.conf.d mtab pollinate shadow vmware-tools cron.d group legal multipath popularity-contest.conf shadow- vtrgb cron.daily group- letsencrypt multipath.conf profile shells vulkan cron.hourly grub.d libaudit.conf mysql profile.d skel wgetrc cron.monthly gshadow libnl-3 nanorc protocols sos.conf X11 crontab gshadow- locale.alias netplan pulse ssh xattr.conf cron.weekly gss locale.gen network python3 ssl xdg cryptsetup-initramfs hdparm.conf localtime networkd-dispatcher python3.8 subgid zsh_command_not_found crypttab host.conf logcheck NetworkManager rc0.d subgid- dbus-1 hostname login.defs networks rc1.d subuid
Conclusion
In the above guide, we learned how to install and configure Lsyncd for local synchronization and remote synchronization. You can now use Lsyncd in the production environment for backup purposes. Feel free to ask me if you have any questions.
