Avi Kivity 78104f93ac Merge '[Backport 2025.3] Introduce TTL and retries to address resolution' from Scylladb[bot]
In production environments, we observed cases where the S3 client would repeatedly fail to connect due to DNS entries becoming stale. Because the existing logic only attempted the first resolved address and lacked a way to refresh DNS state, the client could get stuck in a failure loop.

Introduce RR TTL and connection failure retry to
- re-resolve the RR in a timely manner
- forcefully reset and re-resolve addresses
- add a special case when the TTL is 0 and the record must be resolved for every request

Fixes: CUSTOMER-96
Fixes: CUSTOMER-139

Should be backported to 2025.3/4 and 2026.1 since we already encountered it in the production clusters for 2025.3

- (cherry picked from commit bd9d5ad75b)

- (cherry picked from commit 359d0b7a3e)

- (cherry picked from commit ce0c7b5896)

- (cherry picked from commit 5b3e513cba)

- (cherry picked from commit 66a33619da)

- (cherry picked from commit 6eb7dba352)

- (cherry picked from commit a05a4593a6)

- (cherry picked from commit 3a31380b2c)

- (cherry picked from commit 912c48a806)

Parent PR: #27891

Closes scylladb/scylladb#28403

* github.com:scylladb/scylladb:
  connection_factory: includes cleanup
  dns_connection_factory: refine the move constructor
  connection_factory: retry on failure
  connection_factory: introduce TTL timer
  connection_factory: get rid of shared_future in dns_connection_factory
  connection_factory: extract connection logic into a member
  connection_factory: remove unnecessary `else`
  connection_factory: use all resolved DNS addresses
  s3_test: remove client double-close
2026-02-05 13:10:46 +02:00
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2026-02-01 05:09:04 +02:00
2025-04-12 11:28:48 +03:00
2025-03-04 09:45:23 +02:00
2025-09-01 09:10:41 +03:00
2025-10-28 13:10:12 +03:00
2025-06-30 07:24:05 +03:00
2025-02-11 00:17:43 +02:00
2025-06-14 21:29:43 +03:00
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2025-01-15 11:10:35 +01:00

Scylla

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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++23 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:

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

Build with the latest Seastar Check Reproducible Build clang-nightly

See test.py manual.

Scylla APIs and compatibility

By default, Scylla is compatible with Apache Cassandra and its API - CQL. 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 ScyllaDB.
  • The developers mailing list is for developers and people interested in following the development of ScyllaDB to discuss technical topics.
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