50ebce8acc
When a node changes IP address we need to remove its old IP from `system.peers` and gossiper. We do this in `sync_raft_topology_nodes` when the new IP is saved into `system.peers` to avoid losing the mapping if the node crashes between deleting and saving the new IP. We also handle the possible duplicates in this case by dropping them on the read path when the node is restarted. The PR also fixes the problem with old IPs getting resurrected when a node changes its IP address. The following scenario is possible: a node `A` changes its IP from `ip1` to `ip2` with restart, other nodes are not yet aware of `ip2` so they keep gossiping `ip1`. After restart `A` receives `ip1` in a gossip message and calls `handle_major_state_change` since it considers it as a new node. Then `on_join` event is called on the gossiper notification handlers, we receive such event in `raft_ip_address_updater` and reverts the IP of the node A back to ip1. To fix this we ensure that the new gossiper generation number is used when a node registers its IP address in `raft_address_map` at startup. The `test_change_ip` is adjusted to ensure that the old IPs are properly removed in all cases, even if the node crashes. Fixes #16886 Fixes #16691 Fixes #17199 Closes scylladb/scylladb#17162 * github.com:scylladb/scylladb: test_change_ip: improve the test raft_ip_address_updater: remove stale IPs from gossiper raft_address_map: add my ip with the new generation system_keyspace::update_peer_info: check ep and host_id are not empty system_keyspace::update_peer_info: make host_id an explicit parameter system_keyspace::update_peer_info: remove any_set flag optimisation system_keyspace: remove duplicate ips for host_id system_keyspace: peers table: use coroutines storage_service::raft_ip_address_updater: log gossiper event name raft topology: ip change: purge old IP on_endpoint_change: coroutinize the lambda around sync_raft_topology_nodes
Scylla
What is Scylla?
Scylla is the real-time big data database that is API-compatible with Apache Cassandra and Amazon DynamoDB. Scylla embraces a shared-nothing approach that increases throughput and storage capacity to realize order-of-magnitude performance improvements and reduce hardware costs.
For more information, please see the ScyllaDB web site.
Build Prerequisites
Scylla is fairly fussy about its build environment, requiring very recent versions of the C++20 compiler and of many libraries to build. The document HACKING.md includes detailed information on building and developing Scylla, but to get Scylla building quickly on (almost) any build machine, Scylla offers a frozen toolchain, This is a pre-configured Docker image which includes recent versions of all the required compilers, libraries and build tools. Using the frozen toolchain allows you to avoid changing anything in your build machine to meet Scylla's requirements - you just need to meet the frozen toolchain's prerequisites (mostly, Docker or Podman being available).
Building Scylla
Building Scylla with the frozen toolchain dbuild is as easy as:
$ git submodule update --init --force --recursive
$ ./tools/toolchain/dbuild ./configure.py
$ ./tools/toolchain/dbuild ninja build/release/scylla
For further information, please see:
- Developer documentation for more information on building Scylla.
- Build documentation on how to build Scylla binaries, tests, and packages.
- Docker image build documentation for information on how to build Docker images.
Running Scylla
To start Scylla server, run:
$ ./tools/toolchain/dbuild ./build/release/scylla --workdir tmp --smp 1 --developer-mode 1
This will start a Scylla node with one CPU core allocated to it and data files stored in the tmp directory.
The --developer-mode is needed to disable the various checks Scylla performs at startup to ensure the machine is configured for maximum performance (not relevant on development workstations).
Please note that you need to run Scylla with dbuild if you built it with the frozen toolchain.
For more run options, run:
$ ./tools/toolchain/dbuild ./build/release/scylla --help
Testing
See test.py manual.
Scylla APIs and compatibility
By default, Scylla is compatible with Apache Cassandra and its APIs - CQL and Thrift. There is also support for the API of Amazon DynamoDB™, which needs to be enabled and configured in order to be used. For more information on how to enable the DynamoDB™ API in Scylla, and the current compatibility of this feature as well as Scylla-specific extensions, see Alternator and Getting started with Alternator.
Documentation
Documentation can be found here. Seastar documentation can be found here. User documentation can be found here.
Training
Training material and online courses can be found at Scylla University. The courses are free, self-paced and include hands-on examples. They cover a variety of topics including Scylla data modeling, administration, architecture, basic NoSQL concepts, using drivers for application development, Scylla setup, failover, compactions, multi-datacenters and how Scylla integrates with third-party applications.
Contributing to Scylla
If you want to report a bug or submit a pull request or a patch, please read the contribution guidelines.
If you are a developer working on Scylla, please read the developer guidelines.
Contact
- The community forum and Slack channel are for users to discuss configuration, management, and operations of the ScyllaDB open source.
- The developers mailing list is for developers and people interested in following the development of ScyllaDB to discuss technical topics.