Connection

Access Prometheus Web UI http://localhost:9090 curl API endpoint curl http://localhost:9090/api/v1/query?query=up Configure Prometheus Edit prometheus.yml file Start Prometheus prometheus --config.file=prometheus.yml

Querying

Basic query http_requests_total Filter by label http_requests_total{status="200"} Range query http_requests_total[5m] Rate rate(http_requests_total[5m]) Sum by sum by(instance) (http_requests_total) Increase increase(http_requests_total[1h]) Aggregation functions sum(), avg(), min(), max(), count()

Alert Management

View alerts http://localhost:9090/alerts List alertmanager targets http://localhost:9090/targets Define alert rule In prometheus.yml or rules file

Management

List targets http://localhost:9090/targets View configuration http://localhost:9090/config View service discovery http://localhost:9090/service-discovery Runtime information http://localhost:9090/status

PromQL (Advanced)

Quantile histogram_quantile(0.95, rate(http_request_duration_seconds_bucket[5m])) Predict linear trend predict_linear(node_filesystem_free_bytes[1h], 4 * 3600) Counter reset handling resets(http_requests_total[5m]) Conversion to per-second irate(http_requests_total[5m]) Delta for gauges delta(temperature_celsius[1h])

CLI Options

Specify config file --config.file=prometheus.yml Set storage path --storage.tsdb.path=data/ Retention time --storage.tsdb.retention.time=15d HTTP listen address --web.listen-address=0.0.0.0:9090 External URL --web.external-url=http://prometheus.example.org