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
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.
WAL-G supports bash and zsh autocompletion. Run wal-g help completion for more info.
To configure where WAL-G stores backups, please consult the Storages section.
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.
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. libsodium keys are fixed-size keys of 32 bytes. For optimal cryptographic security, it is recommened to use a random 32 byte key. To generate a random key, you can something like openssl rand -hex 32 (set WALG_LIBSODIUM_KEY_TRANSFORM to hex) or openssl rand -base64 32 (set WALG_LIBSODIUM_KEY_TRANSFORM to base64).
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_LIBSODIUM_KEY_TRANSFORM
The transform that will be applied to the WALG_LIBSODIUM_KEY to get the required 32 byte key. Supported transformations are base64, hex or none (default).
The option none exists for backwards compatbility, the user input will be converted to 32 byte either via truncation or by zero-padding.
WALG_GPG_KEY_ID(alternative formWALE_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.
WALG_STATSD_ADDRESS
To enable metrics publishing to statsd or statsd_exporter. Metrics will be sent on a best-effort basis via UDP. The default port for statsd is 9125.
Profiling is useful for identifying bottlenecks within WAL-G.
PROFILE_SAMPLING_RATIO
A float value between 0 and 1, defines likelihood of the profiler getting enabled. When set to 1, it will always run. This allows probabilistic sampling of invocations. Since WAL-G processes may get created several times per second (e.g. wal-g wal-push), we do not want to profile all of them.
PROFILE_MODE
The type of pprof profiler to use. Can be one of cpu, mem, mutex, block, threadcreation, trace, goroutine. See the runtime/pprof docs for more information. Defaults to cpu.
PROFILE_PATH
The directory to store profiles in. Defaults to $TMPDIR.
More options are available for the chosen database. See it in Databases
WAL-G currently supports these commands for all type of databases:
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
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
%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.
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
wal-g st command series allows the direct interaction with the configured storage.
Storage tools documentation
Information about installing, configuration and usage
Information about installing, configuration and usage
Information about installing, configuration and usage
Information about installing, configuration and usage
Information about installing, configuration and usage
Information about installing, configuration and usage
Information about installing, configuration and usage
It is specified for your type of database.
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 unittestFor 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 coverageThis command generates coverage.out file and opens HTML representation of the coverage.
Information about installing and usage
See also the list of contributors who participated in this project.
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.
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
We have a Slack group and Telegram chat to discuss WAL-G usage and development. To join PostgreSQL slack, use invite app.