Add Varun Bansal as maintainer

[gbbafna]

I have nominated, and maintainers have agreed to add Varun Bansal (@linuxpi ) as a co-maintainer, who kindly accepted.

Varun is an active contributor of OpenSearch project and is the proposer/developer of Offline Background Tasks and has extensively contributed to Remote Store and Remote Cluster State features which has been launched successfully for users, with most of his recent works focused on offline background task , remote cluster state and remote store related areas. Apart from this, he has proactively contributed to identifying critical bugs, resolving them and improving documentations around the same. Varun is also an active member of the OpenSearch Storage bi-weekly triages and has consistently exercised sound judgement in triaging and prioritizing the issues. Varun has led 3 triages and participated in all storage triages.

Varun, has authored 77 pull requests, reviewed 100 pull requests and created 75 issues in the OpenSearch repo last 12 months, with nearly 15 of them being contributed in the last 3 months. Based on his historical contributions, I am reasonably confident, that Varun will be a valuable addition as a maintainer of OpenSearch and will help to contribute to our success going forward.

Notable Proposals

• Offline Fleet : Separating out background processes to dedicated nodes
  RFC - [RFC] Offline Background Tasks #12361
  Design Proposal - [Design Proposal] Offline Background Tasks #13554
• Shard Level Snapshot Restore - [Feature Request] Shard Level Snapshot Restore #12254
• Drove Remote Cluster State - [META] Remote Cluster State Issues (Phase - 2) #10523
• Remote Store : Performance Improvements , Stats API , Restore API .
  [Meta] Remote Store Performance Improvement #7380
  [RFC] [Remote Store] Remote Store Stats API #7153

Notable Pull-requests

• Offline Fleet
  [Offline Nodes] Adds new library for offline tasks #13574
• Remote Store
  [Remote Store] Add support to remote restore IndexMetadata #9086
  [Remote Store][Refactor] Introduce RemoteStoreRestoreService to handle restore from remote store #9256
  Add support download latest index metadata from remote #9477
  [Remote Store] Add Remote store stats api #7441
  [Remote Store] Add header(codec) and footer(checksum) to remote store segment metadata #5917
• Remote Cluster State
  [Remote Cluster State] Parallel and Multipart IndexMetadata uploads #9664
  Remote Restore Cluster Metadata if local disk state lost after quorum loss recovery #10447
  [Remote Cluster State] Remove stale remote cluster state #9719
• Weighted Round Robin
  Enhance search preference based routing for WRR #6834

Notable Code Reviews

Varun has reviewed close to100 pull requests, helping fellow contributors with meaningful feedback to get them merged

1. Multiple Code Reviews for Remote Cluster state PRs . Some important ones:
   [Remote State] Create service to publish cluster state to remote store #9160
   Upload global cluster state to remote store #10404 and Download functionality of global metadata from remote store #10535
   Split the remote global metadata file to metadata attribute files #12190
2. Permit based Uploads - [Remote Store] Permit backed futures to prevent timeouts during upload bursts #12159
3. Remote Routing Table - [Remote Routing Table] Add write flow for remote routing table #13870
4. Repository Plugin Enhancements - [Remote Store] Add multipart upload integration for translog and segment files #7119 as part of [META] Enhancement of Repository Plugin #6703
5. Remote Segment Backpressure - Add remote refresh segment pressure service, settings and tracker #7227 and [Remote segments] Add backpressure in write path on segments lag between local and remote store #7459 as part of Back pressure for lagging remote segments upload #6851
6. Crypto Plugin to Improve encryption and decryption of content - Core crypto library to perform encryption and decryption of source content #8466 as part of [Design Proposal] Client Side Encryption in OpenSearch #6633
7. Remote Store Repository Registration experience - [Remote Store] Changes to perform repository registration during bootstrap via node attributes. #9105 as part of RFC : Repository Registration for Remote Backed Storage #8623
8. Storage layer improvements - [Remote Store] Add support to provide separate segment metadata repository #12993 and [Feature Request] [Remote Store] Make metadata store independent of data store #12919

Notable Bug finds

1. Race condition in remote store leading to replica failure - [Remote Store] Fix replica failing to download segment files from remote store - NoSuchFileException #11455
2. Deadlock during failover and close - [BUG] Closing an index with ongoing primary failover can lead to deadlocks #11869
3. Segment upload failure in Remote Store when retries are done post errors in upload flow - [BUG] [Remote Store] Segment upload fails with FileAlreadyExistsException  #7388
4. Remote Cluster State
   Cluster chaining breakage : [BUG] [Remote State] Cluster chaining can break if there is consecutive node replace and restart #10841
   Cluster UUID Trimming Logic : [Remote State] Update cluster UUID trimming logic for remote state auto restore flow to compare global metadata #10662
   Restoring decommission attributes after Quorum Loss resulting in election loops : [BUG] [Remote State] Auto restoring decommission attributes after QL can lead to election loops #10905
   Remote state auto restore fails : [BUG] [Remote State] Remote state auto restore fails when process restarts before successful master election. #10776

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
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[gbbafna]

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