Archetype: SE "MicroProfile" metrics as a choice

[tjquinno]

From the public helidon-users slack channel: https://helidon.slack.com/archives/CCS216A5A/p1674059219702039

The user ran helidon init to create a custom SE app, selected yes for observability and yes for metrics.

The user was surprised to be given a choice "MicroProfile" while generating an SE app.

There are at least two potential problems with this:

1. This user was confused to be offers a "MicroProfile" choice for metrics while generating an SE app. It's true that the Helidon SE metrics implementation is heavily inspired by MicroProfile Metrics but it is also incorrect to call it "MicroProfile." It's not an impl of MP metrics.

2. Users might expect that given the two choices that they are two roughly equivalent choices (as with, for example, the JSON library choices offered). That's not the case here.

   The Micrometer work is an integration with Micrometer but that is completely parallel to and separate from Helidon's metrics. Perhaps most importantly, the Helidon-provided metrics are not present in the Micrometer meter registry if the user chooses that.

What would be clearer, I think, would be if the user says yes to metrics then that's it--we add the dependency on helidon-metrics and create and register the metrics service in the generated Java code.

In my mind, it would be fine for users to manually add the Micrometer integration if they want it and not have helidon init ask about Micrometer at all.

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Notes from our group consensus reached on 23 Jan:

We should revise the starter and CLI so that users who choose observability -> metrics will always get the MP metrics-inspired Helidon metrics API and impl. As an option (boolean in Romain's terms) they can also add the Micrometer integration (default = no).

[edbratt]

FWIW, the dependency package is 'helidon-metrics'. Perhaps "Helidon Metrics" is a reasonable title for Quick Start and/or CLI interview. The documentation is clear that the implementation is "... inspired by—​but does not fully implement—​the MicroProfile Metrics specification."

[tjquinno]

Conclusion of discussion:

The archetype should offer Helidon metrics as a yes/no choice.

Micrometer metrics integration should be separate yes/no choice.

Helidon and Micrometer metrics should not be presented as peer choices (i.e., not radio buttons).