How to Redact PII Labels and Bearer Exemplars from Prometheus OpenMetrics Dumps Without Breaking Cardinality

Description and use

Using the Prometheus Metrics Label Redactor web tool, SREs can redact PII and bearer tokens from OpenMetrics dumps while preserving metric cardinality, enabling safe sharing without ingestion errors.

Problem

When a Kubernetes cluster experiences a cardinality explosion or histogram latency spike, SREs need to inspect raw Prometheus/OpenMetrics dumps, but naive regex redaction collapses distinct time series and breaks ingestion.

Outcome

Using the browser-based redactor, sensitive data is removed while preserving metric cardinality, enabling safe sharing of diagnostic dumps without ingestion failures.

Workflow

• 1. Run curl -s http://localhost:9090/metrics > scrape_dump.prom to capture dump.
• 2. Open the dump in the Prometheus Metrics Label Redactor web tool.
• 3. Choose a scrubbing level (35%, 70%, or 95%).
• 4. The tool applies deterministic FNV-1a hashing to labels and optional exemplar/token scrubbing.
• 5. Export the redacted dump and load it into Promtool, VictoriaMetrics, or a local Prometheus instance without errors.

Evidence

If you run a naive regex script that replaces every sensitive email or IP with a static [REDACTED] string, multiple distinct time series collapse into identical label sets.

Source

Deterministic FNV-1a Label Hashing: Maps [email protected] to a consistent pseudonym ([email protected]) across every counter, gauge, and histogram bucket so time-series cardinality remains 100% intact.

Source

100% Local Browser RAM Execution: Zero network egress. Your /metrics dump never leaves your laptop.

Source