Prometheus and Grafana integration concept in Spring Boot - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Prometheus used for in monitoring?

Prometheus collects and stores metrics data from applications and systems to help monitor their performance and health.

beginner

What role does Grafana play when integrated with Prometheus?

Grafana visualizes the metrics data collected by Prometheus, creating easy-to-understand dashboards and graphs.

intermediate

How does a Spring Boot application expose metrics for Prometheus?

Spring Boot exposes metrics through an HTTP endpoint (usually /actuator/prometheus) that Prometheus scrapes to collect data.

intermediate

What is the purpose of the Prometheus scrape configuration?

It tells Prometheus where to find the metrics endpoints of applications, so it knows which URLs to collect data from and how often.

beginner

Why is it helpful to use both Prometheus and Grafana together?

Prometheus gathers raw metrics data, and Grafana turns that data into visual dashboards, making it easier to understand system health and spot issues.

Which endpoint does a Spring Boot app usually expose for Prometheus metrics?

A /actuator/prometheus

B /metrics/data

C /api/metrics

D /monitoring/stats

Spring Boot uses the /actuator/prometheus endpoint to expose metrics in a format Prometheus can scrape.

What does Prometheus do with the metrics it collects?

A Visualizes data in dashboards

B Sends alerts directly to users

C Stores them in a time-series database

D Deletes old logs

Prometheus stores metrics in a time-series database for later querying and analysis.

Grafana connects to Prometheus to:

A Send metrics to applications

B Visualize metrics data

C Collect metrics data

D Configure Prometheus scraping

Grafana is a visualization tool that creates dashboards from data stored in Prometheus.

In Prometheus configuration, what is a 'scrape job'?

A A data backup process

B A user alert notification

C A dashboard template

D A task to collect metrics from a target URL

A scrape job defines how and where Prometheus collects metrics data.

Why is it important to expose metrics in a standard format for Prometheus?

A So Prometheus can understand and collect the data correctly

B To improve application speed

C To secure the application

D To reduce memory usage

Prometheus expects metrics in a specific format to scrape and store them properly.

Explain how Prometheus and Grafana work together to monitor a Spring Boot application.

Think about data flow from app to visualization.

Describe the steps to configure Prometheus to monitor a Spring Boot app.

Focus on setup from app to Prometheus and then Grafana.

Practice

1. What is the primary role of Prometheus in a Spring Boot application monitoring setup?

easy

A. To collect metrics by scraping the application's exposed endpoint

B. To visualize metrics using dashboards

C. To expose application metrics automatically

D. To send alerts directly to users

Solution

1. Step 1: Understand Prometheus function

   Prometheus collects metrics by scraping HTTP endpoints exposed by applications.

2. Step 2: Differentiate roles of tools

   Grafana is used for visualization, not collection. Spring Boot exposes metrics but does not collect them.

3. Final Answer:

   To collect metrics by scraping the application's exposed endpoint -> Option A

4. Quick Check:

   Prometheus collects metrics = A [OK]

Hint: Remember: Prometheus scrapes, Grafana shows [OK]

Common Mistakes:

• Confusing Grafana as the collector
• Thinking Spring Boot collects metrics
• Assuming Prometheus sends alerts directly

2. Which dependency must be added to a Spring Boot project to expose metrics for Prometheus scraping?

easy

A. spring-boot-starter-web

B. spring-boot-starter-data-jpa

C. micrometer-registry-prometheus

D. spring-boot-starter-security

Solution

1. Step 1: Identify metrics registry dependency

   Micrometer provides metrics support; the Prometheus registry enables exposing metrics in Prometheus format.

2. Step 2: Exclude unrelated dependencies

   Web starter is for REST APIs, JPA for database, Security for auth; none expose Prometheus metrics.

3. Final Answer:

   micrometer-registry-prometheus -> Option C

4. Quick Check:

   Prometheus metrics need micrometer-registry-prometheus [OK]

Hint: Add micrometer-registry-prometheus for Prometheus metrics [OK]

Common Mistakes:

• Adding only spring-boot-starter-web without metrics registry
• Confusing JPA or Security starters as metrics providers
• Forgetting to include Prometheus registry dependency

3. Given this Spring Boot application.properties snippet:
management.endpoints.web.exposure.include=health,prometheus
management.endpoint.prometheus.enabled=true
What will be the URL path to scrape metrics for Prometheus?

medium

A. /metrics

B. /actuator/metrics

C. /prometheus/metrics

D. /actuator/prometheus

Solution

1. Step 1: Understand actuator endpoint exposure

   Spring Boot exposes actuator endpoints under /actuator by default.

2. Step 2: Identify Prometheus endpoint path

   Prometheus metrics endpoint is /actuator/prometheus when enabled and exposed.

3. Final Answer:

   /actuator/prometheus -> Option D

4. Quick Check:

   Prometheus metrics at /actuator/prometheus [OK]

Hint: Actuator endpoints default under /actuator [OK]

Common Mistakes:

• Using /metrics instead of /actuator/prometheus
• Assuming /prometheus/metrics is default
• Forgetting to enable prometheus endpoint

4. You configured Prometheus to scrape your Spring Boot app, but metrics are not appearing in Grafana. Which is the most likely cause?

medium

A. Prometheus server is down but Grafana is running

B. Prometheus is not scraping the correct endpoint URL

C. Spring Boot app does not have a database connection

D. Grafana does not support Prometheus data sources

Solution

1. Step 1: Check Prometheus scraping configuration

   If Prometheus scrapes wrong URL, no metrics collected, so Grafana shows nothing.

2. Step 2: Exclude other causes

   Grafana supports Prometheus; database unrelated; if Prometheus down, Grafana shows errors.

3. Final Answer:

   Prometheus is not scraping the correct endpoint URL -> Option B

4. Quick Check:

   Wrong scrape URL blocks metrics flow [OK]

Hint: Verify Prometheus scrape URL matches app endpoint [OK]

Common Mistakes:

• Blaming Grafana for lack of support
• Assuming database affects metrics exposure
• Ignoring Prometheus scrape configuration

5. You want to create a Grafana dashboard showing the average response time of your Spring Boot app over the last 5 minutes. Which Prometheus query should you use?

hard

A. rate(http_server_requests_seconds_sum[5m]) / rate(http_server_requests_seconds_count[5m])

B. sum(http_server_requests_seconds_sum) / sum(http_server_requests_seconds_count)

C. avg_over_time(http_server_requests_seconds_sum[5m])

D. count_over_time(http_server_requests_seconds_count[5m])

Solution

1. Step 1: Understand metrics for response time

   http_server_requests_seconds_sum is total time; count is number of requests.

2. Step 2: Calculate average over 5 minutes

   Use rate() to get per-second increase, then divide sum by count for average.

3. Final Answer:

   rate(http_server_requests_seconds_sum[5m]) / rate(http_server_requests_seconds_count[5m]) -> Option A

4. Quick Check:

   Average = sum rate / count rate [OK]

Hint: Divide sum rate by count rate for average response time [OK]

Common Mistakes:

• Using sum without rate causes wrong aggregation
• Using avg_over_time on sum metric alone
• Counting requests instead of averaging time