Encrypted InnoDB tablespace backups

InnoDB supports data encryption for InnoDB tables stored in file-per-table tablespaces. This feature provides an at-rest encryption for physical tablespace data files.

For an authenticated user or application to access an encrypted tablespace, InnoDB uses the master encryption key to decrypt the tablespace key. The master encryption key is stored in a keyring. xtrabackup supports two keyring plugins: keyring_file, and keyring_vault. These plugins are installed into the plugin directory.

Version updates

Percona XtraBackup 8.0.25-17 adds support for the keyring_file component, which is part of the component-based infrastructure MySQL which extends the server capabilities. The component is stored in the plugin directory.

See a comparison of keyring components and keyring plugins for more information.

Percona XtraBackup 8.0.27-19 adds support for the Key Management Interoperability Protocol (KMIP) which enables the communication between the key management system and encrypted database server. This feature is tech preview quality.

Percona XtraBackup 8.0.28-21 adds support for the Amazon Key Management Service (AWS KMS). AWS KMS is cloud-based encryption and key management service. The keys and functionality can be used for other AWS services or your applications that use AWS. No configuration is required to back up a server with AWS KMS-enabled encryption. This feature is tech preview quality.

Use keyring_file plugin

In order to back up and prepare a database containing encrypted InnoDB
tablespaces, specify the path to a keyring file as the value of the --keyring-file-data option.

$ xtrabackup --backup --target-dir=/data/backup/ --user=root \
--keyring-file-data=/var/lib/mysql-keyring/keyring

After xtrabackup takes the backup, the following message confirms the action:

Confirmation message

xtrabackup: Transaction log of lsn (5696709) to (5696718) was copied.
160401 10:25:51 completed OK!

Warning

xtrabackup does not copy the keyring file into the backup directory. To prepare the backup, you must copy the keyring file manually.

Prepare the backup with the keyring_file plugin

To prepare the backup specify the keyring-file-data.

$ xtrabackup --prepare --target-dir=/data/backup \
--keyring-file-data=/var/lib/mysql-keyring/keyring

After xtrabackup takes the backup, the following message confirms the action:

Confirmation message

InnoDB: Shutdown completed; log sequence number 5697064
160401 10:34:28 completed OK!

The backup is now prepared and can be restored with the --copy-back option. In case the keyring has been rotated, you must restore the keyring used when the backup was taken and prepared.

Use keyring_vault plugin

Keyring vault plugin settings are described here.

Create a backup with the keyring_vault plugin

The following command creates a backup in the /data/backup directory:

$ xtrabackup --backup --target-dir=/data/backup --user=root

After xtrabackup completes the action, the following message confirms the action:

Confirmation message

xtrabackup: Transaction log of lsn (5696709) to (5696718) was copied.
160401 10:25:51 completed OK!

Prepare the backup with the keyring_vault plugin

To prepare the backup, xtrabackup must access the keyring. xtrabackup does not communicate with the MySQL server or read the default my.cnf configuration file. Specify the keyring settings in the command line:

$ xtrabackup --prepare --target-dir=/data/backup \
--keyring-vault-config=/etc/vault.cnf

Note

Please look using the keyring vault plugin for a description of keyring vault plugin settings.

After xtrabackup completes the action, the following message confirms the action:

Confirmation message

InnoDB: Shutdown completed; log sequence number 5697064
160401 10:34:28 completed OK!

The backup is now prepared and can be restored with the --copy-back option:

$ xtrabackup --copy-back --target-dir=/data/backup --datadir=/data/mysql

Use the keyring_file component

A component is not loaded with the --early_plugin_load option. The server uses a manifest to load the component and the component has its own configuration file. See the MySQL documentation on the component installation for more information.

An example of a manifest and a configuration file follows:

An example of ./bin/mysqld.my:

{
   "components": "file://component_keyring_file"
}

An example of /lib/plugin/component_keyring_file.cnf:

{
   "path": "/var/lib/mysql-keyring/keyring_file", "read_only": false
}

For more information, see Keyring Component Installation and Using the keyring_file File-Based Keyring Plugin.

With the appropriate privilege, you can SELECT on the performance_schema.keyring_component_status table to view the attributes and status of the installed keyring component when in use.

The component has no special requirements for backing up a database that contains encrypted InnoDB tablespaces.

$ xtrabackup --backup --target-dir=/data/backup --user=root

After xtrabackup completes the action, the following message confirms the action:

Confirmation message

xtrabackup: Transaction log of lsn (5696709) to (5696718) was copied.
160401 10:25:51 completed OK!

Warning

xtrabackup does not copy the keyring file into the backup directory. To prepare the backup, you must copy the keyring file manually.

Prepare the backup with the keyring_file component

xtrabackup reads the keyring_file component configuration from xtrabackup_component_keyring_file.cnf. You must specify the keyring_file data path if the keyring-file-data is not located in the attribute PATH from the xtrabackup_component_keyring_file.cnf.

The following is an example of adding the location for the keyring-file-data:

$ xtrabackup --prepare --target-dir=/data/backup \
--keyring-file-data=/var/lib/mysql-keyring/keyring

Note

xtrabackup attempts to read xtrabackup_component_keyring_file.cnf. You can assign another keyring file component configuration by passing the --component-keyring-file-config option.

After xtrabackup completes preparing the backup, the following message confirms the action:

Confirmation message

InnoDB: Shutdown completed; log sequence number 5697064
160401 10:34:28 completed OK!

The backup is prepared. To restore the backup use the --copy-back option. If the keyring has been rotated, you must restore the specific keyring used to take and prepare the backup.

Incremental encrypted InnoDB tablespace backups with keyring_file

The process of taking incremental backups with InnoDB tablespace encryption is similar to taking the Incremental Backups with unencrypted tablespace.

Note

The keyring-file component should not used in production or for regulatory compliance.

Create an incremental backup

To make an incremental backup, begin with a full backup. The xtrabackup binary writes a file called xtrabackup_checkpoints into the backup’s target directory. This file contains a line showing the to_lsn, which is the database’s LSN at the end of the backup. First you need to create a full backup with the following command:

$ xtrabackup --backup --target-dir=/data/backups/base \
--keyring-file-data=/var/lib/mysql-keyring/keyring

Warning

xtrabackup will not copy the keyring file into the backup directory. In order to prepare the backup, you must make a copy of the keyring file yourself. If you try to restore the backup after the keyring has been changed you’ll see errors like ERROR 3185 (HY000): Can't find master key from keyring, please check keyring plugin is loaded. when trying to access an encrypted table.

If you look at the xtrabackup_checkpoints file, you should see the output similar to the following:

Expected output

backup_type = full-backuped
from_lsn = 0
to_lsn = 7666625
last_lsn = 7666634
compact = 0
recover_binlog_info = 1

Now that you have a full backup, you can make an incremental backup based on it. Use a command such as the following:

$ xtrabackup --backup --target-dir=/data/backups/inc1 \
--incremental-basedir=/data/backups/base \
--keyring-file-data=/var/lib/mysql-keyring/keyring

Warning

xtrabackup does not copy the keyring file into the backup directory. To prepare the backup, you must copy the keyring file manually.

If the keyring has not been rotated you can use the same as the one you’ve backed-up with the base backup. If the keyring has been rotated, or you have upgraded the plugin to a component, you must back up the keyring file. Otherwise, you cannot prepare the backup.

The /data/backups/inc1/ directory should now contain delta files, such as ibdata1.delta and test/table1.ibd.delta. These represent the changes since the LSN 7666625. If you examine the xtrabackup_checkpoints file in this directory, you should see the output similar to the following:

Expected output

backup_type = incremental
from_lsn = 7666625
to_lsn = 8873920
last_lsn = 8873929
compact = 0
recover_binlog_info = 1

Use this directory as the base for yet another incremental backup:

$ xtrabackup --backup --target-dir=/data/backups/inc2 \
--incremental-basedir=/data/backups/inc1 \
--keyring-file-data=/var/lib/mysql-keyring/keyring

Prepare incremental backups

The --prepare step for incremental backups is not the same as for normal backups. In normal backups, two types of operations are performed to make the database consistent: committed transactions are replayed from the log file against the data files, and uncommitted transactions are rolled back. You must skip the rollback of uncommitted transactions when preparing a backup, because transactions that were uncommitted at the time of your backup may be in progress, and it’s likely that they will be committed in the next incremental backup. You should use the --apply-log-only option to prevent the rollback phase.

Warning

If you do not use the --apply-log-only option to prevent the rollback phase, then your incremental backups are useless. After transactions have been rolled back, further incremental backups cannot be applied.

Beginning with the full backup you created, you can prepare it and then apply the incremental differences to it. Recall that you have the following backups:

/data/backups/base
/data/backups/inc1
/data/backups/inc2

To prepare the base backup, you need to run --prepare as usual, but prevent the rollback phase:

$ xtrabackup --prepare --apply-log-only --target-dir=/data/backups/base \
--keyring-file-data=/var/lib/mysql-keyring/keyring

Expected output

InnoDB: Shutdown completed; log sequence number 7666643
InnoDB: Number of pools: 1
160401 12:31:11 completed OK!

To apply the first incremental backup to the full backup, you should use the following command:

$ xtrabackup --prepare --apply-log-only --target-dir=/data/backups/base \
--incremental-dir=/data/backups/inc1 \
--keyring-file-data=/var/lib/mysql-keyring/keyring

Warning

The backup should be prepared with the keyring file and type that was used when backup was being taken. This means that if the keyring has been rotated, or you have upgraded from a plugin to a component between the base and incremental backup that you must use the keyring that was in use when the first incremental backup has been taken.

Preparing the second incremental backup is a similar process: apply the deltas to the (modified) base backup, and you will roll its data forward in time to the point of the second incremental backup:

$ xtrabackup --prepare --target-dir=/data/backups/base \
--incremental-dir=/data/backups/inc2 \
--keyring-file-data=/var/lib/mysql-keyring/keyring

Note

--apply-log-only should be used when merging all incremental backups except the last one. That’s why the previous line does not contain the --apply-log-only option. Even if the --apply-log-only was used on the last step, backup would still be consistent but in that case server would perform the rollback phase.

The backup is now prepared and can be restored with --copy-back option. In case the keyring has been rotated you’ll need to restore the keyring which was used to take and prepare the backup.

Use the Key Management Interoperability Protocol (KMIP)

This feature is tech preview quality.

Percona XtraBackup 8.0.27-19 adds support for the Key Management Interoperability Protocol (KMIP) which enables the communication between the key management system and encrypted database server.

Percona XtraBackup has no special requirements for backing up a database that contains encrypted InnoDB tablespaces.

Percona XtraBackup performs the following actions:

1. Connects to the MySQL server

2. Pulls the configuration

3. Connects to the KMIP server

4. Fetches the necessary keys from the KMIP server

5. Stores the KMIP server configuration settings in the xtrabackup_component_keyring_kmip.cnf file in the backup directory

When preparing the backup, Percona XtraBackup connects to the KMIP server with the settings from the xtrabackup_component_keyring_kmip.cnf file.

Restore a backup when the keyring is not available

While the described restore method works, this method requires access to the same keyring that the server is using. It may not be possible if the backup is prepared on a different server or at a much later time, when keys in the keyring are purged, or, in the case of a malfunction, when the keyring vault server is not available at all.

The --transition-key=<passphrase> option should be used to make it possible for xtrabackup to process the backup without access to the keyring vault server. In this case, xtrabackup derives the AES encryption key from the specified passphrase and will use it to encrypt tablespace keys of tablespaces that are being backed up.

Create a backup with a passphrase

The following example illustrates how the backup can be created in this case:

$ xtrabackup --backup --user=root -p --target-dir=/data/backup \
--transition-key=MySecretKey

If --transition-key is specified without a value, xtrabackup will ask for it.

Note

xtrabackup scrapes --transition-key so that its value is not visible in the ps command output.

Prepare a backup with a passphrase

The same passphrase should be specified for the prepare command:

$ xtrabackup --prepare --target-dir=/data/backup \
--transition-key=MySecretKey

There are no --keyring-vault...,``–keyring-file…``, or --component-keyring-file-config options here, because xtrabackup does not talk to the keyring in this case.

Restore a backup with a generated key

When restoring a backup you will need to generate a new master key. Here is the example for keyring_file plugin or component:

$ xtrabackup --copy-back --target-dir=/data/backup --datadir=/data/mysql \
--transition-key=MySecretKey --generate-new-master-key \
--keyring-file-data=/var/lib/mysql-keyring/keyring

In case of keyring_vault, it will look like this:

$ xtrabackup --copy-back --target-dir=/data/backup --datadir=/data/mysql \
--transition-key=MySecretKey --generate-new-master-key \
--keyring-vault-config=/etc/vault.cnf

xtrabackup will generate a new master key, store it in the target keyring vault server and re-encrypt the tablespace keys using this key.

Make a backup with a stored transition key

Finally, there is an option to store a transition key in the keyring. In this case, xtrabackup will need to access the same keyring file or vault server during prepare and copy-back but does not depend on whether the server keys have been purged.

In this scenario, the three stages of the backup process look as follows.

• Backup

$ xtrabackup --backup --user=root -p --target-dir=/data/backup \
--generate-transition-key

• Prepare

  • keyring_file variant:

  $ xtrabackup --prepare --target-dir=/data/backup \
  --keyring-file-data=/var/lib/mysql-keyring/keyring
  

  • keyring_vault variant:

  $ xtrabackup --prepare --target-dir=/data/backup \
  --keyring-vault-config=/etc/vault.cnf
  

• Copy-back

• keyring_file variant:

  $ xtrabackup --copy-back --target-dir=/data/backup --datadir=/data/mysql \
  --generate-new-master-key --keyring-file-data=/var/lib/mysql-keyring/keyring
  

• keyring_vault variant:

  $ xtrabackup --copy-back --target-dir=/data/backup --datadir=/data/mysql \
  --generate-new-master-key --keyring-vault-config=/etc/vault.cnf
  

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Last update: 2023-01-09