How to build Metrics using OpenTelemetry SDK?

[swapnil-kotwal-sp]

Hey Team,

I've just started my journey with OpenTelemetry. My basic Objective is to get the Metrics for no. of successful & failed operations.
I've written below code sniped, I could see my data is getting ingested to Prometheus but

Que 1: does below piece of code is correct as per my expectations?
Que 2: I'm not getting any details about span attributes or tags etc... What I'm missing here? When I decompiled this code.. There I could see span section as Exception exception = null
Que 3: I'm adding successful counter.add(1); same way I will have to instantiate -ve counter object for unsuccessful operations?

		OpenTelemetry openTelemetry = ExampleConfiguration.initOpenTelemetry();
		Tracer tracer = openTelemetry.getTracer("test instrumentation", "1.0.0");
		// Gets or creates a named meter instance
		Meter meter = openTelemetry.meterBuilder("test instrumentation")
				.setInstrumentationVersion("1.0.0").build();
		// Build counter e.g. LongCounter
		LongCounter counter = meter
				.counterBuilder("test_counter")
				.setDescription("test_counter jobs")
				.setUnit("1")
				.build();
		LongHistogram histogram = meter.histogramBuilder("super_timer").ofLongs().setUnit("ms").build();

		for (int i = 0; i < 100; i++) {
			long startTime = System.currentTimeMillis();
			Span span = tracer.spanBuilder("exampleSpan").startSpan();

			try (Scope scope = span.makeCurrent()) {
				span.setAttribute("good", "true");
				span.setAttribute("exampleNumber", i);
				counter.add(1);
				span.setStatus(StatusCode.OK, "Something good happened!");
				Thread.sleep(100);
			} catch (Throwable throwable) {
				//counter.add(1); shall I add -ve counter here?
				span.setStatus(StatusCode.ERROR, "Something bad happened!");
				span.recordException(throwable);
				throw throwable;
			} finally {
				histogram.record(System.currentTimeMillis() - startTime);
				span.end();
			}
		}

[jkwatson]

Que 2: I'm not getting any details about span attributes or tags etc... What I'm missing here? When I decompiled this code.. There I could see span section as Exception exception = null

It doesn't look like you're recording any of those in your metrics, so I wouldn't expect them to be there. The SDK does not automatically apply span attributes to metrics.

[jkwatson]

the histogram aggregations usually include the count of the total recordings, so I don't that the counter here adds much more than you would get from the histograms. If you include an attribute that flags failure or not, you should be able to distinguish the counts from the two different attribute values, I would think.

[swapnil-kotwal-sp]

Got it, I was mixing up TracerProvider, Span & Histogram where I suppose to only instantiate 2 counter instances and have to send it to Otl-collector

e.g.

LongCounter counter1 = meter
				.counterBuilder("test_counter")
				.setDescription("test_counter jobs")
				.setUnit("1")
				.build();

LongCounter counter2 = meter
				.counterBuilder("test_counter")
				.setDescription("test_counter jobs")
				.setUnit("1")
				.build();

counter1.add(1, attributesSuccess);
counter2.add(1, attributesFailures);