rpk: mode production set group partitions to be greater than 1

[emaxerrno]

https://github.com/vectorizedio/redpanda/blob/dev/src/v/config/configuration.cc#L363-L368

Should be set to 16 or 32 or smth like that when doing rpk mode production on the command line.

@dotnwat - does it use the default replication factor or how does it know what's the default replication factor?

[emaxerrno]

basically something like this in the rpk config - though i'm not sure we expose all of these settings.

offsets.topic.num.partitions=16
offsets.topic.replication.factor=3
offsets.commit.required.acks=-1

[twmb]

Isn't the default for redpanda now to have 3 nodes if the cluster grows to a size of 3? cc @jcsp

[jcsp]

I think this ticket is about partition counts rather than replication factor (i.e. group_topic_partitions)

[mmedenjak]

I guess this is related - #5412 (we bumped the default already for 22.2).

[twmb]

Depends on #5661

[twmb]

group_topic_partitions now defaults to 16, so we no longer need to change this from rpk between dev & prod mode.

https://github.com/redpanda-data/redpanda/blob/dev/src/go/rpk/pkg/cli/cmd/redpanda/start.go#L1041-L1044

This is also now a cluster configuration (i.e. changed since this issue was created).

I think that since 16 is a fine default (as per the suggestion in the issue description), this is done per #5412.