spring-cloud/spring-cloud-gateway

Introduce Logging when reactiveScriptExecutor.eval returns flux.error

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#886 opened on Mar 8, 2019

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enhancementhelp wanted

Description

In order to determine that the target Redis services does not have lua scripts enabled, the flux.error should returned by the reactiveScriptExecutor.eval [1], should be shown to the developer maybe through logging when flux.onErrorResume is invoked in the RedisRateLimiter [2].

Spring Cloud version: Greenwich.RELEASE Spring Boot version: 2.1.3.RELEASE

We found this in an Pivotal Application Services environment where the Redis data services 2.0.1 is deployed. Through debugging it would found that the plan being used had not enabled Lua Scripting.

image

The solution was to enable Lua Scripting for the plan and apply the change to all redis service instances using that plan.

This was difficult to troubleshoot because the only way we found to determine why the rate limiting rules were not being enforced was to set a debug break point in thereactiveScriptExecutor [1] which caught the exception with the following message:

org.springframework.data.redis.RedisSystemException: Error in execution; nested exception is io.lettuce.core.RedisCommandExecutionException: ERR unknown command `EVALSHA`, with args beginning with: `eec77786d43c65f7fd568900b5d2b63b692318dc`, `2`, `request_rate_limiter.{user}.tokens`, `request_rate_limiter.{user}.timestamp`,

What would really help us out is if their was logging when the exception was encounter or if when spring cloud gateway starts up we could have some sort of warning that the scripting capability is not enabled therefore rate limiting will not be enforced? We are open to any other ideas or suggestions on how to troubleshoot this to remember for next time since this was our first pass with the spring cloud gateway.

[1] https://github.com/spring-projects/spring-data-redis/blob/2.1.x/src/main/java/org/springframework/data/redis/core/script/DefaultReactiveScriptExecutor.java#L121-L122 [2] https://github.com/spring-cloud/spring-cloud-gateway/blob/2.1.x/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/ratelimit/RedisRateLimiter.java#L228

Contributor guide

Tech stack
javaspringredis
Domain
backendobservability
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.
half day
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.
clear
Prerequisites
JavaSpring BootReactive streamsRedis
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
Investigate the suggested code locations in DefaultReactiveScriptExecutor.java (line 121-122) and RedisRateLimiter.java (line 228). Determine where to add logging to capture the error message when reactiveScriptExecutor.eval returns a flux.error. Consider using appropriate log levels (e.g., ERROR or WARN) and ensure the log message includes the error details for easier debugging. Check for any existing logging patterns in the codebase. Also, review the discussion in the issue comments for any additional insights.