Merge pull request #768 from elonzh/feat/prometheus-metrics

feat: support export metrics as prometheus format

build.gradle

@@ -347,6 +347,8 @@ project(":grobid-service") {
         implementation "io.dropwizard:dropwizard-auth:1.3.23"
         implementation "org.apache.pdfbox:pdfbox:2.0.3"
         implementation "javax.activation:activation:1.1.1"
+        implementation "io.prometheus:simpleclient_dropwizard:0.11.0"
+        implementation "io.prometheus:simpleclient_servlet:0.11.0"
 
         testImplementation "io.dropwizard:dropwizard-testing:1.3.17"
     }

grobid-service/src/main/java/org/grobid/service/main/GrobidServiceApplication.java

@@ -9,6 +9,8 @@
 import io.dropwizard.forms.MultiPartBundle;
 import io.dropwizard.setup.Bootstrap;
 import io.dropwizard.setup.Environment;
+import io.prometheus.client.dropwizard.DropwizardExports;
+import io.prometheus.client.exporter.MetricsServlet;
 import org.apache.commons.lang3.ArrayUtils;
 import org.eclipse.jetty.servlets.CrossOriginFilter;
 import org.grobid.service.GrobidServiceConfiguration;
@@ -18,6 +20,7 @@
 
 import javax.servlet.DispatcherType;
 import javax.servlet.FilterRegistration;
+import javax.servlet.ServletRegistration;
 import java.io.File;
 import java.util.Arrays;
 import java.util.EnumSet;
@@ -55,6 +58,9 @@ private List<? extends Module> getGuiceModules() {
     @Override
     public void run(GrobidServiceConfiguration configuration, Environment environment) {
         LOGGER.info("Service config={}", configuration);
+        new DropwizardExports(environment.metrics()).register();
+        ServletRegistration.Dynamic registration = environment.admin().addServlet("Prometheus", new MetricsServlet());
+        registration.addMapping("/metrics/prometheus");
         environment.jersey().setUrlPattern(RESOURCES + "/*");
 
         String allowedOrigins = configuration.getGrobid().getCorsAllowedOrigins();