Package org.apache.juneau.rest.server.health

Class HealthServlet

java.lang.Object

jakarta.servlet.GenericServlet

jakarta.servlet.http.HttpServlet

org.apache.juneau.rest.server.servlet.RestServlet

org.apache.juneau.rest.server.servlet.BasicRestServlet

org.apache.juneau.rest.server.health.HealthServlet

All Implemented Interfaces:

jakarta.servlet.Servlet, jakarta.servlet.ServletConfig, Serializable, BasicUniversalConfig, DefaultConfig, DefaultHtmlConfig

public class HealthServlet
extends BasicRestServlet

Servlet flavor of the built-in health/readiness/liveness probe capability.

Mounts as a standalone top-level servlet at /healthz, /readyz, and /livez, delegating to a shared HealthAggregator worker bean. The HealthMixin mixin flavor delegates to the same bean, so the two forms cannot drift.

See Also:

• HealthMixin
• HealthAggregator

Since:

10.0.0

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.juneau.rest.server.servlet.RestServlet

RestServlet.Builder<R extends RestServlet,SELF extends RestServlet.Builder<R,SELF>>, RestServlet.DefaultBuilder<R extends RestServlet>

Field Summary

Fields inherited from class jakarta.servlet.http.HttpServlet

LEGACY_DO_HEAD

Constructor Summary

Constructors

Constructor	Description
HealthServlet()

Method Summary

Modifier and Type	Method	Description
protected Map<String,HealthIndicator>	indicators()	Returns the indicators to evaluate for this request.
void	initReadinessState(WritableBeanStore beanStore)	Registers the published readiness state (if any) into this resource's own bean store, so HealthAggregator.aggregate(org.apache.juneau.rest.server.RestContext, java.util.Map<java.lang.String, org.apache.juneau.rest.server.health.HealthIndicator>, org.apache.juneau.rest.server.health.HealthProbe, org.apache.juneau.rest.server.RestResponse) resolves the lifecycle-owned instance instead of falling back to ReadinessState.shared().
HealthAggregator.HealthResponse	probe(RestRequest req, RestResponse res)	Health/readiness/liveness probe endpoint.
protected HealthProbe	probeFor(RestRequest req)	Resolves which probe this request is for, keyed off the LAST PATH SEGMENT.
HealthServlet	publishReadinessState(ReadinessState state)	Publishes the lifecycle-owned ReadinessState that this probe should observe.

Methods inherited from class org.apache.juneau.rest.server.servlet.RestServlet

builder, createAuthenticator, destroy, doLog, getContext, getPath, getPaths, getRequest, getResponse, getRestBuilder, init, log, log, service, setContext

Methods inherited from class jakarta.servlet.http.HttpServlet

doDelete, doGet, doHead, doOptions, doPatch, doPost, doPut, doTrace, getLastModified, isSensitiveHeader, service

Methods inherited from class jakarta.servlet.GenericServlet

getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

Methods inherited from class java.lang.Object

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

Constructor Details

HealthServlet

public HealthServlet()

Method Details

publishReadinessState

public HealthServlet publishReadinessState(ReadinessState state)

Publishes the lifecycle-owned ReadinessState that this probe should observe.

Called by the embedded-server lifecycle component (e.g. JettyServerComponent, TomcatServerComponent) before the server starts, so the per-service instance that component flips on shutdown is registered into this resource's own bean store — see initReadinessState(org.apache.juneau.commons.inject.WritableBeanStore) — closing the gap between the microservice's bean store and this servlet's bean store that HealthAggregator consults.

Parameters:

state - The per-service readiness state. Ignored if null.

Returns:

This object.

initReadinessState

public void initReadinessState(WritableBeanStore beanStore)

Registers the published readiness state (if any) into this resource's own bean store, so HealthAggregator.aggregate(org.apache.juneau.rest.server.RestContext, java.util.Map<java.lang.String, org.apache.juneau.rest.server.health.HealthIndicator>, org.apache.juneau.rest.server.health.HealthProbe, org.apache.juneau.rest.server.RestResponse) resolves the lifecycle-owned instance instead of falling back to ReadinessState.shared().

Parameters:

beanStore - This resource's bean store.

probe

public HealthAggregator.HealthResponse probe(RestRequest req,
 RestResponse res)

Health/readiness/liveness probe endpoint.

Serves all three mount paths (/healthz, /readyz, /livez) through one /* operation, dispatching on the request's last path segment. A single zero-part, hasRemainder=true matcher is required because this servlet is auto-mounted at three exact-match top-level path-specs: a real container delivers a bare GET /readyz with a zero-segment pathInfo that no 1-segment matcher can satisfy, so three separate @RestGet(path="/{probe}") operations all 404. The last-path-segment key (probeFor(org.apache.juneau.rest.server.RestRequest)) is the only thing that differs per mount, so it is the disambiguator.

This replaces the former healthz(...)/readyz(...)/livez(...) entry points; subclasses that overrode any of those must override probeFor(RestRequest) (or this method) instead.

Parameters:

req - The request (its last path segment selects the probe).

res - The response.

Returns:

Aggregated health payload.

probeFor

protected HealthProbe probeFor(RestRequest req)

Resolves which probe this request is for, keyed off the LAST PATH SEGMENT.

Prefers HttpServletRequestWrapper.getPathInfo() when it carries a real (non-root) value — this is what MockRestClient and any remainder-based remount populate (servletPath="", pathInfo="/readyz"). Falls back to RestRequest.getServletPath() for a real container's bare exact-match hit, where pathInfo is null (servletPath="/readyz", pathInfo=null).

Parameters:

req - The request.

Returns:

The resolved probe, or null for /healthz (the overall aggregate).

indicators

protected Map<String,HealthIndicator> indicators()

Returns the indicators to evaluate for this request.

Defaults to every HealthIndicator bean registered in this resource's bean store. Subclasses may override to supply a fixed indicator set.

Returns:

Indicator map keyed by bean name.