I am scheduling a task that runs at fixed rate in Spring boot. The function that I am using to schedule a a task is as below:
private void scheduleTask(Store store, int frequency) {
final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);
Runnable task = store::scan;
scheduler.scheduleAtFixedRate(task, 0, frequency, TimeUnit.MILLISECONDS);
}
This works fine but if if there is an exception at application startup, the application should exit on exception. What is happening is that I get the exception in the log and the message "Application Failed to start" but looks like the scheduler shows as still running although it looks like only the scheduled thread is still running.
Any hints on how to properly schedule an asynchronous task in a Spring boot application? I tried the #Scheduled annotation but it does not run at all.
The #Scheduled should work. Have you added the #EnabledScheduling annotation to a #Configuration or the #SpringBootApplication? The Scheduling Getting Started explains it in detail.
Regarding the scheduleTask method: What calls that? Is it started outside the Spring context? If yes then Spring won't stop it. You have to take care of the lifecycle.
You should try to use the #Scheduled as it will manage the thread pools/executors for you and most people will find it easier to understand.
I have an external requirement that I provide an endpoint to tell the load balancer to send traffic to my app. Much like the Kubernetes "readiness" probe, but it has to be a certain format and path, so I can just give them the actuator health endpoint.
In the past I've used the HealthEndpoint and called health(), but that doesn't work for reactive apps. Is there a more flexible way to see if the app is "UP"? At this level I don't care if it's reactive or servlet, I just want to know what Spring Boot says about the app.
I haven't found anything like this, most articles talk about calling /actuator/health, but that isn't what I need.
Edit:
Just a bit more detail, I have to return a certain string "NS_ENABLE" if it's good. There are certain conditions where I return "NS_DISABLE", so I can't just not return anything, which would normally make sense.
Also, I really like how Spring Boot does the checking for me. I'd rather not re-implement all those checks.
Edit 2: My final solution
The answers below got me very far along even though it wasn't my final solution, so I wanted to give a hint to my final understanding.
It turns out that the HealthEndpoint works for reactive apps just as well as servlet apps, you just have to wrap them in Mono.
How do we define health of any web servers?
We look at how our dependent services are, we check the status of Redis, MySQL, MongoDB, ElasticSearch, and other databases, this's what actuator does internally.
Actuator checks the status of different databases and based on that it returns Up/Down.
You can implement your own methods that would check the health of dependent services.
Redis is healthy or not can be checked using ping command
MySQL can be verified using SELECT 1 command or run some query that should always success like SHOW TABLES
Similarly, you can implement a health check for other services. If you find all required services are up then you can declare up otherwise down.
What about shutdown triggers? Whenever your server receives a shutdown signal than no matter what's the state of your dependent services, you should always say down, so that upstream won't send a call to this instance.
Edit
The health of the entire spring app can be checked programmatically by autowiring one or more beans from the Actuator module.
#Controller
public class MyHealthController{
#Autowired private HealthEndpoint healthEndpoint;
#GetMapping("health")
public Health health() {
Health health = healthEndpoint.health();
return healthEndpoint.health();
}
}
There're other beans related to health check, we can auto wire required beans. Some of the beans provide the health of the respective component, we can combine the health of each component using HealthAggregator to get the final Health. All registered health indicator components can be accessed via HealthIndicatorRegistry.
#Controller
public class MyHealthController{
#Autowired private HealthAggregator healthAggregator;
#Autowired private HealthIndicatorRegistry healthIndicatorRegistry;
#GetMapping("health")
public Health health() {
Map<String, Health> health = new HashMap<>();
for (Entry<String, HealthIndicator> entry : healthIndicatorRegistry.getAll().entrySet()) {
health.put(entry.getKey(), entry.getValue().health());
}
return healthAggregator.aggregate(health);
}
}
NOTE: Reactive component has its own health indicator. Useful classes are ReactiveHealthIndicatorRegistry, ReactiveHealthIndicator etc
Simple solution is to write your own health endpoint instead of depending on Spring.
Spring Boot provides you production-ready endpoints but if it doesn't satisfy your purpose, write your end-point. It will just return "UP" in response. If the service is down, it will not return anything.
Here's the spring boot documentation on writing reactive health endpoints. Folow the guide and should be enough for your usecase.
They also document on how to write liveliness and Readiness of your application.
https://docs.spring.io/spring-boot/docs/current/reference/html/production-ready-features.html#reactive-health-indicators
I have a Spring Boot 2.0 application and I like to send Micrometer info to a graphite via statsd.
In the application.properties file I added:
management.metrics.export.statsd.host=192.168.1.1 // not the real IP
management.metrics.export.statsd.port=8126
management.metrics.export.statsd.step=10s
In one of the Akka actors classes I added
public class ThePrincessBride extends AbstractActor {
private final Counter Inigo =
Metrics.counter("my.name.is", "Inigo", "Montoya");
///
...
///
private void doX(){
//do X
Inigo.increment();
}
The problem is that I don't see this information in Graphite.
I also don't see any relevant network packets leaving my computer when checking the network packets with Wireshark.
Is it because some missing or wrong configuration?
Is it because of some conjunction with the Akka actor?
Do I need some daemon / client on my computer that the program needs to connect to?
It seems like the dependency micrometer-registry-graphite is simply not on the runtime classpath. Add that dependency and you should be good!
Using Spring Boot 2.0.0.RELEASE on Google Appengine Standard. Using autoscaling but trying to get some control about creation/destruction of the instances. Need to be able to do some cleanup and would like to log those events.
Any methods in Spring Boot like #Predestroy or ContextClosedEvent don't seem to work on GAE.
According to the documention, it should be possible to detect shutdown of an instance by adding a shutdown hook.
Documentation LifecycleManager.ShutdownHook.
Have tried to put it in several places without success.
Example as a #Bean:
#Bean
public LifecycleManager lifecycleManager() {
LifecycleManager lifecycle_manager = LifecycleManager.getInstance();
lifecycle_manager.setShutdownHook(new ShutdownHook() {
public void shutdown() {
LifecycleManager.getInstance().interruptAllRequests();
log.error("Shutdown " + getClassSimpleName() + ".");
}
});
log.warn("Created shutdown hook.");
return lifecycle_manager;
}
Shutdown hook is properly installed, but doesn't get fired when the instance goes down.
As you can read in the Google Issue Tracker:
Shutdown hooks only work for manual scaled instances on the standard runtime (...).
The shutdown hooks simply don't work on automatic and basic scaling.
I am trying to integrate the Brave MySql Instrumentation into my Spring Boot 2.x service to automatically let its interceptor enrich my traces with spans concerning MySql-Queries.
The current Gradle-Dependencies are the following
compile 'io.zipkin.zipkin2:zipkin:2.4.5'
compile('io.zipkin.reporter2:zipkin-sender-okhttp3:2.3.1')
compile('io.zipkin.brave:brave-instrumentation-mysql:4.14.3')
compile('org.springframework.cloud:spring-cloud-starter-zipkin:2.0.0.M5')
I already configured Sleuth successfully to send traces concerning HTTP-Request to my Zipkin-Server and now I wanted to add some spans for each MySql-Query the service does.
The TracingConfiguration it this:
#Configuration
public class TracingConfiguration {
/** Configuration for how to send spans to Zipkin */
#Bean
Sender sender() {
return OkHttpSender.create("https://myzipkinserver.com/api/v2/spans");
}
/** Configuration for how to buffer spans into messages for Zipkin */
#Bean AsyncReporter<Span> spanReporter() {
return AsyncReporter.create(sender());
}
#Bean Tracing tracing(Reporter<Span> spanListener) {
return Tracing.newBuilder()
.spanReporter(spanReporter())
.build();
}
}
The Query-Interceptor works properly, but my problem now is that the spans are not added to the existing trace but each are added to a new one.
I guess its because of the creation of a new sender/reporter in the configuration, but I have not been able to reuse the existing one created by the Spring Boot Autoconfiguration.
That would moreover remove the necessity to redundantly define the Zipkin-Url (because it is already defined for Zipkin in my application.yml).
I already tried autowiring the Zipkin-Reporter to my Bean, but all I got is a SpanReporter - but the Brave-Tracer-Builder requries a Reporter<Span>
Do you have any advice for me how to properly wire things up?
Please use latest snapshots. Sleuth in latest snapshots uses brave internally so integration will be extremely simple.