redis-py-cluster

This client provides a client for redis cluster that was added in redis 3.0.

This project is a port of redis-rb-cluster by antirez, with a lot of added functionality. The original source can be found at https://github.com/antirez/redis-rb-cluster

The branch master will always contain the latest unstable/development code that has been merged from Pull Requests. Use the latest commit from master branch on your own risk, there is no guarantees of compatibility or stability of non tagged commits on the master branch. Only tagged releases on the master branch is considered stable for use.

Python 2 Compatibility Note

This library follows the announced change from our upstream package redis-py. Due to this, we will follow the same python 2.7 deprecation timeline as stated in there.

redis-py-cluster 2.1.x will be the last major version release that supports Python 2.7. The 2.1.x line will continue to get bug fixes and security patches that support Python 2 until August 1, 2020. redis-py-cluster 3.0.x will be the next major version and will require Python 3.5+.

Documentation

All documentation can be found at https://redis-py-cluster.readthedocs.io/en/master

This Readme contains a reduced version of the full documentation.

Upgrading instructions between each released version can be found here

Changelog for next release and all older releases can be found here

Installation

Latest stable release from pypi

$ pip install redis-py-cluster

This major version of redis-py-cluster supports redis-py >=3.0.0, <4.0.0.

Usage example

Small sample script that shows how to get started with RedisCluster. It can also be found in examples/basic.py

>>> from rediscluster import RedisCluster

>>> # Requires at least one node for cluster discovery. Multiple nodes is recommended.
>>> startup_nodes = [{"host": "127.0.0.1", "port": "7000"}, {"host": "127.0.0.1", "port": "7001"}]
>>> rc = RedisCluster(startup_nodes=startup_nodes, decode_responses=True)

# Or you can use the simpler format of providing one node same way as with a Redis() instance
<<< rc = RedisCluster(host="127.0.0.1", port=7000, decode_responses=True)

>>> rc.set("foo", "bar")
True
>>> print(rc.get("foo"))
'bar'

License & Authors

Copyright (c) 2013-2021 Johan Andersson

MIT (See docs/License.txt file)

The license should be the same as redis-py (https://github.com/andymccurdy/redis-py)

Release Notes

2.1.3 (Apr 24 2021)

* Add example script pipelin-readonly-replica.py to show how to use replica nodes to offload read commands from primary node
* max_connection now defaults to 50 in ClusterBlockingConnectionPool to avoid issue with infinite loop in queue mechanism
* Using read replica for read commands inside pipeline is now better supported. Feature might be unstable to use as own risk.
* Fixed that in some cases where ConnectionError is raised, a non existing connection was attempted to be disconnected and caused a sub exception to be raised.

2.1.2 (Apr 18 2021)

* Fixed bug where "from rediscluster import *" would not work correct

2.1.1 (Apr 18 2021)

* ClusterPipeline is now exposed when doing "from rediscluster import *"
* Fix issue where connection would be None in some cases when connection pool fails to initialize
* Ported in a fix from redis-py where it now checks if a connection is ready or not before returning the connection for usage
* ClusterFailover command option is no longer mandatory but optional as it is intended
* Fixed "SLOWLOG GET" kwarg command where it failed on decode_responses
* BaseException is now caught when executing commands and it will disconnect and the connection before raising the exception.
* Logging exception on ReseponseError when doing the initial connection to the startup_nodes instances

2.1.0 (Sept 26, 2020)

* Add new config option for Client and Pipeline classes to controll how many attempts will be made before bailing out from a ClusterDownError.
  Use "cluster_down_retry_attempts=<int>" when creating the client class to controll this behaviour.
* Updated redis-py compatbile version to support any version in the major version 3.0.x, 3.1.x, 3.2.x, 3.3.x., 3.4.x, 3.5.x (#326)
  It is always recommended to use the latest version of redis-py to avoid issues and compatiblity problems.
* Fixed bug preventing reinitialization after getting MOVED errors
* Add testing of redis-esrver 6.0 versions to travis and unit tests
* Add python 2.7 compatiblity note about deprecation and upcomming changes in python 2.7 support for this lib
* Updated tests and cluster tests versions of the same methods to latest tests from upstream redis-py package
* Reorganized tests and how cluster specific tests is written and run over the upstream version of the same test to make it easier
  and much faster to update and keep them in sync over time going into the future (#368)
* Python 3.5.x or higher is now required if running on a python 3 version
* Removed the monkeypatching of RedisCluster, ClusterPubSub & ClusterPipeline class names into the "redis" python package namespace during runtime.
  They are now exposed in the "rediscluster" namespace to mimic the same feature from redis-py
* cluster_down_retry_attempts can now be configured to any value when creating RedisCluster instance
* Creating RedisCluster from unix socket url:s has been disabled
* Patch the from_url method to use the corret cluster version of the same Connection class
* ConnectionError and TimeoutError is now handled seperately in the main execute loop to better handle each case (#363)
* Update scan_iter custom cluster implementation
* Improve description_format handling for connection classes to simplify how they work
* Implement new connection pool ClusterBlockingConnectionPool (#347)
* Nodemanager initiailize should now handle usernames properly (#365)
* PubSub tests has been all been disabled
* New feature, host_port_remap. Send in a remapping configuration to RedisCluster instance where the nodes configuration recieved from the redis cluster can be altered to allow for connection in certain circumstances. See new section in client.rst in docs/ for usage example.
* When a slot is not covered by the cluster, it will not raise SlotNotCoveredError instead of the old generic RedisClusterException. The client will not attempt to rebuild the cluster layout a few times before giving up and raising that exception to the user. (#350)
* CLIENT SETNAME is now possible to use from the client instance. For setting the name for all connections from the client by default, see issue #802 in redis-py repo for the change that was implemented in redis-py 3.4.0.
* Rewrote implemented commands documentation to mimic the redis.io commands documentation and describe each command and any additional implementation that has been made.
* Added RTD theme to the rendered output when running the documentation in local dev mode. 
* Added some basic logging to the client that should make it easier to debug and track down minor issues around the main execution loop. See docs/logging.rst for implementation example into your own code.
* Seperated some of the exception handling inside the main execution loop to get more fine grained controll what to do at certain errors.

2.0.0 (Aug 12, 2019)

Specific changes to redis-py-cluster is mentioned below here.

* Update entire code base to now support all redis-py version in the 3.0.x version line. Any future redis-py version will be supported at a later time.
* Major update to all tests to mirror the code of the same tests from redis-py
* Dropped support for the 2.10.6 redis-py release.
* Add pythoncodestyle lint validation check to travis-ci runs to check for proper linting before accepting PR:s
* Class StrictRedisCluster was renamed to RedisCluster
* Class StrictRedis has been removed to mirror upstream class structure
* Class StrictClusterPipeline was renamed to ClusterPipeline
* Fixed travis-ci tests not running properly on python 3.7
* Fixed documentation regarding threads in pipelines
* Update lit of command callbacks and parsers. Added in "CLIENT ID"
* Removed custom implementation of SORT and revert back to use same-slot mechanism for that command.
* Added better exception message to get_master_node_by_slot command to help the user understand the error.
* Improved the exception object message parsing when running on python3

1.3.6 (Nov 16, 2018)

* Pin upstream redis-py package to release 2.10.6 to avoid issues with incompatible version 3.0.0

1.3.5 (July 22, 2018)

* Add Redis 4 compatability fix to CLUSTER NODES command (See issue #217)
* Fixed bug with command "CLUSTER GETKEYSINSLOT" that was throwing exceptions
* Added new methods cluster_get_keys_in_slot() to client
* Fixed bug with `StrictRedisCluster.from_url` that was ignoring the `readonly_mode` parameter
* NodeManager will now ignore nodes showing cluster errors when initializing the cluster
* Fix bug where RedisCluster wouldn't refresh the cluster table when executing commands on specific nodes
* Add redis 5.0 to travis-ci tests
* Change default redis version from 3.0.7 to 4.0.10
* Increase accepted ranges of dependencies specefied in dev-requirements.txt
* Several major and minor documentation updates and tweaks
* Add example script "from_url_password_protected.py"
* command "CLUSTER GETKEYSINSLOT" is now returned as a list and not int
* Improve support for ssl connections
* Retry on Timeout errors when doing cluster discovery
* Added new error class "MasterDownError"
* Updated requirements for dependency of redis-py to latest version

1.3.4 (Mar 5, 2017)

* Package is now built as a wheel and source package when releases is built.
* Fixed issues with some key types in `NodeManager.keyslot()`.
* Add support for `PUBSUB` subcommands `CHANNELS`, `NUMSUB [arg] [args...]` and `NUMPAT`.
* Add method `set_result_callback(command, callback)` allowing the default reply callbacks to be changed, in the same way `set_response_callback(command, callback)` inherited from Redis-Py does for responses.
* Node manager now honors defined max_connections variable so connections that is emited from that class uses the same variable.
* Fixed a bug in cluster detection when running on python 3.x and decode_responses=False was used.
  Data back from redis for cluster structure is now converted no matter what the data you want to set/get later is using.
* Add SSLClusterConnection for connecting over TLS/SSL to Redis Cluster
* Add new option to make the nodemanager to follow the cluster when nodes move around by avoiding to query the original list of startup nodes that was provided
  when the client object was first created. This could make the client handle drifting clusters on for example AWS easier but there is a higher risk of the client talking to
  the wrong group of nodes during split-brain event if the cluster is not consistent. This feature is EXPERIMENTAL and use it with care.

1.3.3 (Dec 15, 2016)

* Remove print statement that was faulty commited into release 1.3.2 that case logs to fill up with unwanted data.

1.3.2 (Nov 27, 2016)

* Fix a bug where from_url was not possible to use without passing in additional variables. Now it works as the same method from redis-py.
  Note that the same rules that is currently in place for passing ip addresses/dns names into startup_nodes variable apply the same way through
  the from_url method.
* Added options to skip full coverage check. This flag is useful when the CONFIG redis command is disabled by the server.
* Fixed a bug where method *CLUSTER SLOTS* would break in newer redis versions where node id is included in the reponse. Method is not compatible with both old and new redis versions.

1.3.1 (Oct 13, 2016)

* Rebuilt broken method scan_iter. Previous tests was to small to detect the problem but is not corrected to work on a bigger dataset during the test of that method. (korvus81, Grokzen, RedWhiteMiko)
* Errors in pipeline that should be retried, like connection errors, moved, errors and ask errors now fall back to single operation logic in StrictRedisCluster.execute_command. (72squared).
* Moved reinitialize_steps and counter into nodemanager so it can be correctly counted across pipeline operations (72squared).

1.3.0 (Sep 11, 2016)

* Removed RedisClusterMgt class and file
* Fixed a bug when using pipelines with RedisCluster class (Ozahata)
* Bump redis-server during travis tests to 3.0.7
* Added docs about same module name in another python redis cluster project.
* Fix a bug when a connection was to be tracked for a node but the node either do not yet exists or
  was removed because of resharding was done in another thread. (ashishbaghudana)
* Fixed a bug with "CLUSTER ..." commands when a node_id argument was needed and the return type
  was supposed to be converted to bool with bool_ok in redis._compat.
* Add back gitter chat room link
* Add new client commands
  - cluster_reset_all_nodes
* Command cluster_delslots now determines what cluster shard each slot is on and sends each slot deletion
  command to the correct node. Command have changed argument spec (Read Upgrading.rst for details)
* Fixed a bug when hashing the key it if was a python 3 byte string and it would cause it to route to wrong slot in the cluster (fossilet, Grokzen)
* Fixed a bug when reinitialize the nodemanager it would use the old nodes_cache instead of the new one that was just parsed (monklof)

1.2.0 (Apr 09, 2016)

* Drop maintained support for python 3.2.
* Remove Vagrant file in favor for repo maintained by 72squared
* Add Support for password protected cluster (etng)
* Removed assertion from code (gmolight)
* Fixed a bug where a regular connection pool was allocated with each StrictRedisCluster instance.
* Rework pfcount to now work as expected when all arguments points to same hashslot
* New code and important changes from redis-py 2.10.5 have been added to the codebase.
* Removed the need for threads inside of pipeline. We write the packed commands all nodes before reading the responses which gives us even better performance than threads, especially as we add more nodes to the cluster.
* Allow passing in a custom connection pool
* Provide default max_connections value for ClusterConnectionPool *(2**31)*
* Travis now tests both redis 3.0.x and 3.2.x
* Add simple ptpdb debug script to make it easier to test the client
* Fix a bug in sdiffstore (mt3925)
* Fix a bug with scan_iter where duplicate keys would be returned during itteration
* Implement all "CLUSTER ..." commands as methods in the client class
* Client now follows the service side setting 'cluster-require-full-coverage=yes/no' (baranbartu)
* Change the pubsub implementation (PUBLISH/SUBSCRIBE commands) from using one single node to now determine the hashslot for the channel name and use that to connect to
  a node in the cluster. Other clients that do not use this pattern will not be fully compatible with this client. Known limitations is pattern
  subscription that do not work properly because a pattern can't know all the possible channel names in advance.
* Convert all docs to ReadTheDocs
* Rework connection pool logic to be more similar to redis-py. This also fixes an issue with pubsub and that connections
  was never release back to the pool of available connections.

1.1.0 (Oct 27, 2015)

* Refactored exception handling and exception classes.
* Added READONLY mode support, scales reads using slave nodes.
* Fix __repr__ for ClusterConnectionPool and ClusterReadOnlyConnectionPool
* Add max_connections_per_node parameter to ClusterConnectionPool so that max_connections parameter is calculated per-node rather than across the whole cluster.
* Improve thread safty of get_connection_by_slot and get_connection_by_node methods (iandyh)
* Improved error handling when sending commands to all nodes, e.g. info. Now the connection takes retry_on_timeout as an option and retry once when there is a timeout. (iandyh)
* Added support for SCRIPT LOAD, SCRIPT FLUSH, SCRIPT EXISTS and EVALSHA commands. (alisaifee)
* Improve thread safety to avoid exceptions when running one client object inside multiple threads and doing resharding of the
  cluster at the same time.
* Fix ASKING error handling so now it really sends ASKING to next node during a reshard operation. This improvement was also made to pipelined commands.
* Improved thread safety in pipelined commands, along better explanation of the logic inside pipelining with code comments.

1.0.0 (Jun 10, 2015)

* No change to anything just a bump to 1.0.0 because the lib is now considered stable/production ready.

0.3.0 (Jun 9, 2015)

* simple benchmark now uses docopt for cli parsing
* New make target to run some benchmarks 'make benchmark'
* simple benchmark now support pipelines tests
* Renamed RedisCluster --> StrictRedisCluster
* Implement backwards compatible redis.Redis class in cluster mode. It was named RedisCluster and everyone updating from 0.2.0 to 0.3.0 should consult docs/Upgrading.md for instructions how to change your code.
* Added comprehensive documentation regarding pipelines
* Meta retrieval commands(slots, nodes, info) for Redis Cluster. (iandyh)

0.2.0 (Dec 26, 2014)

* Moved pipeline code into new file.
* Code now uses a proper cluster connection pool class that handles
  all nodes and connections similar to how redis-py do.
* Better support for pubsub. All clients will now talk to the same server because
  pubsub commands do not work reliably if it talks to a random server in the cluster.
* Better result callbacks and node routing support. No more ugly decorators.
* Fix keyslot command when using non ascii characters.
* Add bitpos support, redis-py 2.10.2 or higher required.
* Fixed a bug where vagrant users could not build the package via shared folder.
* Better support for CLUSTERDOWN error. (Neuront)
* Parallel pipeline execution using threads. (72squared)
* Added vagrant support for testing and development. (72squared)
* Improve stability of client during resharding operations (72squared)

0.1.0 (Sep 29, 2014)

* Initial release
* First release uploaded to pypi