Monitor, log and load test

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Monitoring en loadtests — 7

Prometheus — metrics

Prometheus scrapes numbers from every target every 15–30 s; promtool checks its config and rules.

$promtool check config prometheus.yml
$promtool check rules alerts.yml
$curl -s 'http://prometheus:9090/api/v1/query?query=up' | jq '.data.result[] | [.metric.instance, .value[1]]'

10.2

node_exporter — server metrics

node_exporter gives CPU, memory, disk and network numbers of a Linux server on port 9100.

$curl -s localhost:9100/metrics | grep node_filesystem_avail_bytes

10.3

Grafana — dashboards

Grafana shows metrics, logs and traces in dashboards; grafana-cli installs plugins and resets the admin password.

#grafana-cli plugins install grafana-piechart-panel
#systemctl restart grafana-server

10.4

Loki — logs

Loki stores logs with labels; logcli queries them from the terminal.

$logcli query '{namespace="shop", app="shop"} |= "ERROR"' --since 1h
$logcli query 'sum by (status) (count_over_time({app="nginx"} | json [5m]))'

10.5

OpenTelemetry Collector — one pipe for all signals

otelcol receives traces, metrics and logs (OTLP), processes them and sends them to any backend.

$otelcol --config /etc/otelcol/config.yaml validate
$otelcol --config /etc/otelcol/config.yaml

10.6

k6 and ab — load tests

k6 runs scripted load tests with pass/fail thresholds; ab is a quick one-URL benchmark.

$k6 run -e BASE_URL=https://staging.example.com load.js
$ab -k -n 2000 -c 50 https://staging.example.com/

10.7

Alert on symptoms, not on causes

Good alerts tell you users have a problem; the dashboards then show why.

Watch the 4 golden signals: latency, traffic, errors, saturation.
Alert on an error rate or slow p95 latency over 5–10 minutes — not on one CPU spike.
Every alert has a runbook link: what to check, how to fix.
Define SLOs ("99.9 % of requests OK per month") and alert on the error budget.

Onthoud

An alert nobody acts on is noise. Delete it or fix it.

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