After 4.2.0 migration, using ioredis, you must force IPv6 resolution for the streaming API

[AlyxPractice]

Steps to reproduce the problem

Following the migration to ioredis (#26581) I had connection issues to my Redis instance on fly.io, using IPv6.

I was using :

REDIS_HOST = "my-instance-redis.internal"
REDIS_PORT = "6379"

But now I need to force the IPv6 resolution using the family parameter :

REDIS_URL = "redis://my-instance-redis.internal:6379/?family=6"

I found some occurrences of this parameter here and there:

• https://github.com/redis/ioredis/blob/ec42c82ceab1957db00c5175dfe37348f1856a93/test/unit/utils.ts#L198-L205
• https://github.com/redis/ioredis/blob/ec42c82ceab1957db00c5175dfe37348f1856a93/lib/utils/index.ts#L241-L246

Maybe we could add a warning to the administrator in the changelog about that? Ideally, a way to resolve the hostname, no matter if it's IPv4 or IPv6 on top of their library would be super cool to avoid any issues like this.

I'm creating this issue to help others mostly if they spot something similar.

Expected behaviour

ioredis library should do the hostname IPv6 resolution "natively"

Actual behaviour

ioredis failed to connect to IPv6 Redis instances, except if you force it using the family parameter in REDIS_URL

Detailed description

No response

Mastodon instance

3615.computer

Mastodon version

v4.2.0

Technical details

If this is happening on your own Mastodon server, please fill out those:

• Ruby version: v3.2.2p53
• Node.js version: v20.6.1

I did not save the log showing the issue, but from my search history it was something like Error: getaddrinfo ENOTFOUND.

[vmstan]

Does this impact the regular Mastodon process connections to Redis as well or just for the streaming API?

[AlyxPractice]

Does this impact the regular Mastodon process connections to Redis as well or just for the streaming API?

Sidekiq was in a working state so it seems to only impact the streaming API.

[AlyxPractice]

I'll try to write some code to easily reproduce the issue and eventually make a PR here or on ioredis. ioredis seems to use https://nodejs.org/api/dns.html#dnslookuphostname-options-callback under the hood.

[ThisIsMissEm]

@VictorBersy I think you'd be better filing this as an upstream issue in ioredis: https://github.com/redis/ioredis/issues

By default ioredis assumes IPv4, per https://github.com/redis/ioredis/blob/main/lib/redis/RedisOptions.ts#L192, when it should probably not assume IPv4 (by passing 0 for the family instead of 4)