PHOENIX-6879 Prometheus endpoint implementation

phoenix-queryserver/src/main/java/org/apache/hadoop/metrics2/impl/MetricsExportHelper.java

@@ -0,0 +1,39 @@
+/*
+ * 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.metrics2.impl;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import org.apache.hadoop.metrics2.MetricsRecord;
+import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem;
+
+public final class MetricsExportHelper {
+    private MetricsExportHelper() {
+    }
+
+    public static Collection<MetricsRecord> export() {
+        MetricsSystemImpl instance = (MetricsSystemImpl) DefaultMetricsSystem.instance();
+        MetricsBuffer metricsBuffer = instance.sampleMetrics();
+        List<MetricsRecord> metrics = new ArrayList<>();
+        for (MetricsBuffer.Entry entry : metricsBuffer) {
+            entry.records().forEach(metrics::add);
+        }
+        return metrics;
+    }
+}

phoenix-queryserver/src/main/java/org/apache/phoenix/queryserver/QueryServerOptions.java

@@ -38,6 +38,7 @@ public class QueryServerOptions {
     public static final String DEFAULT_QUERY_SERVER_REMOTEUSEREXTRACTOR_PARAM = "doAs";
     public static final boolean DEFAULT_QUERY_SERVER_DISABLE_KERBEROS_LOGIN = false;
     public static final boolean DEFAULT_QUERY_SERVER_JMXJSONENDPOINT_DISABLED = false;
+    public static final boolean DEFAULT_QUERY_SERVER_PROMETHEUS_ENDPOINT_ENABLED = true;
 
     public static final boolean DEFAULT_QUERY_SERVER_TLS_ENABLED = false;
     //We default to empty *store password

phoenix-queryserver/src/main/java/org/apache/phoenix/queryserver/QueryServerProperties.java

@@ -75,6 +75,9 @@ public class QueryServerProperties {
     public static final String QUERY_SERVER_JMX_JSON_ENDPOINT_DISABLED =
             "phoenix.queryserver.jmxjsonendpoint.disabled";
 
+    public static final String QUERY_SERVER_PROMETHEUS_ENDPOINT_ENABLED =
+            "phoenix.queryserver.prometheusendpoint.enabled";
+
     // keys for load balancer
     public static final String PHOENIX_QUERY_SERVER_LOADBALANCER_ENABLED =
             "phoenix.queryserver.loadbalancer.enabled";

phoenix-queryserver/src/main/java/org/apache/phoenix/queryserver/server/ServerCustomizersFactory.java

@@ -29,6 +29,7 @@
 import org.apache.phoenix.queryserver.QueryServerProperties;
 import org.apache.phoenix.queryserver.server.customizers.HostedClientJarsServerCustomizer;
 import org.apache.phoenix.queryserver.server.customizers.JMXJsonEndpointServerCustomizer;
+import org.apache.phoenix.queryserver.server.customizers.prometheus.PrometheusEndpointServerCustomizer;
 import org.eclipse.jetty.server.Server;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -76,6 +77,12 @@ public List<ServerCustomizer<Server>> createServerCustomizers(Configuration conf
                 QueryServerOptions.DEFAULT_QUERY_SERVER_JMXJSONENDPOINT_DISABLED)) {
                 customizers.add(new JMXJsonEndpointServerCustomizer());
             }
+
+            if (conf.getBoolean(QueryServerProperties.QUERY_SERVER_PROMETHEUS_ENDPOINT_ENABLED,
+                    QueryServerOptions.DEFAULT_QUERY_SERVER_PROMETHEUS_ENDPOINT_ENABLED)) {
+                customizers.add(new PrometheusEndpointServerCustomizer());
+            }
+
             return Collections.unmodifiableList(customizers);
         }
     }

phoenix-queryserver/src/main/java/org/apache/phoenix/queryserver/server/customizers/prometheus/PrometheusEndpointServerCustomizer.java

@@ -0,0 +1,57 @@
+/*
+ * 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.phoenix.queryserver.server.customizers.prometheus;
+
+import org.apache.calcite.avatica.server.ServerCustomizer;
+import org.eclipse.jetty.server.Handler;
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.server.handler.HandlerList;
+import org.eclipse.jetty.servlet.ServletContextHandler;
+import org.eclipse.jetty.servlet.ServletHolder;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.servlet.Servlet;
+import java.util.Arrays;
+
+public class PrometheusEndpointServerCustomizer implements ServerCustomizer<Server> {
+    private static final Logger LOG = LoggerFactory.getLogger(PrometheusEndpointServerCustomizer.class);
+
+    @Override
+    public void customize(Server server) {
+        Handler[] handlers = server.getHandlers();
+        if (handlers.length != 1) {
+            LOG.warn("Observed handlers on server {}", Arrays.toString(handlers));
+            throw new IllegalStateException("Expected to find one handler");
+        }
+        HandlerList list = (HandlerList) handlers[0];
+
+        ServletContextHandler ctx = new ServletContextHandler();
+        ctx.setContextPath("/prometheus");
+
+        Servlet servlet = new PrometheusHadoopServlet();
+        ServletHolder holder = new ServletHolder(servlet);
+        ctx.addServlet(holder, "/");
+
+        Handler[] realHandlers = list.getChildHandlers();
+        Handler[] newHandlers = new Handler[realHandlers.length + 1];
+        newHandlers[0] = ctx;
+        System.arraycopy(realHandlers, 0, newHandlers, 1, realHandlers.length);
+        server.setHandler(new HandlerList(newHandlers));
+    }
+}

phoenix-queryserver/src/main/java/org/apache/phoenix/queryserver/server/customizers/prometheus/PrometheusHadoopServlet.java

@@ -0,0 +1,83 @@
+/*
+ * 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.phoenix.queryserver.server.customizers.prometheus;
+
+import java.io.IOException;
+import java.io.Writer;
+import java.util.Collection;
+import java.util.regex.Pattern;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import org.apache.hadoop.metrics2.AbstractMetric;
+import org.apache.hadoop.metrics2.MetricType;
+import org.apache.hadoop.metrics2.MetricsRecord;
+import org.apache.hadoop.metrics2.MetricsTag;
+import org.apache.hadoop.metrics2.impl.MetricsExportHelper;
+
+public class PrometheusHadoopServlet extends HttpServlet {
+    private static final Pattern SPLIT_PATTERN =
+            Pattern.compile("(?<=[a-z])(?=[A-Z])|(?<=[A-Z])(?=([A-Z][a-z]))|\\W|(_)+");
+
+    @Override
+    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
+        writeMetrics(resp.getWriter(), "true".equals(req.getParameter("description")),
+                req.getParameter("qry"));
+    }
+
+    String toPrometheusName(String metricRecordName, String metricName) {
+        String baseName = metricRecordName + metricName.substring(0,1).toUpperCase() + metricName.substring(1);
+        String[] parts = SPLIT_PATTERN.split(baseName);
+        return String.join("_", parts).toLowerCase();
+    }
+
+    void writeMetrics(Writer writer, boolean descriptionEnabled, String queryParam)
+            throws IOException {
+        Collection<MetricsRecord> metricRecords = MetricsExportHelper.export();
+        for (MetricsRecord metricsRecord : metricRecords) {
+            for (AbstractMetric metrics : metricsRecord.metrics()) {
+                if (metrics.type() == MetricType.COUNTER || metrics.type() == MetricType.GAUGE) {
+
+                    String key = toPrometheusName(metricsRecord.name(), metrics.name());
+
+                    if (queryParam == null || key.contains(queryParam)) {
+
+                        if (descriptionEnabled) {
+                            String description = metrics.description();
+                            if (!description.isEmpty()) writer.append("# HELP ").append(description).append('\n');
+                        }
+
+                        writer.append("# TYPE ").append(key).append(" ")
+                                .append(metrics.type().toString().toLowerCase()).append('\n').append(key).append("{");
+
+                        /* add tags */
+                        String sep = "";
+                        for (MetricsTag tag : metricsRecord.tags()) {
+                            String tagName = tag.name().toLowerCase();
+                            writer.append(sep).append(tagName).append("=\"").append(tag.value()).append("\"");
+                            sep = ",";
+                        }
+                        writer.append("} ");
+                        writer.append(metrics.value().toString()).append('\n');
+                    }
+                }
+            }
+        }
+        writer.flush();
+    }
+}

phoenix-queryserver/src/test/java/org/apache/phoenix/queryserver/server/ServerCustomizersTest.java

@@ -26,6 +26,7 @@
 import org.apache.hadoop.conf.Configuration;
 import org.apache.phoenix.query.QueryServices;
 import org.apache.phoenix.queryserver.QueryServerProperties;
+import org.apache.phoenix.queryserver.server.customizers.prometheus.PrometheusEndpointServerCustomizer;
 import org.apache.phoenix.util.InstanceResolver;
 import org.eclipse.jetty.server.Server;
 import org.junit.After;
@@ -51,7 +52,7 @@ public void testDefaultFactory() {
         // the default factory creates an empty list of server customizers
         List<ServerCustomizer<Server>> customizers =
                 queryServer.createServerCustomizers(new Configuration(), avaticaServerConfiguration);
-        Assert.assertEquals(1, customizers.size());
+        Assert.assertEquals(2, customizers.size());
     }
 
     @Test
@@ -77,4 +78,14 @@ public List<ServerCustomizer<Server>> createServerCustomizers(Configuration conf
         List<ServerCustomizer<Server>> actual = queryServer.createServerCustomizers(conf, avaticaServerConfiguration);
         Assert.assertEquals("Customizers are different", expected, actual);
     }
+
+    @Test
+    public void testPrometheusServletCustomizer() {
+        QueryServer queryServer = new QueryServer();
+
+        List<ServerCustomizer<Server>> customizers =
+                queryServer.createServerCustomizers(new Configuration(), null);
+
+        Assert.assertTrue(customizers.get(1) instanceof PrometheusEndpointServerCustomizer);
+    }
 }

phoenix-queryserver/src/test/java/org/apache/phoenix/queryserver/server/customizers/prometheus/PrometheusHadoopServletTest.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.phoenix.queryserver.server.customizers.prometheus;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import javax.servlet.http.HttpServletResponse;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class PrometheusHadoopServletTest {
+    private final PrometheusHadoopServlet servlet = new PrometheusHadoopServlet();
+
+    //NullPointerException is expected because the MetricExportHelper doesn't have any metrics to export
+    @Test(expected = NullPointerException.class)
+    public void testPrometheusServletMetricsWriter() throws IOException {
+        HttpServletResponse response = mock(HttpServletResponse.class);
+
+        PrintWriter writer = new PrintWriter(System.out);
+        when(response.getWriter()).thenReturn(writer);
+
+        servlet.writeMetrics(response.getWriter(),false,"");
+    }
+
+    @Test
+    public void testPrometheusNameConversion() {
+        String metricRecordName = "TestMetricRecord";
+        String metricName = "TestMetricName";
+
+        Assert.assertEquals("test_metric_record_test_metric_name",servlet.toPrometheusName(metricRecordName,metricName));
+    }
+}
+