It would be better to consolidate all information into a single message. This is because the four lines are not guaranteed to appear consecutively in the logs.

1. Would it make sense to define and maintain a set of Micrometer metrics and increment them here?
2. Would it make sense to fire a PolarisEvent here?

(I don't really know what an IRC server is supposed to do with these scan or commit metrics 😅)

I'm not sure what those are 😅 my intentions were to have the default behaviour remain the same, and adding that may change the default behaviour

😄 - no worries, we can look into that later.

Iceberg already has a MetricsReporter and a LoggingMetricsReporter. I suppose you created new ones because you wanted to pass the warehouse and namespace names as well? In this case would it be possible to extend Iceberg's MetricsReporter?

So that was my original plan! But the iceberg MetricsReporter is intended for client-side operations, so implementing it won't suffice for the /metrics endpoint reporting.

It would be ideal to change the name of it so that it doesn't get confused, but I wasn't sure of a better name 😅

I see. Would something like this suit your needs?

public interface PolarisMetricsReporter extends MetricsReporter {
 void report(String catalog, TableIdentifier table, MetricsReport report);
}

the iceberg implementation is definitely not what we want to extend/implement here - https://iceberg.apache.org/docs/1.10.0/docs/metrics-reporting

it's a client side thing. but I can change the name of this interface to PolarisMetricsReporter to have that separation.

1. I would rather rename prefix to warehouse or catalogName since prefix is a REST-specific notion.
   1. But you should to call prefixParser.prefixToCatalogName(realmContext, prefix) to get the catalog name from the prefix.
2. For a richer API, I would use TableIdentifier rather than 2 strings (namespace + table). It's very easy to get a TableIdentifier:

   Namespace ns = decodeNamespace(namespace);
   TableIdentifier tableIdentifier = TableIdentifier.of(ns, RESTUtil.decodeString(table));

I forgot: it's probably better to pass MetricsReport here, not ReportMetricsRequest.

These tests are rather useless as they are basically testing SmallRye Config.

What would be more meaningful is a real test that invokes the IRC metrics endpoint and verifies that metrics were collected.

I'm not sure we need a distinct logging reporter. The default reporter could log the metrics, then users could simply adjust their log levels and decide whether they want the metrics to appear in the logs or not (by default, they wouldn't be logged). WDYT?

config.type() is fixed in runtime... Can this bean be @ApplicationScoped?