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WAL-G

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This documentation is also available at wal-g.readthedocs.io

WAL-G is an archival restoration tool for PostgreSQL, MySQL/MariaDB, and MS SQL Server (beta for MongoDB and Redis).

WAL-G is the successor of WAL-E with a number of key differences. WAL-G uses LZ4, LZMA, or Brotli compression, multiple processors, and non-exclusive base backups for Postgres. More information on the original design and implementation of WAL-G can be found on the Citus Data blog post "Introducing WAL-G by Citus: Faster Disaster Recovery for Postgres".

Table of Contents

Installation

A precompiled binary for Linux AMD 64 of the latest version of WAL-G can be obtained under the Releases tab.

Binary name has the following format: wal-g-DBNAME-OSNAME, where DBNAME stands for the name of the database (for example pg, mysql), OSNAME stands for the name of the operating system used for building the binary.

To decompress the binary, use:

tar -zxvf wal-g-DBNAME-OSNAME-amd64.tar.gz
mv wal-g-DBNAME-OSNAME-amd64 /usr/local/bin/wal-g

For example, for Postgres and Ubuntu 18.04:

tar -zxvf wal-g-pg-ubuntu-18.04-amd64.tar.gz
mv wal-g-pg-ubuntu-18.04-amd64 /usr/local/bin/wal-g

For other systems, please consult the Development section for more information.

Configuration

Storage

To configure where WAL-G stores backups, please consult the Storages section.

Compression

  • WALG_COMPRESSION_METHOD

To configure the compression method used for backups. Possible options are: lz4, lzma, brotli. The default method is lz4. LZ4 is the fastest method, but the compression ratio is bad. LZMA is way much slower. However, it compresses backups about 6 times better than LZ4. Brotli is a good trade-off between speed and compression ratio, which is about 3 times better than LZ4.

Encryption

  • YC_CSE_KMS_KEY_ID

To configure Yandex Cloud KMS key for client-side encryption and decryption. By default, no encryption is used.

  • YC_SERVICE_ACCOUNT_KEY_FILE

To configure the name of a file containing private key of Yandex Cloud Service Account. If not set a token from the metadata service (http://169.254.169.254) will be used to make API calls to Yandex Cloud KMS.

  • WALG_LIBSODIUM_KEY

To configure encryption and decryption with libsodium. WAL-G uses an algorithm that only requires a secret key.

  • WALG_LIBSODIUM_KEY_PATH

Similar to WALG_LIBSODIUM_KEY, but value is the path to the key on file system. The file content will be trimmed from whitespace characters.

  • WALG_GPG_KEY_ID (alternative form WALE_GPG_KEY_ID) ⚠️ DEPRECATED

To configure GPG key for encryption and decryption. By default, no encryption is used. Public keyring is cached in the file "/.walg_key_cache".

  • WALG_PGP_KEY

To configure encryption and decryption with OpenPGP standard. You can join multiline key using \n symbols into one line (mostly used in case of daemontools and envdir). Set private key value when you need to execute wal-fetch or backup-fetch command. Set public key value when you need to execute wal-push or backup-push command. Keep in mind that the private key also contains the public key.

  • WALG_PGP_KEY_PATH

Similar to WALG_PGP_KEY, but value is the path to the key on file system.

  • WALG_PGP_KEY_PASSPHRASE

If your private key is encrypted with a passphrase, you should set passphrase for decrypt.

Database-specific options

More options are available for the chosen database. See it in Databases

Usage

WAL-G currently supports these commands for all type of databases:

backup-list

Lists names and creation time of available backups.

--pretty flag prints list in a table

--json flag prints list in JSON format, pretty-printed if combined with --pretty

--detail flag prints extra backup details, pretty-printed if combined with --pretty, json-encoded if combined with --json

delete

Is used to delete backups and WALs before them. By default, delete will perform a dry run. If you want to execute deletion, you have to add --confirm flag at the end of the command. Backups marked as permanent will not be deleted.

delete can operate in four modes: retain, before, everything and target.

retain [FULL|FIND_FULL] %number% [--after %name|time%]

if FULL is specified, keep %number% full backups and everything in the middle. If with --after flag is used keep $number$ the most recent backups and backups made after %name|time% (including).

before [FIND_FULL] %name%

If FIND_FULL is specified, WAL-G will calculate minimum backup needed to keep all deltas alive. If FIND_FULL is not specified, and call can produce orphaned deltas, the call will fail with the list.

everything [FORCE]

target [FIND_FULL] %name% | --target-user-data %data% will delete the backup specified by name or user data. Unlike other delete commands, this command does not delete any archived WALs.

(Only in Postgres) By default, if delta backup is provided as the target, WAL-G will also delete all the dependant delta backups. If FIND_FULL is specified, WAL-G will delete all backups with the same base backup as the target.

Examples

everything all backups will be deleted (if there are no permanent backups)

everything FORCE all backups, include permanent, will be deleted

retain 5 will fail if 5th is delta

retain FULL 5 will keep 5 full backups and all deltas of them

retain FIND_FULL 5 will find necessary full for 5th and keep everything after it

retain 5 --after 2019-12-12T12:12:12 keep 5 most recent backups and backups made after 2019-12-12 12:12:12

before base_000010000123123123 will fail if base_000010000123123123 is delta

before FIND_FULL base_000010000123123123 will keep everything after base of base_000010000123123123

target base_0000000100000000000000C9 delete the base backup and all dependant delta backups

target --target-user-data "{ \"x\": [3], \"y\": 4 }" delete backup specified by user data

target base_0000000100000000000000C9_D_0000000100000000000000C4 delete delta backup and all dependant delta backups

target FIND_FULL base_0000000100000000000000C9_D_0000000100000000000000C4 delete delta backup and all delta backups with the same base backup

More commands are available for the chosen database engine. See it in Databases

Storage tools (danger zone)

wal-g st command series allows interacting with the configured storage. Be aware that these commands can do potentially harmful operations and make sure that you know what you're doing.

ls

Prints listing of the objects in the provided storage folder.

wal-g st ls get listing with all objects and folders in the configured storage.

wal-g st ls -r get recursive listing with all objects in the configured storage.

wal-g st ls some_folder/some_subfolder get listing with all objects in the provided storage path.

get

Download the specified storage object. By default, the command will try to apply the decompression and decryption (if configured).

Flags:

  1. Add --no-decompress to download the remote object without decompression
  2. Add --no-decrypt to download the remote object without decryption

Examples:

wal-g st get path/to/remote_file path/to/local_file download the file from storage.

wal-g st get path/to/remote_file path/to/local_file --no-decrypt download the file from storage without decryption.

cat

Show the specified storage object to STDOUT. By default, the command will NOT try to decompress and decrypt it. Useful for getting sentinels and other meta-information files.

Flags:

  1. Add --decompress to decompress source file
  2. Add --decrypt to decrypt source file

Examples:

wal-g st cat path/to/remote_file.json show remote_file.json

rm

Remove the specified storage object.

Example:

wal-g st rm path/to/remote_file remove the file from storage.

put

Upload the specified file to the storage. By default, the command will try to apply the compression and encryption (if configured).

Flags:

  1. Add --no-compress to upload the object without compression
  2. Add --no-encrypt to upload the object without encryption

Example:

wal-g st put path/to/local_file path/to/remote_file upload the local file to storage.

Databases

PostgreSQL

Information about installing, configuration and usage

MySQL/MariaDB

Information about installing, configuration and usage

SQLServer

Information about installing, configuration and usage

Mongo [Beta]

Information about installing, configuration and usage

FoundationDB [Work in progress]

Information about installing, configuration and usage

Redis [Beta]

Information about installing, configuration and usage

Development

Installing

It is specified for your type of database.

Testing

WAL-G relies heavily on unit tests. These tests do not require S3 configuration as the upload/download parts are tested using mocked objects. Unit tests can be run using

make unittest

For more information on testing, please consult test, testtools and unittest section in Makefile.

WAL-G will perform a round-trip compression/decompression test that generates a directory for data (e.g., data...), compressed files (e.g., compressed), and extracted files (e.g., extracted). These directories will only get cleaned up if the files in the original data directory match the files in the extracted one.

Test coverage can be obtained using:

make coverage

This command generates coverage.out file and opens HTML representation of the coverage.

Development on Windows

Information about installing and usage

Authors

See also the list of contributors who participated in this project.

License

This project is licensed under the Apache License, Version 2.0, but the lzo support is licensed under GPL 3.0+. Please refer to the LICENSE.md file for more details.

Acknowledgments

WAL-G would not have happened without the support of Citus Data

WAL-G came into existence as a result of the collaboration between a summer engineering intern at Citus, Katie Li, and Daniel Farina, the original author of WAL-E, who currently serves as a principal engineer on the Citus Cloud team. Citus Data also has an open-source extension to Postgres that distributes database queries horizontally to deliver scale and performance.

WAL-G development is supported by Yandex Cloud

Chat

We have a Slack group and Telegram chat to discuss WAL-G usage and development. To join PostgreSQL slack, use invite app.