Create a logstash tcp socket appender factory

pom.xml

@@ -152,6 +152,11 @@
             <version>5.7.1</version>
             <type>pom</type>
         </dependency>
+        <dependency>
+            <groupId>net.logstash.logback</groupId>
+            <artifactId>logstash-logback-encoder</artifactId>
+            <version>6.6</version>
+        </dependency>
     </dependencies>
 
     <build>

service/src/main/java/org/whispersystems/textsecuregcm/metrics/LogstashTcpSocketAppenderFactory.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2021 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.metrics;
+
+import ch.qos.logback.classic.LoggerContext;
+import ch.qos.logback.classic.PatternLayout;
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.core.Appender;
+import ch.qos.logback.core.encoder.LayoutWrappingEncoder;
+import ch.qos.logback.core.net.ssl.SSLConfiguration;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonTypeName;
+import io.dropwizard.logging.AbstractAppenderFactory;
+import io.dropwizard.logging.async.AsyncAppenderFactory;
+import io.dropwizard.logging.filter.LevelFilterFactory;
+import io.dropwizard.logging.layout.LayoutFactory;
+import java.time.Duration;
+import javax.validation.constraints.NotEmpty;
+import net.logstash.logback.appender.LogstashTcpSocketAppender;
+import net.logstash.logback.encoder.LogstashEncoder;
+
+@JsonTypeName("logstashtcpsocket")
+public class LogstashTcpSocketAppenderFactory extends AbstractAppenderFactory<ILoggingEvent> {
+
+  @NotEmpty
+  private String destination;
+
+  private Duration keepAlive = Duration.ofSeconds(20);
+
+  @NotEmpty
+  private String apiKey;
+
+  @JsonProperty
+  public String getDestination() {
+    return destination;
+  }
+
+  @JsonProperty
+  public Duration getKeepAlive() {
+    return keepAlive;
+  }
+
+  @JsonProperty
+  public String getApiKey() {
+    return apiKey;
+  }
+
+  @Override
+  public Appender<ILoggingEvent> build(
+      final LoggerContext context,
+      final String applicationName,
+      final LayoutFactory<ILoggingEvent> layoutFactory,
+      final LevelFilterFactory<ILoggingEvent> levelFilterFactory,
+      final AsyncAppenderFactory<ILoggingEvent> asyncAppenderFactory) {
+
+    final SSLConfiguration sslConfiguration = new SSLConfiguration();
+    final LogstashTcpSocketAppender appender = new LogstashTcpSocketAppender();
+    appender.setName("logstashtcpsocket-appender");
+    appender.setContext(context);
+    appender.setSsl(sslConfiguration);
+    appender.addDestination(destination);
+    appender.setKeepAliveDuration(new ch.qos.logback.core.util.Duration(keepAlive.toMillis()));
+
+    final LogstashEncoder encoder = new LogstashEncoder();
+    final LayoutWrappingEncoder<ILoggingEvent> prefix = new LayoutWrappingEncoder<>();
+    final PatternLayout layout = new PatternLayout();
+    layout.setPattern(String.format("%s ", apiKey));
+    prefix.setLayout(layout);
+    encoder.setPrefix(prefix);
+    appender.setEncoder(encoder);
+
+    appender.addFilter(levelFilterFactory.build(threshold));
+    getFilterFactories().forEach(f -> appender.addFilter(f.build()));
+    appender.start();
+
+    return wrapAsync(appender, asyncAppenderFactory);
+  }
+}

service/src/main/resources/META-INF/services/io.dropwizard.logging.AppenderFactory

@@ -1 +1 @@
-org.whispersystems.textsecuregcm.metrics.LoggingNetworkAppenderFactory
+org.whispersystems.textsecuregcm.metrics.LogstashTcpSocketAppenderFactory