Better monitoring with Spring boot Actuator

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What is Spring boot Actuator? ● Spring boot library ● Adds production-ready features ● Provides useful endpoints ● Both over HTTP and JMX

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Which endpoints are there? ● Auditevents ● Beans ● Caches ● Conditions ● Conﬁgprops ● Env ● Flyway ● Health ● Heapdump ● Httptrace ● Info ● Integrationgraph ● Jolokia ● Logﬁle ● Loggers ● Liquibase ● Metrics ● Mappings ● Prometheus ● Scheduledtasks ● Sessions ● Shutdown ● Threaddump

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How do I get started?

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Add a dependency... org.springframework.boot spring-boot-starter-actuator

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… and conﬁgure what you need management: endpoints: web: exposure: include: env, info, health, metrics

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And… what now?

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Visit /actuator { "_links": { "self": { "href": "http://192.168.0.220:8080/actuator", "templated": false }, "health": { "href": "http://192.168.0.220:8080/actuator/health", "templated": false } }

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Exploring the conditions endpoint

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What does it do? ● Which autoconﬁgurations are in use ● Why are they (not) applied? ● What can I do to make it work?

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Visit /actuator/conditions { "positiveMatches": {/* ... */}, "negativeMatches": { "RabbitHealthContributorAutoConfiguration": { "notMatched": [ { "condition": "OnClassCondition", "message": "@ConditionalOnClass did not find required class 'org.springframework.amqp.rabbit.core.RabbitTemplate'" } ]

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Exploring the env endpoint

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What does it do? ● Which application properties are loaded? ● Where do these properties come from?

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Visit /actuator/env { "activeProfiles": [ "dev" ], "propertySources": [ { "name": "applicationConfig: [classpath:/application-dev.yml]", "properties": { "server.port": { "value": 8080, "origin": "class path resource [application-dev.yml]:2:9"

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Exploring the health endpoint

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What does it do? ● Is the database available? ● Is there enough disk space? ● Is Eureka available? ● Is Solr available? ● Useful for monitoring software ● ...

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Visit /actuator/health { "status": "UP" }

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Showing detailed health info management: endpoint: health: show-details: always

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Showing detailed health info { "status": "UP", "components": { "db": { "status": "UP", "details": { "database": "DB2 UDB for AS/400", "validationQuery": "SELECT 1 FROM SYSIBM.SYSDUMMY1", "result": 1 } }

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Creating a custom health indicator @Component @RequiredArgsConstructor public class GitHubAPIHealthIndicator implements HealthIndicator { private final RestTemplate restTemplate; @Override public Health health() { // TODO: implement } }

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Creating a custom health indicator try { var result = restTemplate.getForEntity("https://api.github.com/", ObjectNode.class); if (result.getStatusCode().is2xxSuccessful() && result.getBody() != null) { return Health.up().build(); } else { return Health.down().withDetail("status", result.getStatusCode()).build(); } } catch (RestClientException ex) { return Health.down().withException(ex).build(); }

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Creating a custom health indicator { "status": "UP", "components": { "gitHubAPI": { "status": "UP" } } }

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Useful for monitoring

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Useful for Eureka

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Exploring the heapdump endpoint

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What does it do? ● Returns *.HPROF ﬁle ● Can be imported in JVisualVM, … ● Find memory leaks and other peformance issues

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Open the *.HPROF ﬁle

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Exploring the info endpoint

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What does it do? ● Returns additional information ● By default empty ● Useful in combination with Maven resource ﬁltering

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Conﬁguring info info: contributors: Dimitri Mestdagh project-version: @project-version@ build-timestamp: @maven.build.timestamp@

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Visit /actuator/info { "contributors": "Dimitri Mestdagh", "project-version": "0.0.1-SNAPSHOT", "build-timestamp": "2020-06-27 11:52:30" }

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Exploring the loggers endpoint

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What does it do? ● What logging levels are in use? ● Change runtime logging levels ● Useful for debugging

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Visit /actuator/loggers { "loggers": { "ROOT": { "configuredLevel": "INFO", "effectiveLevel": "INFO" }, "be.g00glen00b": { "configuredLevel": null, "effectiveLevel": "INFO" } } }

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Changing the runtime logger levels curl \ --header "Content-Type: application/json" \ --request POST \ --data '{"configuredLevel": "DEBUG"}' \ http://localhost:8080/actuator/loggers/be.g00glen00b

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Exploring the metrics endpoint

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What does it do? ● Application metrics ● Uses micrometer ● Counters ● Gauges ● Distribution summaries ● Percentiles ● Timers

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Visit /actuator/metrics { "names": [ "cache.evictions", "http.server.requests", "jvm.threads.states", "hystrix.execution", "spring.batch.chunk.write", "spring.batch.item.process", "hystrix.latency.total", "jvm.memory.used" ] }

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Visit /actuator/metrics/{metric} { "name": "jvm.memory.used", "description": "The amount of used memory", "baseUnit": "bytes", "measurements": [{ "statistic": "VALUE", "value": 196616376 }], "availableTags": [{ "tag": "area", "values": ["heap", "nonheap"] }]

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Visit /actuator/metrics/{metric}?tag=area:heap { "name": "jvm.memory.used", "description": "The amount of used memory", "baseUnit": "bytes", "measurements": [{ "statistic": "VALUE", "value": 196616376 }], "availableTags": [] }

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Creating custom counter metrics @Bean public Counter invoicesCounter(MeterRegistry registry) { return Counter .builder("invoices.created") .description("Amount of invoices created") .register(registry); }

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Creating custom counter metrics @PostMapping public CreatedInvoiceDTO create(@RequestBody InvoiceParametersDTO parameters) { counter.increment(); // Add this return facade.create(parameters); }

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Creating custom gauge metrics @Bean public Gauge countOrdersGauge(MeterRegistry registry, OrderRepository repository) { return Gauge .builder("order.count", repository::count) .description("Amount of registered orders”) .register(registry); }

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Cool stuff… but why?

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Cool stuff… but why? ● Production-readiness ● Better monitoring ● Better logging ● Better debugging = More happy people

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Resources ● https://docs.spring.io/spring-boot/docs/current/reference/html/p roduction-ready-features.html ● https://dimitr.im/mastering-spring-boot-actuator Shameless self-promotion

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Thank you for listening!