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Prometheus

https://prometheus.io/

Monitoring system & time series database

Introduction​

Supports monitoring anything

  • App
  • Server
  • Database

Metrics Collection​

Pulls over HTTP​

Target needs to expose /metrics endpoint.

Prometheus calls the endpoint to retrieve metric.

Exporter​

There are things that doesn't natively support the /metrics endpoint.

Exporter is an adapter that converts metrics to the format prometheus understands and expose metrics.

Exporters are also availble as docker image. For example, to export metrics of a MySQL DB, one can use a side car docker container exporter.

Config​

A yml file is used to specify the targets.

Data Storage​

Supports both local and Remote Storage.

Query​

  • Use language PromQL on Prometheus Web UI and get metric data.
  • Use data visualization tools like Grafana

Example PromQL

# All HTTP status codes except 4xx ones
http_requests_total{status!~"4.."}

# 5-min rate of `http_requests_total` for the past 30 mins
rate(http_requests_total[5m])[30m:]

Alert​

Alerts are defined by rules. Alertmanager is responsible for pushing alerts, email, slack, etc.

Reference​