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common-smartgears/src/main/java/org/gcube/smartgears/extensions/resource/HealthResource.java

105 lines
3.1 KiB
Java

package org.gcube.smartgears.extensions.resource;
import static org.gcube.smartgears.Constants.application_json;
import static org.gcube.smartgears.extensions.HttpExtension.Method.GET;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Set;
import java.util.Timer;
import java.util.stream.Collectors;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.gcube.com.fasterxml.jackson.databind.ObjectMapper;
import org.gcube.common.health.api.HealthCheck;
import org.gcube.common.health.api.ReadinessChecker;
import org.gcube.smartgears.context.application.ApplicationContext;
import org.gcube.smartgears.extensions.ApiResource;
import org.gcube.smartgears.extensions.ApiSignature;
import org.gcube.smartgears.health.HealthManager;
import org.gcube.smartgears.health.HealthResponse;
import org.gcube.smartgears.health.HealthTask;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import io.github.classgraph.ClassGraph;
import io.github.classgraph.ClassInfo;
import io.github.classgraph.ClassInfoList;
import io.github.classgraph.ScanResult;
public class HealthResource extends ApiResource {
private static final long serialVersionUID = 1L;
private static Logger log = LoggerFactory.getLogger(HealthResource.class);
public static final String mapping = "/health";
private static final ApiSignature signature = handles(mapping).with(method(GET).produces(application_json));
private HealthManager manager;
private HealthTask task;
private Timer timer;
HealthResource() {
super(signature);
}
@Override
public void init(ApplicationContext context) throws Exception {
Set<Class<?>> annotatedReadiness;
try (ScanResult result = new ClassGraph().enableClassInfo().enableAnnotationInfo().scan()) {
ClassInfoList classInfos = result.getClassesWithAnnotation(ReadinessChecker.class.getName());
annotatedReadiness = classInfos.stream().map(ClassInfo::loadClass)
.filter(c -> HealthCheck.class.isAssignableFrom(c)).collect(Collectors.toSet());
}
manager = new HealthManager();
for (Class<?> readnessClass : annotatedReadiness)
try {
manager.register((HealthCheck) readnessClass.getDeclaredConstructor().newInstance());
log.info("added class {} to health manager", readnessClass.getCanonicalName());
} catch (Throwable e) {
log.error("healthChecker class {} cannot be instantiated", readnessClass.getCanonicalName(), e);
}
task = new HealthTask(manager);
timer = new Timer(true);
timer.scheduleAtFixedRate(task, 10000, 60000);
super.init(context);
}
public void stop() {
if (timer!=null)
timer.cancel();
}
@Override
public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
PrintWriter out = resp.getWriter();
resp.setContentType("application/json");
resp.setCharacterEncoding("UTF-8");
HealthResponse response = readiness();
new ObjectMapper().writeValue(out, response);
out.flush();
}
public HealthResponse readiness() {
return task.getResponse();
}
}