Guides

How to Set Up Prometheus and Grafana for Beginners

By Ravindra Bagale, DevOps trainer · LinkedIn · Published: 28 October 2026 · Last updated: 28 October 2026

Configure Prometheus scrapes until Targets are UP, add Prometheus as a Grafana data source, build a PromQL panel, and save the dashboard.

Language: English · मराठी · हिंदी

Why Prometheus + Grafana

Metrics need storage and eyes.

Why: SSH top does not scale to many services. What: Prometheus scrapes; Grafana graphs. How: Start with self-scrape then exporters.

Example 1: Prometheus config scrape sketch

Type this:

mkdir -p /tmp/prom && printf '%s\n' 'global:' '  scrape_interval: 15s' 'scrape_configs:' '  - job_name: "prometheus"' '    static_configs:' '      - targets: ["localhost:9090"]' > /tmp/prom/prometheus.yml && cat /tmp/prom/prometheus.yml

You will see:

global:

What it means: Prometheus scrapes targets on an interval — self-scrape first.

Example 2: Run Prometheus (compose-style idea)

Type this:

printf '%s\n' 'docker run --rm -p 9090:9090 -v /tmp/prom/prometheus.yml:/etc/prometheus/prometheus.yml public.ecr.aws/bitnami/prometheus:latest'

You will see:

docker run --rm -p 9090:9090 -v /tmp/prom/prometheus.yml:/etc/prometheus/prometheus.yml public.ecr.aws/bitnami/prometheus:latest

What it means: Lab path; production uses HA and persistent storage.

Example 7: Targets page check

Type this:

printf '%s\n' 'Open Prometheus UI → Status → Targets — State should be UP'

You will see:

Open Prometheus UI → Status → Targets — State should be UP

What it means: DOWN means scrape failed (network, path, or auth).

Concept 1: Scrape and query

Jobs, targets, PromQL.

Why: DOWN targets make empty graphs. What: Targets UP; up{}; rate(). How: Add node exporter job.

Example 3: Query up metric

Type this:

printf '%s\n' 'up{job="prometheus"}'

You will see:

up{job="prometheus"}

What it means: up==1 means the target answered the scrape.

Example 5: First panel PromQL

Type this:

printf '%s\n' 'rate(process_cpu_seconds_total[1m])'

You will see:

rate(process_cpu_seconds_total[1m])

What it means: rate() turns counters into a per-second view for graphs.

Example 8: Add a node exporter job

Type this:

printf '%s\n' '  - job_name: "node"' '    static_configs:' '      - targets: ["node-exporter:9100"]' >> /tmp/prom/prometheus.yml && tail -4 /tmp/prom/prometheus.yml

You will see:

- job_name: "node"

What it means: Exporters expose metrics Prometheus understands.

Concept 2: Grafana panels

Datasource then Explore then save.

Why: Unsaved work vanishes. What: Prometheus type URL; Explore; Save. How: Name dashboards clearly.

Example 4: Grafana datasource JSON sketch

Type this:

printf '%s\n' '{' '  "name": "Prometheus",' '  "type": "prometheus",' '  "url": "http://prometheus:9090",' '  "access": "proxy"' '}' > /tmp/prom/ds.json && cat /tmp/prom/ds.json

You will see:

{

What it means: Grafana reads Prometheus over HTTP as a data source.

Example 6: Save dashboard reminder

Type this:

printf '%s\n' 'Save the dashboard with a clear name: App CPU — Payments'

You will see:

Save the dashboard with a clear name: App CPU — Payments

What it means: Unsaved panels vanish on refresh — Infosys demos warn about this.

Example 10: Grafana Explore

Type this:

printf '%s\n' 'Grafana → Explore → pick Prometheus → run PromQL → see graph'

You will see:

Grafana → Explore → pick Prometheus → run PromQL → see graph

What it means: Explore before you build a full dashboard.

Concept 3: Ops basics

Reload, retention, pull model.

Why: Restarting blindly loses learners time. What: lifecycle reload; know retention limits. How: Pull vs push interview line.

Example 9: Reload config

Type this:

printf '%s\n' 'curl -X POST http://127.0.0.1:9090/-/reload'

You will see:

curl -X POST http://127.0.0.1:9090/-/reload

What it means: Requires --web.enable-lifecycle; else restart the process.

Example 11: Retention note

Type this:

printf '%s\n' 'Local Prometheus keeps short retention; long-term needs Thanos/Mimir later'

You will see:

Local Prometheus keeps short retention; long-term needs Thanos/Mimir later

What it means: Beginners start local; companies add long-term storage.

Example 12: Interview line

Type this:

printf '%s\n' 'Prometheus pulls (scrapes); many older tools push — that is the mental model'

You will see:

Prometheus pulls (scrapes); many older tools push — that is the mental model

What it means: TCS interviews open with pull vs push.

Prom/Grafana card

1 prometheus.yml scrape 2 Targets UP 3 Grafana Prometheus datasource 4 PromQL panel 5 Save dashboard

Suppose: Target DOWN

Check network, path /metrics, and job config.

Suppose: empty graph

Use rate() on counters; confirm time range.

Check yourself (quiz)

scrape → UP → datasource → panel → save. Did you understand? Let us try it once more.