BackupPC

BackupPC
is a high-performance, enterprise-grade system for backing up Unix, Linux, WinXX, and MacOSX PCs, desktops and laptops to a server's disk. BackupPC is highly configurable and easy to install and maintain.
Given the ever decreasing cost of disks and raid systems, it is now practical and cost effective to backup a large number of machines onto a server's local disk or network storage. For some sites this might be the complete backup solution. For other sites additional permanent archives could be created by periodically backing up the server to tape.
Note that BackupPC only provides file-based backups and restores. In particular, it is not suitable out-of-the-box for "hot" database backups (although pre-backup hooks can be used to dump databases and do "cold" backups); you will need tools like
xtrabackup
for that purpose. Also, BackupPC only offers limited handling of opened files.  Make sure to read about the
limitations of BackupPC
and test a backup-and-restore cycle before you actually need to resort to it for real.
Installation
Install
backuppc
.
Install
rsync
and
perl-file-rsyncp
if you want to use
rsync
as a transport, and
rrdtool
to display usage data in the CGI interface.
Then
start/enable
backuppc.service
.
Placing data directories on a separate partition
The BackupPC pool is stored by default under
/var/lib/backuppc
, which also serves as the home directory for the backuppc user.
This path can be changed via the
$Conf{TopDir}
entry in
/etc/backuppc/config.pl
.
Typical reasons are that you keep your system on a fast, but expensive and small,
SSD
and need to store the backups on a traditional hard disk, or that you want to keep the backup pool on a partition managed by an
LVM
to be able to resize to partition according to changing demands.
The documentation suggests to not change the
$Conf{TopDir}
entry, but instead use symlinks.  However, be careful when doing so because package upgrades for backuppc will replace symlinks for both
/var/lib/backuppc
or any of the default subdirectories
cpool
,
pc
or
pool
by empty directories
without any warning
.
Thus, it is recommended to either use bind mounts in
fstab
instead of symlinks, or to deliberately ignore the recommendation in
/etc/backuppc/config.pl
and change
$Conf{TopDir}
nevertheless. Alternatively, use
pacman
's pre- and post-
transaction hooks
such as the following (remember to make the shell scripts
executable
):
/etc/pacman.d/hooks/backuppc-restore-symlinks-post.hook
[Trigger]
Operation = Upgrade
Type = Package
Target = backuppc

[Action]
Description = Restore symlinks for BackupPC pool directories
When = PostTransaction
Exec = /etc/pacman.d/hooks/backuppc-restore-symlinks-post.sh
/etc/pacman.d/hooks/backuppc-restore-symlinks-post.sh
#!/usr/bin/bash

if [ ! -d /tmp/backuppc-symlinks-cache ]; then
    exit 0
fi

if [ -L /tmp/backuppc-symlinks-cache/backuppc ]; then
    rmdir /var/lib/backuppc/{cpool,pc,pool,}
    mv /tmp/backuppc-symlinks-cache/backuppc /var/lib/
    echo "==> Restored /var/lib/backuppc => $(readlink /var/lib/backuppc)"
fi

for dir in cpool pc pool; do
    if [ -L /tmp/backuppc-symlinks-cache/$dir ]; then
        rmdir /var/lib/backuppc/$dir
        mv /tmp/backuppc-symlinks-cache/$dir /var/lib/backuppc/
        echo "==> Restored /var/lib/backuppc/${dir} => $(readlink /var/lib/backuppc/$dir)"
    fi
done

if [ -f /tmp/backuppc-symlinks-cache/was-running ]; then
    echo '==> BackupPC service was stopped for upgrade.'
    echo '==> Check the configuration and run `systemctl start backuppc.service` to restart the service.'
    rm -f /tmp/backuppc-symlinks-cache/was-running
fi

rmdir --ignore-fail-on-non-empty /tmp/backuppc-symlinks-cache &>/dev/null
/etc/pacman.d/hooks/backuppc-restore-symlinks-pre.hook
[Trigger]
Operation = Upgrade
Type = Package
Target = backuppc

[Action]
Description = Stash symlinks for BackupPC pool directories
When = PreTransaction
Exec = /etc/pacman.d/hooks/backuppc-restore-symlinks-pre.sh
/etc/pacman.d/hooks/backuppc-restore-symlinks-pre.sh
#!/usr/bin/bash

if systemctl is-active backuppc.service &>/dev/null; then
    systemctl stop backuppc.service
    mkdir -p /tmp/backuppc-symlinks-cache
    touch /tmp/backuppc-symlinks-cache/was-running
fi

for dir in /var/lib/backuppc/{cpool,pc,pool,}; do
    if [ -L $dir ]; then
        mkdir -p /tmp/backuppc-symlinks-cache
        mv $dir /tmp/backuppc-symlinks-cache
    fi
done
Apache configuration
BackupPC has a web interface that allows you to easily control it. You can access it using Apache and mod_perl or a C wrapper but other webservers like
lighttpd
works too.
Install
apache
.
Edit Apache configuration
BackupPC's web UI needs to run as the user backuppc, but Apache normally runs under the user http. There are several ways to fix this. The two demonstrated here are common for single-purpose servers (Apache is only used to serve the BackupPC UI) or for multi-purpose servers (Apache may also server other websites under the regular http user).
Setting up Apache for single-purpose use is a bit easier but not as flexible.
General settings
Edit
/etc/backuppc/config.pl
. Set administrator name:
$Conf{CgiAdminUsers} = 'admin';
Next, we need to add a users file and set the admin password:
# htpasswd -c /etc/backuppc/backuppc.users admin
The BackupPC-Webfrontend is initially configured so that you can only access it from the localhost. If you want to access it from all machines in your network, you have to edit
/etc/httpd/conf/extra/backuppc.conf
. Edit the line:
Require ip 127.0.0.1
to:
Require ip 127.0.0.1 192.168.0
where you have to replace 192.168.0 to your corresponding IP-Adresses you want to gain access from.
After one of the configuration steps below has also been performed, [re]start the Apache service.
Single-purpose Apache settings
Install
mod_perl
AUR
.
Edit the Apache configuration file to load mod_perl, tell Apache to run as user backuppc and to include
/etc/httpd/conf/extra/backuppc.conf
:
/etc/httpd/conf/httpd.conf
LoadModule perl_module modules/mod_perl.so
User backuppc
Group backuppc
Include conf/extra/backuppc.conf
Multi-purpose Apache settings
Instead of globally changing the Apache user and group like in the example above, we will instead make Apache run just the BackupPC CGI script as the backuppc user and leave the default user alone. This method uses mod_cgi to call a wrapper written in C instead of using the extra mod_perl dependency. You still need to have
perl
itself installed so the wrapper can run the BackupPC scripts.
Make sure Apache can run CGI programs (the line loading mod_cgi is not commented) and that it reads the BackupPC configuration by including it in
/etc/httpd/conf/extra/backuppc.conf
:
/etc/httpd/conf/httpd.conf
LoadModule cgi_module modules/mod_cgi.so
Include conf/extra/backuppc.conf
The webserver user and the suid problem
The current setup of BackupPC, the webserver needs to run as backuppc user and this can be a problem on many setups where the webserver is used for other sites. In the past one could suid a Perl script, but it was blocked globally due security problems several years ago. To workaround that, perl-suid was used, but again blocked due the same problem  more recently, scripts cannot be run securely with suid bit. Still there is another way, this time using a simple binary program that is suid as a launcher, that will run the backuppc Perl scripts already with the correct user. This isolates the Perl script from the environment and it is considered safe.
You need to replace the original backuppc CGI  with the below C code compiled program and move the backuppc CGI to another place.
Move the real CGI
/usr/share/backuppc/cgi-bin/BackupPC_Admin
to the lib directory
/usr/share/backuppc/lib/real-BackupPC_Admin.cgi
.
Save the C code below to a file named
wrapper.c
(please update the CGI path if needed) and compile it with:
$ gcc -o BackupPC_Admin wrapper.c
Note
If the compile fails with the error
type of ‘ac’ defaults to ‘int’
, you can force gcc to use C89 standard with
$ gcc -std=c89 -o BackupPC_Admin wrapper.c
The wrapper C code:
#include <unistd.h>
#define REAL_PATH "/usr/share/backuppc/lib/real-BackupPC_Admin.cgi"
int main(ac, av)
char **av;
{
   execv(REAL_PATH, av);
   return 0;
}
Place the new binary
BackupPC_Admin
in the cgi-bin directory and chown the binary CGI to
backuppc:http
and set the suid bit:
# chown backuppc:http /usr/share/backuppc/cgi-bin/BackupPC_Admin
# chmod 4750 /usr/share/backuppc/cgi-bin/BackupPC_Admin
Do not forget to clear the suid bit on the original Perl script if it was set (or the CGI page will not load):
# chmod 0755 /usr/share/backuppc/lib/real-BackupPC_Admin.cgi
Keep your web server with its usual user and backup should now be able to run correctly.
Note
Keep in mind that the fix described in this section will be overwritten at every package upgrade, resulting in the BackupPC_Admin page displaying a message similar to
Error: Wrong user: my userid is 33, instead of 126(backuppc)
. You will have to reapply the whole modification  manually again to fix it.
Alternative nginx configuration
Install
nginx-mainline
and
fcgiwrap
.
Create those two directories :
# mkdir /etc/nginx/sites-available
# mkdir /etc/nginx/sites-enabled
Edit nginx configuration file to include the configuration files from
sites-enabled
, by adding this at the end of the http block :
/etc/nginx/nginx.conf
http {
    ...
    include sites-enabled/*;
}
/etc/nginx/sites-available/backuppc
server {
    listen <your_server_port>;
    server_name <your_server_name>;

    root  /usr/share/backuppc/html;
    index /index.cgi;

    access_log  /var/log/nginx/backuppc.access.log;
    error_log   /var/log/nginx/backuppc.error.log;

    location / {
        allow 127.0.0.1/32;
        # allow 192.168.0.0/24;
        deny all;

        # auth_basic "Backup";
        # auth_basic_user_file conf/backuppc.users;

        location /backuppc {
            alias /usr/share/backuppc/html;
        }

        location ~ \.cgi$ {
            include fastcgi_params;
            fastcgi_pass unix:/run/fcgiwrap.sock;

            fastcgi_param REMOTE_ADDR     $remote_addr;
            fastcgi_param REMOTE_USER     $remote_user;
            fastcgi_param SCRIPT_FILENAME /usr/share/backuppc/cgi-bin/BackupPC_Admin;
        }
    }
}
And symlink to sites-enabled:
# ln -s /etc/nginx/sites-available/backuppc /etc/nginx/sites-enabled
Edit
the executing user in
fcgiwrap.service
file to
backuppc
.
Enable/start
nginx.service
and
fcgiwrap.socket
.
If you want to use basic authentication, uncomment the corresponding lines above and create the file
/etc/nginx/conf/backuppc.users
containing all allowed users :
# echo -n 'myuser:' >> /etc/nginx/conf/backuppc.users
# openssl passwd -apr1 >> /etc/nginx/conf/backuppc.users
Follow
Certbot#Nginx
to create a Let's Encrypt certificate and configure a TLS certificate.
Alternative lighttpd configuration
Install
the
lighttpd
package.
/etc/lighttpd/lighttpd.conf
server.port             = 81
 server.username         = "backuppc"
 server.groupname        = "backuppc"
 server.document-root    = "/srv/http"
 server.errorlog         = "/var/log/lighttpd/error.log"
 dir-listing.activate    = "enable"
 index-file.names        = ( "index.html", "index.php", "index.cgi" )
 mimetype.assign         = ( ".html" => "text/html", ".txt" => "text/plain", ".jpg" => "image/jpeg", ".png" => "image/png", "" => "application/octet-stream" )

 server.modules = ("mod_alias", "mod_cgi", "mod_auth", "mod_access" )

 alias.url               = ( "/BackupPC_Admin" => "/usr/share/backuppc/cgi-bin/BackupPC_Admin" )
 alias.url               += ( "/backuppc" => "/usr/share/backuppc/html" )

 cgi.assign              += ( ".cgi" => "/usr/bin/perl" )
 cgi.assign              += ( "BackupPC_Admin" => "/usr/bin/perl" )

 auth.backend = "plain"
 auth.backend.plain.userfile = "/etc/lighttpd/passwd"
 auth.require = ( "/BackupPC_Admin" => ( "method" => "basic", "realm" => "BackupPC", "require" => "user=admin" ) )
/etc/lighttpd/passwd
admin:
yourpassword
And create log file:
# touch /var/log/lighttpd/error.log
# chown backuppc:backuppc /var/log/lighttpd/error.log
For HTTPS support and configuration please check the
lighttpd article
.
Start
start/enable
the
lighttpd.service
and point your browser to
https://localhost:81/BackupPC_Admin
.
lighttpd systemd hardening note (Arch Linux)
On Arch Linux, the packaged
lighttpd.service
uses systemd hardening (
ProtectSystem=full
), which mounts
/etc
read-only inside the lighttpd service namespace.  
Since BackupPC’s web interface writes configuration files under
/etc/backuppc
, configuration updates via the web UI will fail unless write access is explicitly allowed.
To permit this while keeping systemd hardening enabled, create a systemd override for lighttpd:
/etc/systemd/system/lighttpd.service.d/override.conf
[Unit]
After=backuppc.service
Requires=backuppc.service

[Service]
ReadWritePaths=/etc/backuppc
Then reload and restart the service:
# systemctl daemon-reload
# systemctl restart lighttpd.service
This ensures the BackupPC service is available before lighttpd starts and allows the web interface to save configuration changes.
Accessing the admin page
Before accessing the admin page you have to specify which users/groups will be able to edit BackupPC's configuration.
/etc/backuppc/config.pl
$Conf{CgiAdminUserGroup} = '<authorized groups>';
$Conf{CgiAdminUsers}     = '<authorized users>';  # <-- set to '*' if the webserver is not autenticating users
Browse to
http://localhost/BackupPC_Admin
respectively http://
your_backuppc_server_ip
/BackupPC_Admin.
Website view problem
Due an Apache directive, the web interface may not shown properly. If that is your case, just modify the line in your
/etc/httpd/conf/httpd.conf
that avoids .htaccess and .htpasswd from viewed for clients or change directory name /usr/share/backuppc/html for /usr/share/backuppc/files and update
/etc/httpd/conf/extra/backuppc.conf
with the new path, as it follows:
/etc/httpd/conf/extra/backuppc.conf
Alias           /BackupPC/images        /usr/share/BackupPC/files/
See also
BackupPC Home page
BackupPC documentation