Kong: Kong rate-limtiing plugin is not setting ttl to some keys when using redis

[vasuharish]

Summary

When tested Kong's rate-limiting plugin with redis config, found Kong is not setting TTLs for all the keys, some of the keys are having -1 ttl which is increasing the data in redis and slowing the repsonse from redis server.

Why the issue is happening:
During the increment we are checking whether the key exists in the redis or not and only setting the ttl if the key is not present in the redis.
https://github.com/Kong/kong/blob/master/kong/plugins/rate-limiting/policies/init.lua#L177

Steps To Reproduce

1. Start Kong with 16 worker threads
2. Configure rate-limiting plugin redis
3. Make parallel calls ( I have tested using apache bench mark ab -n 10000 -c 20 http://127.0.0.1:8000/testapi

Additional Details & Logs

• Kong version 1.2.2 ( but the plugin logic is same for 2.0.2 also)

[bungle]

Yes, we should make that a redis function.

[vasuharish]

We can create a pr to fix this issue along with redis sentinel support in rate-limiting. Our team has ran performance tests with different configurations on rate-limiting plugin, we can also share those results along with PR.

[bungle]

@vasuharish, sound like a plan! I am glad to review such PR! Bring it on ;-)!

[vasuharish]

Hi @bungle , created PR for the fix, can you please take a look at the PR. thank you