io.helidon.webserver.observe.spi.Observer Maven / Gradle / Ivy
/*
* Copyright (c) 2023, 2024 Oracle and/or its affiliates.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.helidon.webserver.observe.spi;
import java.util.List;
import java.util.function.UnaryOperator;
import io.helidon.common.config.NamedService;
import io.helidon.webserver.http.HttpRouting;
import io.helidon.webserver.observe.ObserverConfigBase;
import io.helidon.webserver.spi.ServerFeature;
/**
* An observer adds observability feature to Helidon {@link io.helidon.webserver.observe.ObserveFeature},
* such as health, metrics.
*
* An observer may register features, services, filters on routing, or do some other magic that is related to
* observability. Some observers may expose endpoints, some may use a push approach.
*
* Configuration of an observer is located under {@code observe.observer} root configuration node, with
* {@link io.helidon.webserver.observe.spi.ObserveProvider#configKey()} key below it.
*/
public interface Observer extends NamedService {
/**
* Configuration of this observer.
*
* @return configuration of the observer
*/
ObserverConfigBase prototype();
/**
* Type of this observer, to make sure we do not configure an observer both from {@link java.util.ServiceLoader} and
* using programmatic approach.
* If it is desired to have more than one observer of the same type, always use programmatic approach
*
* @return type of this observer, should match {@link io.helidon.webserver.observe.spi.ObserveProvider#type()}
*/
@Override
String type();
@Override
default String name() {
return prototype().name();
}
/**
* Register the observer features, services, and/or filters.
* This is used by the observe feature.
* Do NOT use this method directly, kindly start with {@link io.helidon.webserver.observe.ObserveFeature} and register
* it with the server builder.
*
* Implementations of observers should register all they need through an {@link io.helidon.webserver.http.HttpFeature},
* to make sure the weight of the {@link io.helidon.webserver.observe.ObserveFeature} is honored when routing is
* set up. If you do not use an HttpFeature, the registration will always happen later than the default (business) routing
* feature.
*
* @param featureContext access to all routing builders, for cases where this observer needs to register additional
* components to other sockets
* @param observeEndpointRouting routing builders that expose observability endpoints, and this feature must use these to
* register any endpoints exposed for observability
* @param endpointFunction function to obtain the final endpoint for observers that expose observe endpoints (such as
* {@code /observe/health} would be provider for {@code health} by default)
*/
void register(ServerFeature.ServerFeatureContext featureContext,
List observeEndpointRouting,
UnaryOperator endpointFunction);
}