Correct Answer: C
In Prometheus, the part before the curly braces {} represents the metric name. Therefore, in the metric api_http_requests_total{method="POST", handler="/messages"}, the term api_http_requests_total is the metric name. Metric names describe the specific quantity being measured - in this example, the total number of HTTP requests received by an API.
The portion within the braces defines labels, which provide additional dimensions to the metric. Here, method="POST" and handler="/messages" are labels describing request attributes. The metric name should follow Prometheus conventions: lowercase letters, numbers, and underscores only, and ending in _total for counters.
This naming scheme ensures clarity and standardization across instrumented applications. The metric type (e.g., counter, gauge) is declared separately in the exposition format, not within the metric name itself.
Reference:
Verified from Prometheus documentation - Metric and Label Naming, Data Model, and Instrumentation Best Practices sections.
