Generate RED metrics from trace spans using the OTel Collector spanmetrics connector

Steps

1. Add the spanmetrics connector to the OTel Collector config under the connectors section; configure it with histogram settings (explicit or exponential bucket boundaries) for latency, and set namespace to prefix generated metric names.
2. Wire the connector in the pipelines section: the traces pipeline must include spanmetrics in its exporters list, and a metrics pipeline must list spanmetrics in its receivers list; the connector sits at the junction between these two pipelines.
3. Configure dimensions in the spanmetrics connector to extract span attributes as metric labels (e.g., http.method, http.status_code, rpc.service); keep the cardinality of chosen dimensions low to avoid metric explosion.
4. Set metrics_flush_interval to control how often accumulated span metrics are flushed to the metrics pipeline; shorter intervals produce more up-to-date metrics but increase cardinality management overhead.
5. Forward the generated metrics (calls_total, duration, and optionally errors_total) to a Prometheus-compatible exporter or remote_write endpoint; configure the Prometheus exporter with a scrape endpoint or use prometheusremotewrite exporter.
6. Build Grafana or Datadog dashboards using the generated metrics to display request rate (calls_total rate), error rate (errors_total / calls_total), and latency percentiles (from the histogram) as the RED dashboard columns.