[FR] CLI function to check a cluster for Deprecated Rules

[w0rk3r]

Repository Feature

Core Repo - (rule management, validation, testing, lib, cicd, etc.)

Problem Description

Long-time customers might still be running deprecated rules without realizing that the logic is either not performant or flawed.

Desired Solution

We could provide a CLI command to check the cluster for rules that are in https://github.com/elastic/detection-rules/blob/main/detection_rules/etc/deprecated_rules.json

Here is a quick (and dirty) check in python I did for a customer: https://gist.github.com/w0rk3r/01196baf3449d4f1605337aa497c0e7a

Considered Alternatives

No response

Additional Context

• Slack thread for context

[richlv]

Somewhat related to #2327 .