Monitoring the ingestion pipeline with Grafana MCP

The ingestion pipeline (nodejs/) is PostHog's Node.js event processing layer. It consumes events from Kafka (produced by the capture service), runs them through processing steps (person resolution, group assignment, property overrides, etc.), and produces enriched events to ClickHouse-bound Kafka topics.

A single codebase is deployed as many K8s Deployments via the posthog-app Helm chart (golden-chart migration). Each deployment sets PLUGIN_SERVER_MODE and is distinguished in metrics by two default Prometheus labels:

• ingestion_pipeline — values: analytics, heatmaps, clientwarnings, errortracking
• ingestion_lane — values: main, overflow, historical, async, turbo

The app label (set by K8s pod labels) matches the deployment name and is the most universal scope filter across all telemetry domains.

This skill teaches how to discover live metrics using the Grafana MCP tools rather than memorizing metric names that change as the code evolves.