The synopsis of the custom script is as follows:
SCRIPT {-backup-restore} -properties FILE -options OPTIONS
Where:
-backup — indicates
that the script should work in the backup mode and create a backup.
-restore — indicates
that the scrip should work in the restore mode and restore a previous
backup.
-properties — defines
the name of the properties file. When called in
backup mode, the properties file should be
updated by the script with the location of the generated backup file.
When called in restore mode, the file should be
examined by the script to determine the backup file that will be used
to perform the restore operation.
-options — specifies
any unique options to the script.
The custom script must support the following:
The script must be capable of performing both the backup and the
restore operation. Tungsten Replicator selects the operation by
providing the -backup or
-restore option to the
script on the command-line.
The script must parse command-line arguments to extract the operation type, properties file and other settings.
Accept the name of the properties file to be used during the backup process. This is supplied on the command-line using the format:
-properties FILENAME
The properties file is used by Tungsten Replicator to exchange information about the backup or restore.
Must parse any additional options supplied on the command-line using the format:
-options ARG1=VAL1&ARG2=VAL2
Must be responsible for executing whatever steps are required to create a consistent snapshot of the dataserver
Must place the contents of the database backup into a single file. If the backup process generates multiple files, then the contents should be packaged using tar or zip.
The script has to determine the files that were generated during the backup process and collect them into a single file as appropriate.
Must update the supplied properties with the name of the backup file generated, as follows:
file=BACKUPFILE
If the file has not been updated with the information, or the file cannot be found, then the backup is considered to have failed.
Once the backup process has completed, the backup file specified in
the properties file will be moved to the configured backup location
(for example /opt/continuent/backups).
Tungsten Replicator will forward all
STDOUT and
STDERR from the script to the
log file script.log within the
log directory. This file is recreated each time a backup is executed.
Script should have an exit (return) value of 0 for success, and 1 for failure. The script is responsible for handling any errors in the underlying backup tool or script used to perform the backup, but it must then pass the corresponding success or failure condition using the exit code.
A sample Ruby script that creates a simple text file as the backup content, but demonstrates the core operations for the script is shown below:
#!/usr/bin/env ruby
require "/opt/continuent/tungsten/cluster-home/lib/ruby/tungsten"
require "/opt/continuent/tungsten/tungsten-replicator/lib/ruby/backup"
class MyCustomBackupScript < TungstenBackupScript
def backup
TU.info("Take a backup with arg1 = #{@options[:arg1]} and myarg = #
{@options[:myarg]}")
storage_file = "/opt/continuent/backups/backup_" +
Time.now.strftime("%Y-%m-%d_%H-%M") + "_" + rand(100).to_s()
# Take a backup of the server and store the information to
storage_file
TU.cmd_result("echo 'my backup' > #{storage_file}")
# Write the filename to the final storage file
TU.cmd_result("echo \"file=#{storage_file}\" > #
{@options[:properties]}")
end
def restore
storage_file = TU.cmd_result(". #{@options[:properties]}; echo
$file")
TU.info("Restore a backup from #{storage_file} with arg1 = #
{@options[:arg1]} and myarg = #{@options[:myarg]}")
# Process the contents of storage_file to restore into the database
server
endAn alternative script using Perl is provided below:
#!/usr/bin/perl
use strict;
use warnings;
use Getopt::Long;
use IO::File;
my $argstring = join(' ',@ARGV);
my ($backup,$restore,$properties,$options) = (0,0,'','');
my $result = GetOptions("backup" => \$backup,
"restore" => \$restore,
"properties=s" => \$properties,
"options=s" => \$options,
);
if ($backup)
{
my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time);
my $backupfile = sprintf('mcbackup.%04d%02d%02d-%02d%02d%02d-%02d.dump',
($year+1900),$mon,$mday,$hour,$min,$sec,$$);
my $out = IO::File->new($backupfile,'w') or die "Couldn't open the backup file: $backupfile";
# Fake backup data
print $out "Backup data!\n";
$out->close();
# Update the properties file
my $propfile = IO::File->new($properties,'w') or die "Couldn't write to the properties file";
print $propfile "file=$backupfile\n";
$propfile->close();
}
if ($restore)
{
warn "Would be restoring information using $argstring\n";
}
exit 0;