World map

 

BM

World O1: The Control Room

Metrics, logs and traces

You will learn: the three kinds of data a control room uses, and what each one is best at.

Checked with Prometheus 3 on 1 Nov 2026

The problem

The control room has three helpers: counters, a diary, a tracker. Who answers fastest: how many orders came in this minute?

Watch

bash
curl -s localhost:9100/metrics | grep 'node_load1 '
# HELP node_load1 1m load average.
# TYPE node_load1 gauge
node_load1 11.37

A metric: A number measured again and again over time, like orders per minute. is a name and a number. Prometheus writes down the time, again and again. Small, cheap, great for graphs.

Watch

Tap the line that explains a failed checkout.

0 of 1 found

A log: A diary line from the app: what happened, when, with details. is a diary line. It says what happened, when, with details.

Watch

Tap each point on the timeline.

A trace: One order followed through every service, with the time each step took. follows one order through every service. Each step is called a span. Tap each step.

Try it

Which helper holds this? Sort each one.

Drag a card into a box. Or tap the card, then tap the box.

        Predict

        At 12:30 the errors screen jumps. You want to know which error it is. What do you open next?

        You did it!

        You can now tell metrics, logs and traces apart.

        Go deeper (optional)

        They work best together. A metric rings the alarm. A log explains it. A trace points at the slow step. Prometheus keeps metrics. Logs and traces get their own world: O4.

        Prometheus writes its own diary too. This line is real:

        time=2026-11-01T12:50:04.542Z level=INFO source=main.go:1447 msg="Server is ready to receive web requests."

        Real rep (needs Docker, from Ship It D1):

        Real mission

        1. docker run -d --name prom-peek -p 9090:9090 quay.io/prometheus/prometheus:v3.13.5
        2. curl -s localhost:9090/metrics | head
        3. docker logs prom-peek
        4. docker rm -f prom-peek

        0 of 4 steps done · Your ticks are saved.