HBASE-25895 Implement a Cluster Metrics JSON endpoint

Publishes a set of JSON endpoints following a RESTful structure, which expose a subset of the
`o.a.h.h.ClusterMetrics` object tree. The URI structure is as follows

    /api/v1/admin/cluster_metrics
    /api/v1/admin/cluster_metrics/live_servers
    /api/v1/admin/cluster_metrics/dead_servers

Signed-off-by: Sean Busbey <[email protected]>
Signed-off-by: Andrew Purtell <[email protected]>

Author: ndimiduk

hbase-http/src/main/java/org/apache/hadoop/hbase/http/HttpServer.java

@@ -39,6 +39,7 @@
 import javax.servlet.Filter;
 import javax.servlet.FilterChain;
 import javax.servlet.FilterConfig;
+import javax.servlet.Servlet;
 import javax.servlet.ServletContext;
 import javax.servlet.ServletException;
 import javax.servlet.ServletRequest;
@@ -838,6 +839,17 @@ public void addUnprivilegedServlet(String name, String pathSpec,
     addServletWithAuth(name, pathSpec, clazz, false);
   }
 
+  /**
+   * Adds a servlet in the server that any user can access. This method differs from
+   * {@link #addPrivilegedServlet(String, ServletHolder)} in that any authenticated user
+   * can interact with the servlet added by this method.
+   * @param pathSpec The path spec for the servlet
+   * @param holder The servlet holder
+   */
+  public void addUnprivilegedServlet(String pathSpec, ServletHolder holder) {
+    addServletWithAuth(pathSpec, holder, false);
+  }
+
   /**
    * Adds a servlet in the server that only administrators can access. This method differs from
    * {@link #addUnprivilegedServlet(String, String, Class)} in that only those authenticated user
@@ -848,6 +860,16 @@ public void addPrivilegedServlet(String name, String pathSpec,
     addServletWithAuth(name, pathSpec, clazz, true);
   }
 
+  /**
+   * Adds a servlet in the server that only administrators can access. This method differs from
+   * {@link #addUnprivilegedServlet(String, ServletHolder)} in that only those
+   * authenticated user who are identified as administrators can interact with the servlet added by
+   * this method.
+   */
+  public void addPrivilegedServlet(String pathSpec, ServletHolder holder) {
+    addServletWithAuth(pathSpec, holder, true);
+  }
+
   /**
    * Internal method to add a servlet to the HTTP server. Developers should not call this method
    * directly, but invoke it via {@link #addUnprivilegedServlet(String, String, Class)} or
@@ -859,6 +881,16 @@ void addServletWithAuth(String name, String pathSpec,
     addFilterPathMapping(pathSpec, webAppContext);
   }
 
+  /**
+   * Internal method to add a servlet to the HTTP server. Developers should not call this method
+   * directly, but invoke it via {@link #addUnprivilegedServlet(String, ServletHolder)} or
+   * {@link #addPrivilegedServlet(String, ServletHolder)}.
+   */
+  void addServletWithAuth(String pathSpec, ServletHolder holder, boolean requireAuthz) {
+    addInternalServlet(pathSpec, holder, requireAuthz);
+    addFilterPathMapping(pathSpec, webAppContext);
+  }
+
   /**
    * Add an internal servlet in the server, specifying whether or not to
    * protect with Kerberos authentication.
@@ -867,17 +899,33 @@ void addServletWithAuth(String name, String pathSpec,
    * servlets added using this method, filters (except internal Kerberos
    * filters) are not enabled.
    *
-   * @param name The name of the servlet (can be passed as null)
-   * @param pathSpec The path spec for the servlet
-   * @param clazz The servlet class
-   * @param requireAuth Require Kerberos authenticate to access servlet
+   * @param name The name of the {@link Servlet} (can be passed as null)
+   * @param pathSpec The path spec for the {@link Servlet}
+   * @param clazz The {@link Servlet} class
+   * @param requireAuthz Require Kerberos authenticate to access servlet
    */
   void addInternalServlet(String name, String pathSpec,
-      Class<? extends HttpServlet> clazz, boolean requireAuthz) {
+    Class<? extends HttpServlet> clazz, boolean requireAuthz) {
     ServletHolder holder = new ServletHolder(clazz);
     if (name != null) {
       holder.setName(name);
     }
+    addInternalServlet(pathSpec, holder, requireAuthz);
+  }
+
+  /**
+   * Add an internal servlet in the server, specifying whether or not to
+   * protect with Kerberos authentication.
+   * Note: This method is to be used for adding servlets that facilitate
+   * internal communication and not for user facing functionality. For
+   * servlets added using this method, filters (except internal Kerberos
+   * filters) are not enabled.
+   *
+   * @param pathSpec The path spec for the {@link Servlet}
+   * @param holder The object providing the {@link Servlet} instance
+   * @param requireAuthz Require Kerberos authenticate to access servlet
+   */
+  void addInternalServlet(String pathSpec, ServletHolder holder, boolean requireAuthz) {
     if (authenticationEnabled && requireAuthz) {
       FilterHolder filter = new FilterHolder(AdminAuthorizedFilter.class);
       filter.setName(AdminAuthorizedFilter.class.getSimpleName());

hbase-http/src/main/java/org/apache/hadoop/hbase/http/InfoServer.java

@@ -1,4 +1,4 @@
-/**
+/*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
@@ -19,18 +19,16 @@
 
 import java.io.IOException;
 import java.net.URI;
-
 import javax.servlet.ServletContext;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
-
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.CommonConfigurationKeys;
 import org.apache.hadoop.hbase.HBaseConfiguration;
 import org.apache.hadoop.security.authorize.AccessControlList;
 import org.apache.yetus.audience.InterfaceAudience;
-
 import org.apache.hbase.thirdparty.com.google.common.net.HostAndPort;
+import org.apache.hbase.thirdparty.org.eclipse.jetty.servlet.ServletHolder;
 
 /**
  * Create a Jetty embedded server to answer http requests. The primary goal
@@ -128,6 +126,7 @@ public void addServlet(String name, String pathSpec,
   }
 
   /**
+   * Adds a servlet in the server that any user can access.
    * @see HttpServer#addUnprivilegedServlet(String, String, Class)
    */
   public void addUnprivilegedServlet(String name, String pathSpec,
@@ -136,6 +135,18 @@ public void addUnprivilegedServlet(String name, String pathSpec,
   }
 
   /**
+   * Adds a servlet in the server that any user can access.
+   * @see HttpServer#addUnprivilegedServlet(String, ServletHolder)
+   */
+  public void addUnprivilegedServlet(String name, String pathSpec, ServletHolder holder) {
+    if (name != null) {
+      holder.setName(name);
+    }
+    this.httpServer.addUnprivilegedServlet(pathSpec, holder);
+  }
+
+  /**
+   * Adds a servlet in the server that any user can access.
    * @see HttpServer#addPrivilegedServlet(String, String, Class)
    */
   public void addPrivilegedServlet(String name, String pathSpec,

hbase-http/src/main/java/org/apache/hadoop/hbase/http/gson/ByteArraySerializer.java

@@ -0,0 +1,38 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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
+ *
+ *     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 org.apache.hadoop.hbase.http.gson;
+
+import java.lang.reflect.Type;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.apache.hbase.thirdparty.com.google.gson.JsonElement;
+import org.apache.hbase.thirdparty.com.google.gson.JsonPrimitive;
+import org.apache.hbase.thirdparty.com.google.gson.JsonSerializationContext;
+import org.apache.hbase.thirdparty.com.google.gson.JsonSerializer;
+
+/**
+ * Serialize a {@code byte[]} using {@link Bytes#toString()}.
+ */
+@InterfaceAudience.Private
+public final class ByteArraySerializer implements JsonSerializer<byte[]> {
+
+  @Override
+  public JsonElement serialize(byte[] src, Type typeOfSrc, JsonSerializationContext context) {
+    return new JsonPrimitive(Bytes.toString(src));
+  }
+}

hbase-http/src/main/java/org/apache/hadoop/hbase/http/gson/GsonMessageBodyWriter.java

@@ -0,0 +1,99 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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
+ *
+ *     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 org.apache.hadoop.hbase.http.gson;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Type;
+import java.nio.charset.Charset;
+import java.nio.charset.IllegalCharsetNameException;
+import java.nio.charset.StandardCharsets;
+import java.nio.charset.UnsupportedCharsetException;
+import java.util.Optional;
+import javax.inject.Inject;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.apache.hbase.thirdparty.com.google.gson.Gson;
+import org.apache.hbase.thirdparty.javax.ws.rs.Produces;
+import org.apache.hbase.thirdparty.javax.ws.rs.WebApplicationException;
+import org.apache.hbase.thirdparty.javax.ws.rs.core.MediaType;
+import org.apache.hbase.thirdparty.javax.ws.rs.core.MultivaluedMap;
+import org.apache.hbase.thirdparty.javax.ws.rs.ext.MessageBodyWriter;
+
+/**
+ * Implements JSON serialization via {@link Gson} for JAX-RS.
+ */
+@InterfaceAudience.Private
+@Produces(MediaType.APPLICATION_JSON)
+public final class GsonMessageBodyWriter<T> implements MessageBodyWriter<T> {
+  private static final Logger logger = LoggerFactory.getLogger(GsonMessageBodyWriter.class);
+
+  private final Gson gson;
+
+  @Inject
+  public GsonMessageBodyWriter(Gson gson) {
+    this.gson = gson;
+  }
+
+  @Override
+  public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations,
+    MediaType mediaType) {
+    return mediaType == null || MediaType.APPLICATION_JSON_TYPE.isCompatible(mediaType);
+  }
+
+  @Override
+  public void writeTo(
+    T t,
+    Class<?> type,
+    Type genericType,
+    Annotation[] annotations,
+    MediaType mediaType,
+    MultivaluedMap<String, Object> httpHeaders,
+    OutputStream entityStream
+  ) throws IOException, WebApplicationException {
+    final Charset outputCharset = requestedCharset(mediaType);
+    try (Writer writer = new OutputStreamWriter(entityStream, outputCharset)) {
+      gson.toJson(t, writer);
+    }
+  }
+
+  private static Charset requestedCharset(MediaType mediaType) {
+    return Optional.ofNullable(mediaType)
+      .map(MediaType::getParameters)
+      .map(params -> params.get("charset"))
+      .map(c -> {
+        try {
+          return Charset.forName(c);
+        } catch (IllegalCharsetNameException e) {
+          logger.debug("Client requested illegal Charset '{}'", c);
+          return null;
+        } catch (UnsupportedCharsetException e) {
+          logger.debug("Client requested unsupported Charset '{}'", c);
+          return null;
+        } catch (Exception e) {
+          logger.debug("Error while resolving Charset '{}'", c, e);
+          return null;
+        }
+      })
+      .orElse(StandardCharsets.UTF_8);
+  }
+}

hbase-http/src/main/java/org/apache/hadoop/hbase/http/jersey/ResponseEntityMapper.java

@@ -0,0 +1,53 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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
+ *
+ *     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 org.apache.hadoop.hbase.http.jersey;
+
+import java.io.IOException;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.apache.hbase.thirdparty.com.google.common.collect.ImmutableMap;
+import org.apache.hbase.thirdparty.javax.ws.rs.container.ContainerRequestContext;
+import org.apache.hbase.thirdparty.javax.ws.rs.container.ContainerResponseContext;
+import org.apache.hbase.thirdparty.javax.ws.rs.container.ContainerResponseFilter;
+import org.apache.hbase.thirdparty.javax.ws.rs.core.Response.Status;
+
+/**
+ * Generate a uniform response wrapper around the Entity returned from the resource.
+ * @see <a href="https://jsonapi.org/format/#document-top-level">JSON API Document Structure</a>
+ * @see <a href="https://jsonapi.org/format/#error-objects">JSON API Error Objects</a>
+ */
+@InterfaceAudience.Private
+public class ResponseEntityMapper implements ContainerResponseFilter {
+
+  @Override
+  public void filter(
+    ContainerRequestContext requestContext,
+    ContainerResponseContext responseContext
+  ) throws IOException {
+    /*
+     * Follows very loosely the top-level document specification described in by JSON API. Only
+     * handles 200 response codes; leaves room for errors and other response types.
+     */
+
+    final int statusCode = responseContext.getStatus();
+    if (Status.OK.getStatusCode() != statusCode) {
+      return;
+    }
+
+    responseContext.setEntity(ImmutableMap.of("data", responseContext.getEntity()));
+  }
+}

hbase-http/src/main/java/org/apache/hadoop/hbase/http/jersey/SupplierFactoryAdapter.java

@@ -0,0 +1,42 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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
+ *
+ *     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 org.apache.hadoop.hbase.http.jersey;
+
+import java.util.function.Supplier;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.apache.hbase.thirdparty.org.glassfish.hk2.api.Factory;
+
+/**
+ * Use a {@link Supplier} of type {@code T} as a {@link Factory} that provides instances of
+ * {@code T}. Modeled after Jersey's internal implementation.
+ */
+@InterfaceAudience.Private
+public class SupplierFactoryAdapter<T> implements Factory<T> {
+
+  private final Supplier<T> supplier;
+
+  public SupplierFactoryAdapter(Supplier<T> supplier) {
+    this.supplier = supplier;
+  }
+
+  @Override public T provide() {
+    return supplier.get();
+  }
+
+  @Override public void dispose(T instance) { }
+}