[GitHub] [hbase] Apache9 commented on a diff in pull request #4691: HBASE-20904 Prometheus /metrics http endpoint for monitoring

[GitBox <gi...@apache.org>]

Apache9 commented on code in PR #4691:
URL: https://github.com/apache/hbase/pull/4691#discussion_r942426722


##########
hbase-http/src/main/java/org/apache/hadoop/hbase/http/prometheus/PrometheusHadoop2Servlet.java:
##########
@@ -0,0 +1,86 @@
+/*
+ * 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.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 com.google.errorprone.annotations.RestrictedApi;
+import org.apache.commons.lang3.StringUtils;
+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;
+import org.apache.yetus.audience.InterfaceAudience;
+
+@InterfaceAudience.Private
+public class PrometheusHadoop2Servlet 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());
+  }
+
+  static String toPrometheusName(String metricRecordName, String metricName) {
+    String baseName = metricRecordName + StringUtils.capitalize(metricName);
+    String[] parts = SPLIT_PATTERN.split(baseName);
+    return String
+      .join("_", parts)
+      .toLowerCase();
+  }
+
+  @RestrictedApi(explanation = "Should only be called in tests", link = "",
+    allowedOnPath = ".*/src/test/.*")
+  void writeMetrics(Writer writer) 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) {

Review Comment:
   We do not want to rely on prometheus simpleclient to do this?



##########
hbase-http/src/main/java/org/apache/hadoop/hbase/http/prometheus/PrometheusHadoop2Servlet.java:
##########
@@ -0,0 +1,86 @@
+/*
+ * 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.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 com.google.errorprone.annotations.RestrictedApi;
+import org.apache.commons.lang3.StringUtils;
+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;
+import org.apache.yetus.audience.InterfaceAudience;
+
+@InterfaceAudience.Private
+public class PrometheusHadoop2Servlet extends HttpServlet {

Review Comment:
   Why name it hadoop2, not hadoop?



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