I would like to get some opinions on the hawkular-grafana-datasource querying usability, especially if you had the opportunity to create dashboards recently and had to juggle with querying by metric name and by tag.

Currently the panel displays different elements depending on you're querying by metric name (see picture: https://raw.githubusercontent.com/hawkular/hawkular-grafana-datasource/master/docs/images/search-by-name.png )

Querying by name is quite straightforward, but it can be cumbersome when there's a lot of available metrics and you have to scroll among suggestions to find the one you want.

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Or by tag  (see picture: https://raw.githubusercontent.com/hawkular/hawkular-grafana-datasource/master/docs/images/search-by-tag.png )

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The "query by tag" interface is not very intuitive IMO (you define a list of key-value pairs), moreover to this date there is no auto-completion on tag name.

There's been some features in metrics recently that, I think, can enable a better UI on Grafana side. First, there is Micke's feature "Allow fetching of available tagNames" [1] that enables suggestions (auto-completion) on tag name. And most importantly there's the new "tag query language" that could (should) have its place in Grafana.

So I would have several suggestions for improving the UI and queries.

1: First of all I think we can remove the "Search by name" / "Search by tag" selector, and allow searching by name AND by tag at the same time: providing tags would refine the available metrics in the metrics text field suggestions (auto-completion). If this text field is left blank, all available metrics are displayed.

Then, there's several scenarios to take advantage of the new hawkular metrics features:

2a: keep current key/value pairs system, but improve with adding suggestion on tag names.

2b: replace key-value pairs with the new tags query, via a simple text field:

We may or may not include syntax validation here. We must provide some documentation on that.

2c: replace key-value pairs with the new tags query, with a dedicated "builder" UI:

​Each of these boxes in tags query would have a contextual auto-completion feature:

- suggestions on 1: list of tag keys

- suggestions on 2: list of operators (=, !=, IN, NOT IN)

- suggestions on 3: list of tag values for the given key (with some slights differences on brackets if it's the first element or not; closing bracket as a choice if it's not the first element)

- suggestions on 4: operators AND / OR

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The 2b option is obviously simpler, very fast to implement. It has the downside of loosing all auto-completion capabilities, even compared to the current version.

2c looks nicer and more intuitive in its usage, people won't have to read the doc to use it. However there's several downsides:

  - Need to implement the logic => need for time for development, adds complexity to our grafana plugin.

  - Introduces a dependency to the language on server side. When the language evolves, we'll have to maintain this as well.

Ideas & thoughts? I think it's preferable to proceed in several steps. In a first time I could implement 1 and 2a, and later (and maybe giving some time to the language to be "stabilized") going with 2c.

[1] https://issues.jboss.org/browse/HWKMETRICS-532

Thanks