Missing boundaries option in HistogramOptions

[fallenmanrisesup]

latest otel package versions, node 12

const { metrics, ValueType } = require("@opentelemetry/api-metrics");
// ...
const meter = metrics.getMeter(packageJSON.name, packageJSON.version);
const h1 = meter.createHistogram('test-metric', {
  boundaries: [0, 10, 100],
});
const h2 = meter.createHistogram('test-metric-2', {
  boundaries: [0, 5, 7, 9, 11, 13],
});

I tried to set up custom boundaries for buckets (I need exclusive for each instance, not for agregator), there is no boundaries option
in HistogramOptions .

[legendecas]

This is by design. The boundaries now should be configured with Views. You can do it like

const { ExplicitBucketHistogramAggregation, InstrumentType } = require('@opentelemetry/sdk-metrics-sdk');
meterProvider.addView({
  aggregation: new ExplicitBucketHistogramAggregation([ /* custom boundaries */]);
}, {
  instrument: {
    type: InstrumentType.HISTOGRAM,
  },
});

// After the view is added, create the metric instrument
const h1 = meter.createHistogram('test-metric');

[fallenmanrisesup]

@legendecas It will give those boundaries for each histogram created by meter. I need to create N histogram metrics with it's own boundaries per metric

[vmarchaud]

When adding a view you can target a specific instrument name/type/description https://github.com/open-telemetry/opentelemetry-js/blob/main/experimental/packages/opentelemetry-sdk-metrics-base/test/MeterProvider.test.ts#L177

[legendecas]

Closing as the question has been answered. Please feel to reopen if that is not the case.

[nwalters512]

I moved the below discussion to #3619.

Let me know if I should open a new issue for discussion, but this is really unergonomic in real-world code. While I recognize that it's neat to be able to take a single histogram and get multiple metrics out of it via Views, I'd consider the bucket boundaries to be an integral part of the histogram itself in most situations, and it would make a lot of sense to define the boundaries where the histogram itself is defined. Instead, I'd have to define these views where I initialize OTel, which is going to be in a completely unrelated part of my code. And AFAICT, there's no way to add or update views once a MeterProvider is instantiated.

This also means that there's no straightforward way share and reuse histogram metrics via libraries, as one can't ship the histogram buckets alongside the metric itself. This would be really useful for e.g. building a library that can capture common Node metrics, including a histogram for GC duration. I'm thinking about something akin to this from the Prometheus world: https://github.com/siimon/prom-client/blob/8d6456c05f0708fed34628da5bd6f492a0ab43f8/lib/metrics/gc.js.

Is there anything on the horizon that would make this easier?