Metrics with Micrometer in Spring Boot - Step-by-Step Execution

Concept Flow - Metrics with Micrometer

Start Application

↓

Micrometer Initialized

↓

Create MeterRegistry

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Define Metrics (Counters, Gauges, Timers)

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Application Runs

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Metrics Updated on Events

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Metrics Exported to Monitoring System

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End

Micrometer sets up a registry, defines metrics, updates them during app events, and exports data to monitoring tools.

Execution Sample

Spring Boot

Counter counter = registry.counter("requests_total");
counter.increment();
Timer.Sample sample = Timer.start(registry);
// code to time
sample.stop(registry.timer("request_latency"));

This code creates a counter and timer metric, increments the counter, and measures elapsed time for a code block.

Execution Table

Step	Action	Metric Type	Metric Name	Value Before	Value After	Description
1	Create counter	Counter	requests_total	0	0	Counter initialized at zero
2	Increment counter	Counter	requests_total	0	1	Counter increments by 1 on event
3	Start timer sample	Timer	request_latency	-	-	Timer sample started to measure duration
4	Stop timer sample	Timer	request_latency	0 ms	120 ms	Timer records 120 milliseconds duration
5	Export metrics	All	-	-	-	Metrics sent to monitoring system
6	End	-	-	-	-	Application continues running or stops

💡 Metrics are updated during app events and exported continuously or on demand.

Variable Tracker

Variable	Start	After Step 2	After Step 4	Final
requests_total (Counter)	0	1	1	1
request_latency (Timer)	-	-	120 ms	120 ms

Key Moments - 3 Insights

Why does the counter start at zero and not increment automatically?

Counters start at zero because they represent counts of events. They only increase when you explicitly call increment(), as shown in step 2 of the execution_table.

How does the timer measure the duration of code execution?

The timer starts when Timer.start() is called (step 3) and stops when sample.stop() is called (step 4), measuring the elapsed time between these calls.

When are metrics sent to the monitoring system?

Metrics are exported after updates or at configured intervals, as shown in step 5, ensuring monitoring tools receive current data.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of the counter 'requests_total' after step 2?

A 0

B 1

C 2

D Undefined

💡 Hint

Check the 'Value After' column for step 2 in the execution_table.

At which step does the timer record the duration of the code execution?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Look for when sample.stop() is called in the execution_table.

If the counter increment call is removed, what would be the value of 'requests_total' after step 2?

A 0

B 1

C Undefined

D Incremented by 2

💡 Hint

Refer to the variable_tracker and execution_table step 2 where increment happens.

Concept Snapshot

Micrometer Metrics Setup:
- Initialize MeterRegistry
- Define metrics: Counter, Gauge, Timer
- Increment counters on events
- Start/stop timers around code
- Export metrics to monitoring
- Metrics reflect app performance live

Full Transcript

Micrometer helps track app performance by creating metrics like counters and timers. You start by initializing a MeterRegistry, then define metrics such as counters for counting events and timers for measuring durations. When your app runs, you update these metrics by incrementing counters or timing code blocks. Finally, Micrometer exports these metrics to monitoring systems so you can see how your app behaves over time.