A resource tag is a named metadata field attached to a metric value. In Prometheus, labels distinguish otherwise similar measurements, such as the hostname of each container producing access-log metrics. section 9.3
Use resource tags to inspect and compare distributed workloads:
- Scale the access-log service to three containers and send requests to the application. section 9.3
- Open the Prometheus UI and query access_log_total to see one metric value per container. section 9.3
- Compare the tagged values to evaluate how evenly requests are load-balanced. section 9.3
Aggregate across resources
When individual container tags are not needed, sum the metric while excluding hostname and instance: sum(access_log_total) without(hostname, instance). The result combines values across containers and can be graphed over time. section 9.3
sum(access_log_total) without(hostname, instance)
Inspect the PromQL aggregation that removes per-resource distinctions and produces a combined metric. section 9.3
