fix(#2105): Retry mechanism without delay causing failures (#2108)

Co-authored-by: Liran M <[email protected]>

Author: placaze

spring-boot-admin-server/src/main/java/de/codecentric/boot/admin/server/services/IntervalCheck.java

@@ -80,7 +80,7 @@ public void start() {
 		this.subscription = Flux.interval(this.interval)
 				.doOnSubscribe((s) -> log.debug("Scheduled {}-check every {}", this.name, this.interval))
 				.log(log.getName(), Level.FINEST).subscribeOn(this.scheduler).concatMap((i) -> this.checkAllInstances())
-				.retryWhen(Retry.indefinitely()
+				.retryWhen(Retry.backoff(Long.MAX_VALUE, Duration.ofSeconds(1))
 						.doBeforeRetry((s) -> log.warn("Unexpected error in {}-check", this.name, s.failure())))
 				.subscribe();
 	}

spring-boot-admin-server/src/test/java/de/codecentric/boot/admin/server/services/IntervalCheckTest.java

@@ -88,7 +88,7 @@ public void should_check_after_error() throws InterruptedException {
 		when(this.checkFn.apply(any())).thenReturn(Mono.error(new RuntimeException("Test"))).thenReturn(Mono.empty());
 
 		this.intervalCheck.start();
-		Thread.sleep(100);
+		Thread.sleep(1500);
 		verify(this.checkFn, atLeast(2)).apply(InstanceId.of("Test"));
 	}