Enabling distributed tracing in microservices with OpenTelemetry and Jaeger

 1// tag::copyright[]
 2/*******************************************************************************
 3 * Copyright (c) 2023 IBM Corporation and others.
 4 * All rights reserved. This program and the accompanying materials
 5 * are made available under the terms of the Eclipse Public License 2.0
 6 * which accompanies this distribution, and is available at
 7 * http://www.eclipse.org/legal/epl-2.0/
 8 *
 9 * SPDX-License-Identifier: EPL-2.0
10 *******************************************************************************/
11// end::copyright[]
12
13package io.openliberty.guides.inventory;
14
15import java.util.ArrayList;
16import java.util.Properties;
17
18import io.opentelemetry.instrumentation.annotations.WithSpan;
19import io.opentelemetry.instrumentation.annotations.SpanAttribute;
20
21import io.openliberty.guides.inventory.client.SystemClient;
22import io.openliberty.guides.inventory.model.InventoryList;
23import io.openliberty.guides.inventory.model.SystemData;
24import jakarta.enterprise.context.ApplicationScoped;
25import jakarta.inject.Inject;
26import java.util.List;
27import java.util.Collections;
28
29import org.eclipse.microprofile.config.inject.ConfigProperty;
30
31@ApplicationScoped
32public class InventoryManager {
33
34    @Inject
35    @ConfigProperty(name = "system.http.port")
36    private int SYSTEM_PORT;
37
38    private List<SystemData> systems = Collections.synchronizedList(new ArrayList<>());
39    private SystemClient systemClient = new SystemClient();
40
41    public Properties get(String hostname) {
42        systemClient.init(hostname, SYSTEM_PORT);
43        Properties properties = systemClient.getProperties();
44        return properties;
45    }
46
47    // tag::listWithSpan[]
48    @WithSpan
49    // end::listWithSpan[]
50    // tag::listMethod[]
51    public InventoryList list() {
52        return new InventoryList(systems);
53    }
54    // end::listMethod[]
55
56    // tag::addWithSpan[]
57    @WithSpan("Inventory Manager Add")
58    // end::addWithSpan[]
59    // tag::addMethod[]
60    // tag::spanAttribute[]
61    public void add(@SpanAttribute("hostname") String host,
62    // end::spanAttribute[]
63                    Properties systemProps) {
64        Properties props = new Properties();
65        props.setProperty("os.name", systemProps.getProperty("os.name"));
66        props.setProperty("user.name", systemProps.getProperty("user.name"));
67        SystemData system = new SystemData(host, props);
68        if (!systems.contains(system)) {
69            systems.add(system);
70        }
71    }
72    // end::addMethod[]
73
74    int clear() {
75        int propertiesClearedCount = systems.size();
76        systems.clear();
77        return propertiesClearedCount;
78    }
79}

  1// tag::copyright[]
  2/*******************************************************************************
  3 * Copyright (c) 2023 IBM Corporation and others.
  4 * All rights reserved. This program and the accompanying materials
  5 * are made available under the terms of the Eclipse Public License 2.0
  6 * which accompanies this distribution, and is available at
  7 * http://www.eclipse.org/legal/epl-2.0/
  8 *
  9 * SPDX-License-Identifier: EPL-2.0
 10 *******************************************************************************/
 11// end::copyright[]
 12package io.openliberty.guides.inventory;
 13
 14import java.util.Properties;
 15
 16import io.opentelemetry.api.trace.Tracer;
 17import io.opentelemetry.api.trace.Span;
 18import io.opentelemetry.context.Scope;
 19
 20import io.openliberty.guides.inventory.model.InventoryList;
 21import jakarta.enterprise.context.RequestScoped;
 22import jakarta.inject.Inject;
 23import jakarta.ws.rs.DELETE;
 24import jakarta.ws.rs.GET;
 25import jakarta.ws.rs.Path;
 26import jakarta.ws.rs.PathParam;
 27import jakarta.ws.rs.Produces;
 28import jakarta.ws.rs.core.MediaType;
 29import jakarta.ws.rs.core.Response;
 30
 31@RequestScoped
 32@Path("/systems")
 33public class InventoryResource {
 34
 35    // tag::manager[]
 36    @Inject
 37    private InventoryManager manager;
 38    // end::manager[]
 39
 40    // tag::inject[]
 41    @Inject
 42    private Tracer tracer;
 43    // end::inject[]
 44
 45    @GET
 46    @Path("/{hostname}")
 47    @Produces(MediaType.APPLICATION_JSON)
 48    public Response getPropertiesForHost(@PathParam("hostname") String hostname) {
 49        // tag::getPropertiesSpan[]
 50        Span getPropertiesSpan = tracer.spanBuilder("GettingProperties").startSpan();
 51        // end::getPropertiesSpan[]
 52        // tag::try[]
 53        Properties props = null;
 54        // tag::scope[]
 55        try (Scope scope = getPropertiesSpan.makeCurrent()) {
 56        // end::scope[]
 57            // tag::getSystem[]
 58            props = manager.get(hostname);
 59            // end::getSystem[]
 60            if (props == null) {
 61                // tag::addEvent1[]
 62                getPropertiesSpan.addEvent("Cannot get properties");
 63                // end::addEvent1[]
 64                return Response.status(Response.Status.NOT_FOUND)
 65                         .entity("{ \"error\" : \"Unknown hostname or the system "
 66                               + "service may not be running on " + hostname + "\" }")
 67                         .build();
 68            }
 69            // tag::addEvent2[]
 70            getPropertiesSpan.addEvent("Received properties");
 71            // end::addEvent2[]
 72            manager.add(hostname, props);
 73        } finally {
 74            // tag::end[]
 75            getPropertiesSpan.end();
 76            // end::end[]
 77        }
 78        // end::try[]
 79        return Response.ok(props).build();
 80
 81    }
 82
 83    @GET
 84    @Produces(MediaType.APPLICATION_JSON)
 85    public InventoryList listContents() {
 86        return manager.list();
 87    }
 88
 89    @DELETE
 90    @Produces(MediaType.APPLICATION_JSON)
 91    public Response clearContents() {
 92        int cleared = manager.clear();
 93
 94        if (cleared == 0) {
 95            return Response.status(Response.Status.NOT_MODIFIED)
 96                           .build();
 97        }
 98        return Response.status(Response.Status.OK)
 99                       .build();
100    }
101}