Silence hadoop-azure errors logged for virtual directories listings, …

graylog2-server/src/main/resources/log4j2.xml

@@ -37,6 +37,12 @@
         <Logger name="com.azure.core.amqp.implementation.MessageFlux" level="off"/>
         <!-- Silence Apache Hadoop/Avro log chatter -->
         <Logger name="org.apache.hadoop" level="warn"/>
+        <!-- hadoop-azure FNS blob listings return virtual directories without a Last-Modified value,
+             which this class logs as an unparseable "null" date on every listing (HADOOP-19207 area).
+             Genuinely malformed dates still get logged. -->
+        <Logger name="org.apache.hadoop.fs.azurebfs.utils.DateTimeUtils" level="error">
+            <RegexFilter regex="Failed to parse the date null" onMatch="DENY" onMismatch="ACCEPT"/>
+        </Logger>
         <Logger name="org.apache.parquet.hadoop.InternalParquetRecordReader" level="warn"/>
         <Logger name="org.apache.avro.Schema" level="error"/>
         <!-- Silence Selenium log chatter -->

graylog2-server/src/test/java/org/graylog2/log4j/ProductionLogConfigTest.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2020 Graylog, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the Server Side Public License, version 1,
+ * as published by MongoDB, Inc.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * Server Side Public License for more details.
+ *
+ * You should have received a copy of the Server Side Public License
+ * along with this program. If not, see
+ * <http://www.mongodb.com/licensing/server-side-public-license>.
+ */
+package org.graylog2.log4j;
+
+import org.apache.logging.log4j.Level;
+import org.apache.logging.log4j.core.LogEvent;
+import org.apache.logging.log4j.core.Logger;
+import org.apache.logging.log4j.core.LoggerContext;
+import org.apache.logging.log4j.core.appender.AbstractAppender;
+import org.apache.logging.log4j.core.config.ConfigurationSource;
+import org.apache.logging.log4j.core.config.LoggerConfig;
+import org.apache.logging.log4j.core.config.Property;
+import org.apache.logging.log4j.core.config.xml.XmlConfiguration;
+import org.junit.jupiter.api.Test;
+
+import java.io.InputStream;
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests logger configurations in the production {@code log4j2.xml}. The config is loaded into a private
+ * {@link LoggerContext} because the global test context uses {@code log4j2-test.xml}.
+ */
+public class ProductionLogConfigTest {
+    private static final String ABFS_DATE_LOGGER = "org.apache.hadoop.fs.azurebfs.utils.DateTimeUtils";
+
+    @Test
+    void abfsNullDateSpamIsSuppressedButOtherParseFailuresAreLogged() throws Exception {
+        try (final InputStream configStream = getClass().getResourceAsStream("/log4j2.xml")) {
+            final LoggerContext context = new LoggerContext("production-log4j2-xml");
+            context.start(new XmlConfiguration(context, new ConfigurationSource(configStream)));
+            try {
+                final LoggerConfig loggerConfig = context.getConfiguration().getLoggerConfig(ABFS_DATE_LOGGER);
+                assertThat(loggerConfig.getName()).isEqualTo(ABFS_DATE_LOGGER);
+
+                final List<String> messages = new CopyOnWriteArrayList<>();
+                final AbstractAppender capture =
+                        new AbstractAppender("capture", null, null, true, Property.EMPTY_ARRAY) {
+                            @Override
+                            public void append(final LogEvent event) {
+                                messages.add(event.getMessage().getFormattedMessage());
+                            }
+                        };
+                capture.start();
+                loggerConfig.addAppender(capture, Level.ALL, null);
+
+                final Logger logger = context.getLogger(ABFS_DATE_LOGGER);
+                // hadoop-azure FNS blob listings log this for virtual directories, which have no Last-Modified
+                // value. See the comment on the logger entry in log4j2.xml.
+                logger.error("Failed to parse the date {}", "null");
+                // A genuinely malformed date must remain visible.
+                logger.error("Failed to parse the date {}", "Tue, 99 Foo 2026 25:61:61 GMT");
+
+                assertThat(messages).containsExactly("Failed to parse the date Tue, 99 Foo 2026 25:61:61 GMT");
+            } finally {
+                context.stop();
+            }
+        }
+    }
+}