8.1 Tasks: Relabeling

Relabeling in Prometheus can be used to perform numerous tasks using regular expressions, such as

• adding, modifying or removing labels to/from metrics or alerts,
• filtering metrics based on labels, or
• enabling horizontal scaling of Prometheus by using hashmod relabeling.

It is a very powerful part of the Prometheus configuration, but it can also get quite complex and confusing. Thus, we will only take a look at some basic/simple examples.

There are four types of relabelings:

• relabel_configs (target relabeling)

  Target relabeling is defined in the job definition of a scrape_config. When using the Prometheus Operator, custom relabel_configs can be added to the ServiceMonitor. This concept is also used to configure scraping of a multi-target exporter (e.g., blackbox_exporter or snmp_exporter) where one single exporter instance is used to scrape multiple targets. Check out the Prometheus docs for a detailed explanation and example configurations of relabel_configs.

• metric_relabel_configs (metrics relabeling)

  Metrics relabeling is applied to scraped samples right before ingestion. It allows adding, modifying, or dropping labels or even dropping entire samples if they match certain criteria.

• alert_relabel_configs (alert relabeling)

  Alert relabeling is similar to metric_relabel_configs, but applies to outgoing alerts.

• write_relabel_configs (remote write relabeling)

  Remote write relabeling is similar to metric_relabel_configs, but applies to remote_write configurations.