Add /info URL to provide information about server application

core/src/main/java/com/linecorp/armeria/server/management/AppInfo.java

@@ -0,0 +1,100 @@
+/*
+ * Copyright 2024 LINE Corporation
+ *
+ * LINE Corporation licenses this file to you 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:
+ *
+ *   https://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 com.linecorp.armeria.server.management;
+
+import java.util.Objects;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.common.base.MoreObjects;
+
+import com.linecorp.armeria.common.annotation.Nullable;
+
+/**
+ * A class that represents application information, which can be configured through
+ * {@link ManagementService#of(AppInfo)}.
+ */
+public final class AppInfo {
+    @Nullable final String version;
+    @Nullable final String name;
+    @Nullable final String description;
+
+    /**
+     * Creates a new {@link AppInfo} that holds information about an application.
+     * @param version A version of an application e.g. "1.0.0"
+     * @param name A name of an application
+     * @param description A description of application
+     */
+    public AppInfo(@Nullable String version, @Nullable String name, @Nullable String description) {
+        this.version = version;
+        this.name = name;
+        this.description = description;
+    }
+
+    /**
+     * Returns the artifact version of the deployed application, such as {@code "1.0.0"}.
+     */
+    @JsonProperty
+    public String getVersion() {
+        return version;
+    }
+
+    /**
+     * Returns the name of the deployed application.
+     */
+    @JsonProperty
+    public String getName() {
+        return name;
+    }
+
+    /**
+     * Returns the description of the deployed application.
+     */
+    @JsonProperty
+    public String getDescription() {
+        return description;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(this)
+                .add("version", version)
+                .add("name", name)
+                .add("description", description)
+                .toString();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+
+        final AppInfo appInfo = (AppInfo) o;
+        return Objects.equals(version, appInfo.version) &&
+               Objects.equals(name, appInfo.name) &&
+               Objects.equals(description, appInfo.description);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(version, name, description);
+    }
+}

core/src/main/java/com/linecorp/armeria/server/management/AppInfoService.java

@@ -0,0 +1,101 @@
+/*
+ * Copyright 2024 LINE Corporation
+ *
+ * LINE Corporation licenses this file to you 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:
+ *
+ *   https://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 com.linecorp.armeria.server.management;
+
+import static java.util.Objects.requireNonNull;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.google.common.collect.ImmutableMap;
+
+import com.linecorp.armeria.common.AggregatedHttpResponse;
+import com.linecorp.armeria.common.HttpRequest;
+import com.linecorp.armeria.common.HttpResponse;
+import com.linecorp.armeria.common.HttpStatus;
+import com.linecorp.armeria.common.MediaType;
+import com.linecorp.armeria.common.annotation.Nullable;
+import com.linecorp.armeria.common.util.Version;
+import com.linecorp.armeria.internal.common.JacksonUtil;
+import com.linecorp.armeria.server.HttpService;
+import com.linecorp.armeria.server.Server;
+import com.linecorp.armeria.server.ServiceRequestContext;
+
+/**
+ * An {@link HttpService} that provides additional information about configured server.
+ * This functionality is can be used by binding {@link ManagementService}
+ * It provides information about not only deployed application information, which can be specified by user,
+ * but also one about Armeria artifact itself.
+ */
+public enum AppInfoService implements HttpService {
+
+    INSTANCE;
+
+    private static final Version armeriaVersionInfo = Version.get("armeria", Server.class.getClassLoader());
+
+    @Nullable
+    private AggregatedHttpResponse infoAggregatedResponse;
+
+    void setAppInfo(@Nullable AppInfo appInfo) {
+        final byte[] data;
+
+        try {
+            if (appInfo == null) {
+                data = JacksonUtil.writeValueAsBytes(buildArmeriaInfoMap());
+            } else {
+                data = JacksonUtil.writeValueAsBytes(buildInfoMap(appInfo));
+            }
+        } catch (JsonProcessingException e) {
+            throw new IllegalArgumentException(e.toString(), e);
+        }
+
+        infoAggregatedResponse = AggregatedHttpResponse.of(HttpStatus.OK, MediaType.JSON, data);
+    }
+
+    @Override
+    public HttpResponse serve(ServiceRequestContext ctx, HttpRequest req) throws Exception {
+        assert infoAggregatedResponse != null;
+        return infoAggregatedResponse.toHttpResponse();
+    }
+
+    private static ImmutableMap<Object, Object> buildInfoMap(AppInfo appInfo) {
+        requireNonNull(appInfo, "appInfo");
+        return ImmutableMap.builder()
+                    .putAll(buildArmeriaInfoMap())
+                    .putAll(buildAppInfoMap(appInfo))
+                    .build();
+    }
+
+    private static ImmutableMap<String, ImmutableMap<String, String>> buildArmeriaInfoMap() {
+        return ImmutableMap.of(
+                "armeria", ImmutableMap.of(
+                        "version", armeriaVersionInfo.artifactVersion(),
+                        "commit", armeriaVersionInfo.longCommitHash(),
+                        "repositoryStatus", armeriaVersionInfo.repositoryStatus()
+                )
+        );
+    }
+
+    private static ImmutableMap<String, ImmutableMap<String, String>> buildAppInfoMap(AppInfo appInfo) {
+        requireNonNull(appInfo, "appInfo");
+        return ImmutableMap.of(
+                "app", ImmutableMap.of(
+                        "version", appInfo.version,
+                        "name", appInfo.name,
+                        "description", appInfo.description
+                )
+        );
+    }
+}

core/src/main/java/com/linecorp/armeria/server/management/ManagementService.java

@@ -16,6 +16,8 @@
 
 package com.linecorp.armeria.server.management;
 
+import static java.util.Objects.requireNonNull;
+
 import com.linecorp.armeria.common.HttpHeaderNames;
 import com.linecorp.armeria.common.HttpRequest;
 import com.linecorp.armeria.common.HttpResponse;
@@ -64,6 +66,16 @@ public final class ManagementService extends AbstractHttpService {
      * Returns a singleton {@link ManagementService}.
      */
     public static ManagementService of() {
+        AppInfoService.INSTANCE.setAppInfo(null);
+        return INSTANCE;
+    }
+
+    /**
+     * Returns a singleton {@link ManagementService} with specified {@link AppInfo}.
+     */
+    public static ManagementService of(AppInfo appInfo) {
+        requireNonNull(appInfo, "appInfo");
+        AppInfoService.INSTANCE.setAppInfo(appInfo);
         return INSTANCE;
     }
 
@@ -77,6 +89,8 @@ public HttpResponse doGet(ServiceRequestContext ctx, HttpRequest req) throws Exc
                 return ThreadDumpService.INSTANCE.serve(ctx, req);
             case "/jvm/heapdump":
                 return HeapDumpService.INSTANCE.serve(ctx, req);
+            case "/info":
+                return AppInfoService.INSTANCE.serve(ctx, req);
             default:
                 return HttpResponse.of(HttpStatus.NOT_FOUND);
         }

core/src/test/java/com/linecorp/armeria/server/management/ManagementServiceTest.java

@@ -25,6 +25,8 @@
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.RegisterExtension;
 
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
 import com.linecorp.armeria.client.WebClient;
@@ -43,13 +45,16 @@
 
 class ManagementServiceTest {
     private static final ObjectMapper mapper = new ObjectMapper();
+    private static final AppInfo TEST_APP_INFO = new AppInfo(
+            "1.0.0", "test-app-name", "test-app-description"
+    );
 
     @RegisterExtension
     static ServerExtension server = new ServerExtension() {
         @Override
         protected void configure(ServerBuilder sb) {
             sb.requestTimeout(Duration.ofSeconds(45)); // Heap dump can take time.
-            sb.serviceUnder("/internal/management", ManagementService.of());
+            sb.serviceUnder("/internal/management", ManagementService.of(TEST_APP_INFO));
         }
     };
 
@@ -103,4 +108,22 @@ void heapDump() throws InterruptedException {
         // Make sure that the returned file has a valid hprof format
         assertThat(Arrays.copyOf(actual, fileHeader.length)).isEqualTo(fileHeader);
     }
+
+    @Test
+    void appInfo() throws JsonProcessingException {
+        final WebClient client = WebClient.builder(server.httpUri())
+                                          .build();
+
+        final AggregatedHttpResponse response = client.get("/internal/management/info").aggregate().join();
+        final String content = response.contentUtf8();
+        final JsonNode jsonNode = mapper.readTree(content).path("app");
+
+        final String actualVersion = jsonNode.path("version").textValue();
+        final String actualName = jsonNode.path("name").textValue();
+        final String actualDescription = jsonNode.path("description").textValue();
+
+        assertThat(actualVersion).isEqualTo(TEST_APP_INFO.version);
+        assertThat(actualName).isEqualTo(TEST_APP_INFO.name);
+        assertThat(actualDescription).isEqualTo(TEST_APP_INFO.description);
+    }
 }