[Hawkular-dev] change to inventory metric model to store Prometheus info

[Lucas Ponce]

On Thu, Oct 26, 2017 at 11:48 PM, John Mazzitelli <mazz at redhat.com> wrote:

> I *think* I'm almost at the point where our inventory is able to store
> Prometheus metric data (metric family name and labels) in our inventory.
> Once done, you need only query inventory to get a resource's metric data
> and from there you will get the Prometheus metric family+labels so you know
> what you need to ask Prometheus for.
>
> Currently, there is no place in our Metric domain object in inventory for
> this information. Right now I am putting it in that generic properties:
>
>         // don't copy properties - we are using the inventory properties
> for P labels right now
>         //m.getProperties().forEach((k, v) -> mb.property(k,
> v.toString()));
>
>         // map to the Prometheus metric timeseries
>         mb.property("hawkular.metric.family", m.getMetricFamily());
>         mb.properties(m.getMetricLabels());
>
> The object "m" is the agent's own Metric object that has a generic
> properties map. Right now I don't think we store anything in there so that
> commented portion of the code is no big deal at the moment.
>
> But notice the metric family name and the metric labels are all in the
> same generic properties for the inventory Metric object (that's what mb is).
>
> I don't like this. It means who ever queries inventory has to strip out
> the "hawkular.metric.family" key from the metric generic properties - the
> rest of the map are the real labels.
>
> I think we should make these first-class attributes in the inventory model:
>
> mb.metricFamily(m.getMetricFamily())
> mb.metricLabels(m.getMetricLabels())
>
> Thoughts? (looking at you Joel :-)
>

I am not Joel, but jumping here, as we have thought on this too.

Do we want to split the Prometheus model ?

I mean, what if we consider a metricId also opaque, and we know that in P8S
is a combination of <metric_name><labels>, at the end of the day, is a
string and it is unique.

I ask this, because if we expose the details, it will be tempted to start
manipulating IDs in other layers, and perhaps that will create technical
debt.

So a metricId = "api_http_requests_total{method='POST',
handler='/messages'}" stored in the inventory will simplify tasks in other
layers as we can maintain the abstraction we are using today:

get_resource(resourceId).get_metric_id(metricId)

Or, I don't know if we can combine, maintaining an opaque metricId to
continue the model, and adding family and labels as properties/context in
those use cases are necessary.



>
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