Metrics, Dashboards and SLIs/SLOs
Turn raw monitoring data into meaningful metrics and dashboards, and define Service Level Indicators and Objectives to measure reliability users actually care about.
Metrics, Dashboards and SLIs/SLOs is a free Docker & DevOps Fundamentals lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Docker & DevOps Fundamentals learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
From Data to Insight
Collecting metrics is only step one. To run reliable systems you need to turn numbers into dashboards and service-level targets that reflect real user experience.
The Four Golden Signals
Google SRE recommends watching four signals for any service: latency, traffic, errors, and saturation. They cover most user-facing problems.
Metric Types
Common metric shapes: a counter only goes up (requests served), a gauge rises and falls (memory in use), and a histogram buckets values (request durations).
Querying Metrics
Time-series databases like Prometheus use a query language to slice metrics. Here we compute the per-second request rate over five minutes.
rate(http_requests_total[5m])Building a Dashboard
Tools like Grafana turn queries into panels. A good dashboard answers a question at a glance - is the service healthy right now?
- Top row: golden signals
- Drill-down panels below
- Consistent time range
What Is an SLI?
A Service Level Indicator is a measured number reflecting user happiness - for example the fraction of requests served successfully and quickly.
sum(rate(http_requests_total{code!~"5.."}[5m]))
/
sum(rate(http_requests_total[5m]))What Is an SLO?
A Service Level Objective is a target for an SLI over a window - say, 99.9% of requests succeed over 30 days. It defines what good enough means.
SLA vs SLO
An SLA is a contractual promise to customers, often with penalties. SLOs are your internal, usually stricter, engineering targets.
Error Budgets
If your SLO is 99.9%, the remaining 0.1% is your error budget - the failure you can afford. Spend it on risky deploys; when it runs out, slow down and stabilize.
Alert on Symptoms, Not Causes
Page humans for what users feel (high error rate, slow responses), not every CPU blip. Symptom-based alerts reduce noise and fatigue.
Avoid Dashboard Sprawl
Too many dashboards is as bad as none. Keep a small set of trusted, owned dashboards tied to your SLOs rather than dozens of stale ones.
Quick Check
How do SLOs and error budgets relate?
Recap
You can now make monitoring meaningful:
- Watch the four golden signals
- Understand counters, gauges, histograms; query with rate()
- Define SLIs (measured) and SLOs (targets)
- Error budgets guide deploy pace; alert on symptoms
Reliability becomes something you measure and steer, not just hope for.
Frequently asked questions
Is the “Metrics, Dashboards and SLIs/SLOs” lesson free?
Yes — the full text of “Metrics, Dashboards and SLIs/SLOs” is free to read here on the web, and the Docker & DevOps Fundamentals course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Docker & DevOps Fundamentals course, upgrade to CoddyKit PRO.
What will I learn in “Metrics, Dashboards and SLIs/SLOs”?
Turn raw monitoring data into meaningful metrics and dashboards, and define Service Level Indicators and Objectives to measure reliability users actually care about. You practise Docker & DevOps Fundamentals with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Docker & DevOps Fundamentals?
No prior experience is required. Docker & DevOps Fundamentals on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Metrics, Dashboards and SLIs/SLOs” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Docker & DevOps Fundamentals lesson?
Yes. Every Docker & DevOps Fundamentals lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Introduction to Monitoring
- Centralized Logging Solutions
- Alerting and Incident Response
- Metrics, Dashboards and SLIs/SLOs