├── src
├── main
│ ├── resources
│ │ ├── application.properties
│ │ └── static
│ │ │ └── index.html
│ └── java
│ │ └── com
│ │ └── tutorialworks
│ │ └── demos
│ │ └── springbootwithmetrics
│ │ ├── Greeting.java
│ │ ├── SpringBootWithMetricsApplication.java
│ │ └── GreetingController.java
└── test
│ └── java
│ └── com
│ └── tutorialworks
│ └── demos
│ └── springbootwithmetrics
│ └── SpringBootWithMetricsApplicationTests.java
├── renovate.json
├── .gitignore
├── prometheus.yml
├── pom.xml
├── README.md
└── LICENSE
/src/main/resources/application.properties:
--------------------------------------------------------------------------------
1 | management.endpoints.web.exposure.include=health,info,prometheus
2 |
--------------------------------------------------------------------------------
/renovate.json:
--------------------------------------------------------------------------------
1 | {
2 | "$schema": "https://docs.renovatebot.com/renovate-schema.json",
3 | "extends": [
4 | "config:base"
5 | ]
6 | }
7 |
--------------------------------------------------------------------------------
/src/main/resources/static/index.html:
--------------------------------------------------------------------------------
1 |
2 |
3 | Spring Boot Micrometer example
4 |
5 |
6 |
7 | Get a greeting
8 |
9 | View Prometheus metrics endpoint
10 |
11 |
--------------------------------------------------------------------------------
/src/main/java/com/tutorialworks/demos/springbootwithmetrics/Greeting.java:
--------------------------------------------------------------------------------
1 | package com.tutorialworks.demos.springbootwithmetrics;
2 |
3 | public class Greeting {
4 |
5 | private final long id;
6 | private final String content;
7 |
8 | public Greeting(long id, String content) {
9 | this.id = id;
10 | this.content = content;
11 | }
12 |
13 | public long getId() {
14 | return id;
15 | }
16 |
17 | public String getContent() {
18 | return content;
19 | }
20 | }
21 |
--------------------------------------------------------------------------------
/.gitignore:
--------------------------------------------------------------------------------
1 | HELP.md
2 | target/
3 | !.mvn/wrapper/maven-wrapper.jar
4 | !**/src/main/**/target/
5 | !**/src/test/**/target/
6 |
7 | ### STS ###
8 | .apt_generated
9 | .classpath
10 | .factorypath
11 | .project
12 | .settings
13 | .springBeans
14 | .sts4-cache
15 |
16 | ### IntelliJ IDEA ###
17 | .idea
18 | *.iws
19 | *.iml
20 | *.ipr
21 |
22 | ### NetBeans ###
23 | /nbproject/private/
24 | /nbbuild/
25 | /dist/
26 | /nbdist/
27 | /.nb-gradle/
28 | build/
29 | !**/src/main/**/build/
30 | !**/src/test/**/build/
31 |
32 | ### VS Code ###
33 | .vscode/
34 |
--------------------------------------------------------------------------------
/prometheus.yml:
--------------------------------------------------------------------------------
1 | # Sample Prometheus config
2 | # This assumes that your Prometheus instance can access this application on localhost:8080
3 |
4 | global:
5 | scrape_interval: 15s # Set the scrape interval to every 15 seconds. Default is every 1 minute.
6 | evaluation_interval: 15s # Evaluate rules every 15 seconds. The default is every 1 minute.
7 | # scrape_timeout is set to the global default (10s).
8 |
9 | scrape_configs:
10 | - job_name: 'spring boot scrape'
11 | metrics_path: '/actuator/prometheus'
12 | scrape_interval: 5s
13 | static_configs:
14 | - targets: ['localhost:8080']
15 |
--------------------------------------------------------------------------------
/src/main/java/com/tutorialworks/demos/springbootwithmetrics/SpringBootWithMetricsApplication.java:
--------------------------------------------------------------------------------
1 | package com.tutorialworks.demos.springbootwithmetrics;
2 |
3 | import io.micrometer.core.aop.TimedAspect;
4 | import io.micrometer.core.instrument.MeterRegistry;
5 | import org.springframework.boot.SpringApplication;
6 | import org.springframework.boot.autoconfigure.SpringBootApplication;
7 | import org.springframework.context.annotation.Bean;
8 |
9 | @SpringBootApplication
10 | public class SpringBootWithMetricsApplication {
11 |
12 | public static void main(String[] args) {
13 | SpringApplication.run(SpringBootWithMetricsApplication.class, args);
14 | }
15 |
16 | /**
17 | * This is required so that we can use the @Timed annotation
18 | * on methods that we want to time.
19 | * See: https://micrometer.io/docs/concepts#_the_timed_annotation
20 | */
21 | @Bean
22 | public TimedAspect timedAspect(MeterRegistry registry) {
23 | return new TimedAspect(registry);
24 | }
25 |
26 | }
27 |
--------------------------------------------------------------------------------
/src/test/java/com/tutorialworks/demos/springbootwithmetrics/SpringBootWithMetricsApplicationTests.java:
--------------------------------------------------------------------------------
1 | package com.tutorialworks.demos.springbootwithmetrics;
2 |
3 | import io.micrometer.core.instrument.MeterRegistry;
4 | import org.junit.jupiter.api.Test;
5 | import org.springframework.beans.factory.annotation.Autowired;
6 | import org.springframework.boot.test.context.SpringBootTest;
7 | import org.springframework.boot.test.web.client.TestRestTemplate;
8 | import org.springframework.http.ResponseEntity;
9 |
10 | import java.util.Map;
11 |
12 | import static org.assertj.core.api.Assertions.assertThat;
13 |
14 | /**
15 | * Basic integration tests to check that metrics are rendered.
16 | */
17 | @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
18 | class SpringBootWithMetricsApplicationTests {
19 |
20 | @Autowired
21 | private TestRestTemplate restTemplate;
22 |
23 | @Autowired
24 | MeterRegistry registry;
25 |
26 | /**
27 | * Sends a test request to the Greeting API, then asserts that the counter
28 | * has increased to 1.
29 | * @throws InterruptedException
30 | */
31 | @Test
32 | void testMetricsRequestCounterIncreases() throws InterruptedException {
33 | // Make a test request to the Greeting service
34 | ResponseEntity response = this.restTemplate.getForEntity("/greeting", String.class);
35 |
36 | assertThat(registry.get("greetings.counter").counter().count()).isEqualTo(1);
37 | }
38 |
39 | }
40 |
--------------------------------------------------------------------------------
/src/main/java/com/tutorialworks/demos/springbootwithmetrics/GreetingController.java:
--------------------------------------------------------------------------------
1 | package com.tutorialworks.demos.springbootwithmetrics;
2 |
3 | import io.micrometer.core.annotation.Timed;
4 | import io.micrometer.core.instrument.MeterRegistry;
5 | import org.springframework.web.bind.annotation.GetMapping;
6 | import org.springframework.web.bind.annotation.RequestParam;
7 | import org.springframework.web.bind.annotation.RestController;
8 |
9 | import java.util.concurrent.atomic.AtomicLong;
10 |
11 | @RestController
12 | public class GreetingController {
13 |
14 | private static final String template = "Hello, %s!";
15 | private final AtomicLong counter = new AtomicLong();
16 |
17 | private final MeterRegistry registry;
18 |
19 | /**
20 | * We inject the MeterRegistry into this class
21 | */
22 | public GreetingController(MeterRegistry registry) {
23 | this.registry = registry;
24 | }
25 |
26 | /**
27 | * The @Timed annotation adds timing support, so we can see how long
28 | * it takes to execute in Prometheus
29 | * percentiles
30 | */
31 | @GetMapping("/greeting")
32 | @Timed(value = "greeting.time", description = "Time taken to return greeting",
33 | percentiles = {0.5, 0.90})
34 | public Greeting greeting(@RequestParam(value = "name", defaultValue = "World") String name) {
35 | registry.counter("greetings.counter").increment();
36 | return new Greeting(counter.incrementAndGet(), String.format(template, name));
37 | }
38 |
39 | }
40 |
--------------------------------------------------------------------------------
/pom.xml:
--------------------------------------------------------------------------------
1 |
2 |
4 | 4.0.0
5 |
6 | org.springframework.boot
7 | spring-boot-starter-parent
8 | 3.1.5
9 |
10 |
11 | com.tutorialworks.demos
12 | spring-boot-with-metrics
13 | 1.0.0-SNAPSHOT
14 | spring-boot-with-metrics
15 | Spring Boot with Metrics Demo
16 |
17 |
18 | 17
19 |
20 |
21 |
22 |
23 | org.springframework.boot
24 | spring-boot-starter-web
25 |
26 |
27 | org.springframework.boot
28 | spring-boot-starter-actuator
29 |
30 |
31 |
32 |
33 | org.springframework.boot
34 | spring-boot-starter-aop
35 |
36 |
37 |
38 | io.micrometer
39 | micrometer-registry-prometheus
40 | runtime
41 |
42 |
43 | org.springframework.boot
44 | spring-boot-starter-test
45 | test
46 |
47 |
48 |
49 |
50 |
51 |
52 | org.springframework.boot
53 | spring-boot-maven-plugin
54 |
55 |
56 |
57 |
58 |
59 |
--------------------------------------------------------------------------------
/README.md:
--------------------------------------------------------------------------------
1 | # spring-boot-with-metrics
2 |
3 | This demo app shows how a Spring Boot application can expose a Prometheus metrics endpoint for scraping.
4 |
5 | - For Java 11+
6 |
7 | 🚼 The app was initially created with [Spring Initializr][init] and then by following the [RESTful service tutorial on spring.io][rest-tutorial].
8 |
9 | ## To run
10 |
11 | To run the app:
12 |
13 | mvn clean spring-boot:run
14 |
15 | This will expose Prometheus metrics at `/actuator/prometheus`. This is a simple `key value` listing of metrics. You can check them out using `curl`, for example:
16 |
17 | $ curl http://localhost:8080/actuator/prometheus
18 | # HELP process_uptime_seconds The uptime of the Java virtual machine
19 | # TYPE process_uptime_seconds gauge
20 | process_uptime_seconds 10.284
21 | # HELP jvm_threads_states_threads The current number of threads having NEW state
22 | # TYPE jvm_threads_states_threads gauge
23 | jvm_threads_states_threads{state="runnable",} 9.0
24 | jvm_threads_states_threads{state="blocked",} 0.0
25 | jvm_threads_states_threads{state="waiting",} 11.0
26 | ...
27 | # TYPE tomcat_sessions_alive_max_seconds gauge
28 | tomcat_sessions_alive_max_seconds 0.0
29 | ...
30 |
31 | Next, try accessing the API in the app at `http://localhost:8080/greeting` either in a web browser or using `curl`. Check the `/actuator/prometheus` endpoint again. You should see the `http_server_requests_seconds_sum` metric increase. You will also see a new metric `greeting_time_seconds` which is a custom metric added to the app:
32 |
33 | $ curl http://localhost:8080/actuator/prometheus | grep greeting_time_seconds
34 | # HELP greeting_time_seconds Time taken to return greeting
35 | # TYPE greeting_time_seconds summary
36 | greeting_time_seconds{class="com.tutorialworks.demos.springbootwithmetrics.GreetingController",exception="none",method="greeting",quantile="0.5",} 0.0
37 | greeting_time_seconds{class="com.tutorialworks.demos.springbootwithmetrics.GreetingController",exception="none",method="greeting",quantile="0.9",} 0.0
38 | ...
39 |
40 | ## Timing a custom method
41 |
42 | The method in the application which responds to the REST request has been annotated with `@Timed`, so Micrometer will capture the execution time of this method:
43 |
44 | ```java
45 | @GetMapping("/greeting")
46 | @Timed(value = "greeting.time", description = "Time taken to return greeting",
47 | percentiles = {0.5, 0.90})
48 | public Greeting greeting(@RequestParam(value = "name", defaultValue = "World") String name) {
49 | return new Greeting(counter.incrementAndGet(), String.format(template, name));
50 | }
51 | ```
52 |
53 | Once you make a request to the service at , you will also see a new metric exposed, `greeting_time_seconds` exposed, which shows the execution time of the `greeting` method:
54 |
55 | # HELP greeting_time_seconds Time taken to return greeting
56 | # TYPE greeting_time_seconds summary
57 | greeting_time_seconds{class="com.tutorialworks.demos.springbootwithmetrics.GreetingController",exception="none",met
58 | hod="greeting",quantile="0.9",} 0.02097152
59 | greeting_time_seconds_count{class="com.tutorialworks.demos.springbootwithmetrics.GreetingController",exception="non
60 | e",method="greeting",} 1.0
61 | greeting_time_seconds_sum{class="com.tutorialworks.demos.springbootwithmetrics.GreetingController",exception="none"
62 | ,method="greeting",} 0.021689345
63 | # HELP greeting_time_seconds_max Time taken to return greeting
64 | # TYPE greeting_time_seconds_max gauge
65 | greeting_time_seconds_max{class="com.tutorialworks.demos.springbootwithmetrics.GreetingController",exception="none",method="greeting",} 0.021689345
66 |
67 |
68 | From the [Micrometer docs][timerdocs]:
69 |
70 | > All implementations of _Timer_ report at least the total time and count of events as separate time series.
71 |
72 | ## Getting metrics into Prometheus
73 |
74 | Now we need to get these metrics into Prometheus.
75 |
76 | In another terminal, use Podman to start an ephemeral Prometheus in a container, and use the `host` networking option, which will allow the container to access the Spring Boot app on `localhost`:
77 |
78 | podman run --net=host \
79 | -v ./prometheus.yml:/etc/prometheus/prometheus.yml:Z \
80 | prom/prometheus
81 |
82 | Check the Prometheus console at .
83 |
84 | - Go to _Targets_, you should see the Spring Boot app being scraped successfully.
85 |
86 | - On the _Graph_ page, you should be able to type in a metric from the application (e.g. `tomcat_sessions_active_current_sessions`, or `greeting_time_seconds`) and see the raw data, or plot a graph
87 |
88 | ## Troubleshooting
89 |
90 | Inside the Prometheus container, you can check that you can access the Spring Boot metrics:
91 |
92 | $ podman exec -it sh
93 | $$ wget -S -O - http://localhost:8080/actuator/prometheus
94 |
95 |
96 | [rest-tutorial]: https://spring.io/guides/gs/rest-service/
97 | [init]: https://start.spring.io
98 | [timerdocs]: https://micrometer.io/docs/concepts#_timers
99 |
--------------------------------------------------------------------------------
/LICENSE:
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