rpk fails to connect to an ipv6 admin-api address

[sundbry]

I am running redpanda in an ipv6 only environment, and the admin-api is listening on a private ipv6 address. I attempted to use rpc to show the cluster health.

Version & Environment

Redpanda version: (use rpk version):

rpk version
Version:     v24.1.7
Git ref:     53e6eab6ab
Build date:  2024-06-06T19:49:38Z
OS/Arch:     linux/amd64
Go version:  go1.22.2

What went wrong?

redpanda@redpanda1:/$ rpk cluster health
unable to initialize admin client: invalid host "[[fddb:1e1b:80b7:c98f:c0df:c5d3:8685:4141]]:9644" does not match "host", nor "host:port", nor "scheme://host:port"

What should have happened instead?

The IPv6 compatible host:port should take the form [fddb:1e1b:80b7:c98f:c0df:c5d3:8685:4141]:9644 and rpk should print the cluster health.

How to reproduce the issue?

redpanda.yaml

redpanda:
    data_directory: /var/lib/redpanda/data
    seed_servers: []
    rpc_server:
        address: "fddb:1e1b:80b7:c98f:c0df:c5d3:8685:4141"
        port: 33145
    kafka_api:
        - address: "fddb:1e1b:80b7:c98f:c0df:c5d3:8685:4141"
          port: 9092
    admin:
        - address: "fddb:1e1b:80b7:c98f:c0df:c5d3:8685:4141"
          port: 9644
    advertised_rpc_api:
        address: "fddb:1e1b:80b7:c98f:c0df:c5d3:8685:4141"
        port: 33145
    advertised_kafka_api:
        - address: "fddb:1e1b:80b7:c98f:c0df:c5d3:8685:4141"
          port: 9092
    developer_mode: false
    auto_create_topics_enabled: true
    fetch_reads_debounce_timeout: 10
    group_initial_rebalance_delay: 0
    group_topic_partitions: 3
    log_segment_size_min: 1
    storage_min_free_bytes: 10485760
    topic_partitions_per_shard: 1000
    write_caching_default: "true"
rpk:
    overprovisioned: false
    coredump_dir: /var/lib/redpanda/coredump
pandaproxy:
    pandaproxy_api:
        - address: "fddb:1e1b:80b7:c98f:c0df:c5d3:8685:4141"
          port: 8082
schema_registry:
    schema_registry_api:
        - address: "fddb:1e1b:80b7:c98f:c0df:c5d3:8685:4141"
          port: 8081

JIRA Link: CORE-7340

[matthieugouel]

I have a similar issue by having ipv6 only kafka_api listeners.

  kafka_api:
    - address: 2a06:de00:50:cafe:100::b
      name: dmz
      port: 9092
    - address: 2a06:de00:50:cafe:10::102
      name: backend
      port: 9092

In this case I have:

redpanda@cd0e7641e750:/$ rpk cluster info
unable to initialize kafka client: invalid addr: [[2a06:de00:50:cafe:100::b]]:9092

It does not work either if I put a third listener with an ipv4 address like this:

        - address: 127.0.0.1
          name: local
          port: 9092
        - address: 2a06:de00:50:cafe:100::b
          name: dmz
          port: 9092
        - address: 2a06:de00:50:cafe:10::102
          name: backend
          port: 9092

However redpanda is working correctly, so I guess it is an rpk issue.
To be able to use rpk, I override the broker configuration like this:

rpk -X "brokers=2a06:de00:50:cafe:10::102" cluster info

Hope it helps.

[piyushredpanda]

I don't know if we support ipv6? cc: @twmb

[sundbry]

@piyushredpanda it does.
There is just a bug in the implementation of the configuration where it double-brackets the IP address. The system works fine for IPv6 in all other respects.

[piyushredpanda]

Interesting data point, @sundbry. @mattschumpert and @twmb could perhaps then look into the rpk bits. cc: @r-vasquez too