add file locking to prevent concurrent access to Gemfile from plugin manager

Description

Contributor guide

Tech stack

ruby

Domain

backend

Issue type

feature

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

3

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

1-3 hours

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

stale

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

mostly clear

Prerequisites

Ruby basicsUnderstanding of file locking

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

45

Research direction

Refer to the discussion in #2475 for context on the required locking mechanism. Then implement file locking in lib/logstash/gemfile.rb using Ruby's File.flock, ensuring exclusive access. Consider handling lock failures and proper cleanup.