From ffdb0db6c6a5602ef8c6ba8d712353d1c475bfb4 Mon Sep 17 00:00:00 2001
From: Chris Eager <chris@signal.org>
Date: Mon, 22 Jan 2024 10:56:03 -0600
Subject: [PATCH] Migrate from `host` tag to `dd.internal.entity_id`

---
 .../textsecuregcm/metrics/MetricsUtil.java     |  2 --
 .../metrics/SignalDatadogReporterFactory.java  | 18 +++++++++++-------
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/service/src/main/java/org/whispersystems/textsecuregcm/metrics/MetricsUtil.java b/service/src/main/java/org/whispersystems/textsecuregcm/metrics/MetricsUtil.java
index 2a7ddbe5d..659d3cbcd 100644
--- a/service/src/main/java/org/whispersystems/textsecuregcm/metrics/MetricsUtil.java
+++ b/service/src/main/java/org/whispersystems/textsecuregcm/metrics/MetricsUtil.java
@@ -20,7 +20,6 @@ import org.whispersystems.textsecuregcm.WhisperServerConfiguration;
 import org.whispersystems.textsecuregcm.WhisperServerVersion;
 import org.whispersystems.textsecuregcm.push.PushLatencyManager;
 import org.whispersystems.textsecuregcm.util.Constants;
-import org.whispersystems.textsecuregcm.util.HostnameUtil;
 
 public class MetricsUtil {
 
@@ -52,7 +51,6 @@ public class MetricsUtil {
       dogstatsdMeterRegistry.config().commonTags(
           Tags.of(
               "service", "chat",
-              "host", HostnameUtil.getLocalHostname(),
               "version", WhisperServerVersion.getServerVersion(),
               "env", config.getDatadogConfiguration().getEnvironment()));
 
diff --git a/service/src/main/java/org/whispersystems/textsecuregcm/metrics/SignalDatadogReporterFactory.java b/service/src/main/java/org/whispersystems/textsecuregcm/metrics/SignalDatadogReporterFactory.java
index 3d6049096..fa610ea61 100644
--- a/service/src/main/java/org/whispersystems/textsecuregcm/metrics/SignalDatadogReporterFactory.java
+++ b/service/src/main/java/org/whispersystems/textsecuregcm/metrics/SignalDatadogReporterFactory.java
@@ -21,6 +21,7 @@ import java.util.List;
 import javax.validation.Valid;
 import javax.validation.constraints.Min;
 import javax.validation.constraints.NotNull;
+import org.apache.commons.lang3.StringUtils;
 import org.coursera.metrics.datadog.DatadogReporter;
 import org.coursera.metrics.datadog.DatadogReporter.Expansion;
 import org.coursera.metrics.datadog.DefaultMetricNameFormatterFactory;
@@ -28,7 +29,6 @@ import org.coursera.metrics.datadog.DynamicTagsCallbackFactory;
 import org.coursera.metrics.datadog.MetricNameFormatterFactory;
 import org.coursera.metrics.datadog.transport.UdpTransport;
 import org.whispersystems.textsecuregcm.WhisperServerVersion;
-import org.whispersystems.textsecuregcm.util.HostnameUtil;
 
 @JsonTypeName("signal-datadog")
 public class SignalDatadogReporterFactory extends BaseReporterFactory {
@@ -66,23 +66,27 @@ public class SignalDatadogReporterFactory extends BaseReporterFactory {
   );
 
   public ScheduledReporter build(final MetricRegistry registry) {
-    final List<String> tagsWithVersion;
+    final List<String> combinedTags;
 
     {
       final String versionTag = "version:" + WhisperServerVersion.getServerVersion();
 
       if (tags != null) {
-        tagsWithVersion = new ArrayList<>(tags);
-        tagsWithVersion.add(versionTag);
+        combinedTags = new ArrayList<>(tags);
+        combinedTags.add(versionTag);
       } else {
-        tagsWithVersion = List.of(versionTag);
+        combinedTags = new ArrayList<>((List.of(versionTag)));
       }
     }
 
+    final String entityId = StringUtils.stripToNull(System.getenv("DD_ENTITY_ID"));
+    if (entityId != null) {
+      combinedTags.add("dd.internal.entity_id:" + entityId);
+    }
+
     return DatadogReporter.forRegistry(registry)
         .withTransport(udpTransportConfig.udpTransport())
-        .withHost(HostnameUtil.getLocalHostname())
-        .withTags(tagsWithVersion)
+        .withTags(combinedTags)
         .withPrefix(prefix)
         .withExpansions(EXPANSIONS)
         .withMetricNameFormatter(metricNameFormatter.build())