Flink 2.1: add EtcdLockFactory implementation.

[slfan1989]

Motivation

Iceberg currently supports JdbcLock and ZkLock as distributed lock backends. With the growing adoption of Flink on Kubernetes, it is increasingly important to support a lock mechanism that aligns well with cloud-native environments.

Etcd is widely used in Kubernetes ecosystems (as the backing store of Kubernetes itself) and is implemented based on the Raft consensus algorithm, which provides strong consistency and fault tolerance. Compared to Zookeeper, Etcd typically offers simpler operations and better performance in Raft-based consensus scenarios.

Adding an EtcdLockFactory will provide users with an additional, cloud-native friendly option for distributed lock management in Flink jobs running on Kubernetes.

Changes

• Introduce EtcdLockFactory implementation in the Flink lock module.
• Add configuration options for Etcd client connection (URI, connection timeout, keepalive, retries, etc.).
• Provide integration with Iceberg’s existing lock abstraction.
• Add tests using jetcd-launcher to verify Etcd-based lock behavior.

Usage

Users can enable Etcd-based locks in Flink by configuring:

iceberg.lock.impl=etcd
iceberg.lock.etcd.uri=http://127.0.0.1:2379
iceberg.lock.etcd.connection-timeout-ms=5000
iceberg.lock.etcd.keepalive-ms=30000
iceberg.lock.etcd.keepalive-timeout-ms=10000
iceberg.lock.etcd.max-retries=2

etcd versus other key-value stores

[slfan1989]

@pvary @mxm I’ve added a new lock implementation that uses etcd as a distributed lock. Could you please help review this PR? Thanks a lot!

[pvary]

Cc: @Guosmilesmile

[slfan1989]

@Guosmilesmile @pvary Could we continue to move forward with this pr? I would really appreciate your help. Thank you so much!

[Guosmilesmile]

@slfan1989 Sorry, I’ve been quite busy lately. I’ll find some time to continue the review soon. Thank you!

[slfan1989]

@Guosmilesmile When you have a moment, Could you please take another look at this PR? I really appreciate your time and help!

cc: @pvary

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