com.linecorp.armeria.server.healthcheck

Class HealthCheckService

java.lang.Object

com.linecorp.armeria.server.healthcheck.HealthCheckService

All Implemented Interfaces:

Unwrappable, HttpService, Service<HttpRequest,HttpResponse>, TransientHttpService, TransientService<HttpRequest,HttpResponse>

public final class HealthCheckService
extends Object
implements TransientHttpService

An HttpService that responds with HTTP status "200 OK" if the server is healthy and can accept requests and HTTP status "503 Service Not Available" if the server is unhealthy and cannot accept requests. The default behavior is to respond healthy after the server is started and unhealthy after it started to stop.

Long-polling support

A client that sends health check requests to this service can send a long-polling request to get notified immediately when a Server becomes healthy or unhealthy, rather than sending health check requests periodically.

To wait until a Server becomes unhealthy, i.e. wait for the failure, send an HTTP request with two additional headers:

• If-None-Match: "healthy"
• Prefer: wait=<seconds>
  • e.g. Prefer: wait=60

To wait until a Server becomes healthy, i.e. wait for the recovery, send an HTTP request with two additional headers:

• If-None-Match: "unhealthy"
• Prefer: wait=<seconds>

The Server will wait up to the amount of seconds specified in the "Prefer" header and respond with "200 OK", "503 Service Unavailable" or "304 Not Modified". "304 Not Modifies" signifies that the healthiness of the Server did not change. Once the response is received, the client is supposed to send a new long-polling request to continue watching the healthiness of the Server.

All health check responses will contain a "armeria-lphc" header whose value is the maximum allowed value of the "Prefer: wait=<seconds>" header. 0 means long polling has been disabled. "lphc" stands for long-polling health check.

See Also:

HealthCheckServiceBuilder

Method Summary

Modifier and Type	Method and Description
static HealthCheckServiceBuilder	builder() Returns a new builder which builds a new HealthCheckService.
static HealthCheckService	of(HealthChecker... healthCheckers) Returns a newly created HealthCheckService with the specified HealthCheckers.
static HealthCheckService	of(Iterable<? extends HealthChecker> healthCheckers) Returns a newly created HealthCheckService with the specified HealthCheckers.
HttpResponse	serve(ServiceRequestContext ctx, HttpRequest req) Serves an incoming Request.
void	serviceAdded(ServiceConfig cfg) Invoked when this service has been added to a Server with the specified configuration.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.linecorp.armeria.server.HttpService

decorate, decorate

Methods inherited from interface com.linecorp.armeria.server.Service

as, decorate, shouldCachePath

Method Detail

of

public static HealthCheckService of(HealthChecker... healthCheckers)

Returns a newly created HealthCheckService with the specified HealthCheckers.

of

public static HealthCheckService of(Iterable<? extends HealthChecker> healthCheckers)

Returns a newly created HealthCheckService with the specified HealthCheckers.

builder

public static HealthCheckServiceBuilder builder()

Returns a new builder which builds a new HealthCheckService.

serviceAdded

public void serviceAdded(ServiceConfig cfg)
                  throws Exception

Description copied from interface: Service

Invoked when this service has been added to a Server with the specified configuration. Please note that this method can be invoked more than once if this service has been added more than once.

Specified by:

serviceAdded in interface Service<HttpRequest,HttpResponse>

Throws:

Exception

serve

public HttpResponse serve(ServiceRequestContext ctx,
                          HttpRequest req)
                   throws Exception

Description copied from interface: Service

Serves an incoming Request.

Specified by:

serve in interface HttpService

Specified by:

serve in interface Service<HttpRequest,HttpResponse>

Parameters:

ctx - the context of the received Request

req - the received Request

Returns:

the Response

Throws:

Exception