Optimize Kafka cluster connections

[pierDipi]

Problem

In our controllers, we often re-create Kafka cluster connections, the original reason was this issue IBM/sarama#2060 . Now, it's fixed we need to re-review our Kafka cluster interactions in the control plane (for all resources) and see if we can optimize them by reducing the number of TCP connections created.

Persona:
Which persona is this feature for?
*

Exit Criteria

Lower number of Kafka connections for a single resource reconciliation

Time Estimate (optional):
How many developer-days do you think this may take to resolve?
7

Additional context (optional)

/kind performance

[pierDipi]

For monitoring and viewing tcp connections for manual testing we could try to use https://www.inspektor-gadget.io/docs/v0.20.0/gadgets/top/tcp/

[Cali0707]

Hey @pierDipi for this issue, are you picturing something like a connection pool now that the connections can re-authenticate without being re-created?

edit: I realized it's more complicated than a simple pool as different connections may need different bootstrap servers and/or config options. I'm going to test:

1. A simple set where whenever a new (bootstrap server, config) pair is used to request a client, a new connection is opened
2. The above with LRU caching to keep max connections < some number

/assign

[pierDipi]

Let's keep in mind that connection pools and caches are very prone to security issues, so let's have a design that reduces the risk of security issues without over-optimizing too early

[Cali0707]

Let's keep in mind that connection pools and caches are very prone to security issues, so let's have a design that reduces the risk of security issues without over-optimizing too early

Do you have some other ideas? My initial really simple idea was to just create one admin client per Reconciler struct that needs one, but I wasn't sure if that would make too many connections overall, and also different brokers may have different bootstrap servers/security combinations which would mean the same client would not work so I thought of the pooling. WDYT @pierDipi ?

[github-actions]

This issue is stale because it has been open for 90 days with no
activity. It will automatically close after 30 more days of
inactivity. Reopen the issue with /reopen. Mark the issue as
fresh by adding the comment /remove-lifecycle stale.

[Cali0707]

/triage accepted
/remove-lifecycle stale