One Good Turn

Backup and Migration

TurnKey Linux has a simple but very practical tool that allows you to back up and migrate application and server configurations: TKLBAM (TurnKey Linux Backup and Migration).

This tool lets you save changes to files, databases, package settings, and more; then, you can restore them on a different system. You only have to set up a TurnKey cloud server to save your backups. The tool is so powerful that you can move or copy fully executable environments within a few minutes. The installation status of the appliances is stored in the backup profiles. TKL takes advantage of the TurnKey Hub, a web service with a front end for backup management. The user links an appliance with a specific Hub account, which in turn is identified by an API key. To avoid fiddling with complicated commands at the console level, the backup mechanism makes use of the Webmin module, so performing backups is possible from any web browser.

The backup mechanism also creates a delta record where changes to files, users, and package management information are stored. The data is calculated for backup time by comparing the current profile status with the backup profile. Whether the backup is stored locally or elsewhere is of secondary importance in terms of processing, but the backup mechanism always uses encryption, and the Hub handles key management. Backups can be saved in the Amazon S3 cloud service and are always available for download via the GeoIP tag to the nearest data center. This ensures optimal performance.

Each TKLBAM-enabled appliance has a corresponding backup profile which comprises the installation status, including an appliance-specific list of files and directories for the backup comparison. However, no files or directories managed by the package management system are included in this list. The delta record data relates to the differences between the installation and the current status. Only the incremental changes are saved and can be restored – with one exception.

Databases are fully backed up unless you configure them differently.

User and group settings are also stored in the Hub services during the backup process. You will find the Backup and Migration module in the Webmin System menu. Before you can use the backup mechanism, you need to create a TurnKey Hub account [4]. Once you have done this, the API key is available via the user profile.

To begin, open the TKLBAM module and enter the user name and key. You can then connect to the TurnKey Hub. You will need a paid account for Amazon S3 to use the cloud-based backup. After registration, the Hub dashboard presents you with the installed TurnKey components (TurnKey Core VM, TurnKey LAMP, TurnKey CouchDB, and so on) that you backed up with the help of the backup function. Use the TKLBAM module functions to execute the backup.

You can set the encryption passphrase by clicking the Passphrase button (Figure 5), which provides additional protection for your backup. If you do not want to bother with encryption, simply leave the fields blank. Clicking the Download Escrow Key icon lets you download a kind of security key that you can use to restore backups again if you have forgotten the encryption passphrase.

Figure 5: The TKLBAM module.

You can determine the size of the backup volume and the frequency of full and incremental backups in the advanced backup settings (Advanced Configuration ), and you can enable daily backups on the TKLBAM overview page by selecting Enable Daily Backups . This page also provides a test function if you select Run a Local Simulation that calculates the required storage space and verifies its availability – in online storage, in particular. The actual backup starts after you click Run Backup .

Conclusions

TurnKey Linux is a must for all administrators who want to evaluate a particular business application with comparatively little effort. The focus is on typical web-based environments such as content management systems and web applications. The amount of infrastructure and the traditional administration tools are unfortunately quite limited. Nevertheless, TurnKey is difficult to beat when it comes to virtual appliances, although it would be useful to be able to post-install other applications.