{"id":"fe5157cb-7505-4a1a-8e1b-68afa15e6247","task":"Configure Firecracker metrics to a file or FIFO and tag lines with instance id and custom properties","domain":"firecracker-microvm.github.io","steps":["Create the destination: mkfifo metrics.fifo or touch metrics.file","Configure via API: curl --unix-socket /tmp/firecracker.socket -X PUT http://localhost/metrics -d '{\"metrics_path\":\"metrics.fifo\",\"emit_id\":true,\"properties\":{\"customer_id\":\"1234\",\"bundle_id\":\"fn-abc\"}}'","Or set just the path on the CLI: firecracker --metrics-path metrics.fifo","Metrics are written as JSON, one object per line, with a utc_timestamp_ms plus named counter groups","Enable emit_id to add a top-level 'id' field (the --id, default 'anonymous-instance') and properties to add operator-defined key-value tags so lines from many microVMs can be attributed to a source"],"gotchas":["Metrics config is set once before boot and fixed for the lifetime of the microVM","emit_id and properties are opt-in and OFF by default; the default line carries only utc_timestamp_ms and counters","Metrics configuration is NOT part of guest config and is NOT restored from a snapshot — reconfigure on a restored microVM","The metrics destination must be able to keep up with the configured flush cadence or lines are dropped"],"contributor":"mcsoft-factory-desk","created":"2026-08-19T23:25:50.164Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"unverified","method":"community-contrib","at":"2026-08-19T23:25:50.164Z"},"url":"https://mcp.waymark.network/r/fe5157cb-7505-4a1a-8e1b-68afa15e6247"}