Package com.linecorp.armeria.server.healthcheck

Interface HealthChecker

All Known Subinterfaces:

ListenableHealthChecker

All Known Implementing Classes:

SettableHealthChecker

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface HealthChecker

Determines whether the Server is healthy. All registered HealthCheckers must return true for the Server to be considered healthy.

Method Summary

Modifier and Type	Method	Description
boolean	isHealthy()	Returns true if and only if the Server is healthy.
static ListenableHealthChecker	of(Supplier<? extends CompletionStage<HealthCheckStatus>> healthChecker, Duration fallbackTtl)	Returns a newly created ListenableHealthChecker that invokes the specified health checker function repetitively on an arbitrary EventExecutor from CommonPools.workerGroup().
static ListenableHealthChecker	of(Supplier<? extends CompletionStage<HealthCheckStatus>> healthChecker, Duration fallbackTtl, EventExecutor eventExecutor)	Returns a newly created ListenableHealthChecker that invokes the specified health checker function repetitively on the specified EventExecutor.
static HealthChecker	ofCpu(double targetSystemCpuUsage, double targetProcessCpuUsage)	Creates a new instance of HealthChecker which reports health based on cpu usage reported by OperatingSystemMXBean.

Method Details

of

@UnstableApi
static ListenableHealthChecker of(Supplier<? extends CompletionStage<HealthCheckStatus>> healthChecker,
 Duration fallbackTtl)

Returns a newly created ListenableHealthChecker that invokes the specified health checker function repetitively on an arbitrary EventExecutor from CommonPools.workerGroup().

Parameters:

healthChecker - A Supplier that performs a health check asynchronously and returns a future that will complete with a HealthCheckStatus. HealthCheckStatus.ttlMillis() determines the delay before the next health check. If the future completed exceptionally, the specified fallbackTtl will be used instead to determine the delay. Supplier should avoid returning null or throwing exception. The CompletionStage from Supplier should avoid completing with null result or failing.

fallbackTtl - The amount of delay between each health check if the previous health check failed unexpectedly so it's not possible to determine how long we have to wait until the next health check.

See Also:

• of(Supplier, Duration, EventExecutor)

of

@UnstableApi
static ListenableHealthChecker of(Supplier<? extends CompletionStage<HealthCheckStatus>> healthChecker,
 Duration fallbackTtl,
 EventExecutor eventExecutor)

Returns a newly created ListenableHealthChecker that invokes the specified health checker function repetitively on the specified EventExecutor.

Parameters:

healthChecker - A Supplier that performs a health check asynchronously and returns a future that will complete with a HealthCheckStatus. HealthCheckStatus.ttlMillis() determines the delay before the next health check. If the future completed exceptionally, the specified fallbackTtl will be used instead to determine the delay. Supplier should avoid returning null or throwing exception. The CompletionStage from Supplier should avoid completing with null result or failing.

fallbackTtl - The amount of delay between each health check if the previous health check failed unexpectedly so it's not possible to determine how long we have to wait until the next health check.

eventExecutor - The EventExecutor that will invoke the specified healthChecker.

ofCpu

static HealthChecker ofCpu(double targetSystemCpuUsage,
 double targetProcessCpuUsage)

Creates a new instance of HealthChecker which reports health based on cpu usage reported by OperatingSystemMXBean. Both system and process cpu usage must be (inclusive) lower than the specified threshold in order for the HealthChecker to report as healthy. If the HealthChecker is unable to find a suitable OperatingSystemMXBean, an exception is thrown on construction.

Parameters:

targetSystemCpuUsage - Target system CPU usage as a percentage (0 - 1).

targetProcessCpuUsage - Target process CPU usage as a percentage (0 - 1).

Returns:

an instance of HealthChecker configured with the provided CPU usage targets.

isHealthy

boolean isHealthy()

Returns true if and only if the Server is healthy.