Backpropagate container tags hash coming from the info endpoint

communication/src/main/java/datadog/communication/ddagent/DDAgentFeaturesDiscovery.java

@@ -1,5 +1,7 @@
 package datadog.communication.ddagent;
 
+import static datadog.communication.http.OkHttpUtils.DATADOG_CONTAINER_ID;
+import static datadog.communication.http.OkHttpUtils.DATADOG_CONTAINER_TAGS_HASH;
 import static datadog.communication.serialization.msgpack.MsgPackWriter.FIXARRAY;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.singletonList;
@@ -8,6 +10,7 @@
 import com.squareup.moshi.JsonAdapter;
 import com.squareup.moshi.Moshi;
 import com.squareup.moshi.Types;
+import datadog.common.container.ContainerInfo;
 import datadog.communication.http.OkHttpUtils;
 import datadog.communication.monitor.DDAgentStatsDClientManager;
 import datadog.communication.monitor.Monitoring;
@@ -157,11 +160,15 @@ private void doDiscovery() {
     // 3. fallback if the endpoint couldn't be found or the response couldn't be parsed
     try (Recording recording = discoveryTimer.start()) {
       boolean fallback = true;
-      try (Response response =
-          client
-              .newCall(new Request.Builder().url(agentBaseUrl.resolve("info").url()).build())
-              .execute()) {
+      final Request.Builder requestBuilder =
+          new Request.Builder().url(agentBaseUrl.resolve("info").url());
+      final String containerId = ContainerInfo.get().getContainerId();
+      if (containerId != null) {
+        requestBuilder.header(DATADOG_CONTAINER_ID, containerId);
+      }
+      try (Response response = client.newCall(requestBuilder.build()).execute()) {
         if (response.isSuccessful()) {
+          processInfoResponseHeaders(response);
           fallback = !processInfoResponse(response.body().string());
         }
       } catch (Throwable error) {
@@ -222,6 +229,10 @@ private String probeTracesEndpoint(String[] endpoints) {
     return V3_ENDPOINT;
   }
 
+  private void processInfoResponseHeaders(Response response) {
+    ContainerInfo.get().setContainerTagsHash(response.header(DATADOG_CONTAINER_TAGS_HASH));
+  }
+
   @SuppressWarnings("unchecked")
   private boolean processInfoResponse(String response) {
     try {

communication/src/main/java/datadog/communication/http/OkHttpUtils.java

@@ -43,8 +43,9 @@ public final class OkHttpUtils {
   private static final String DATADOG_META_LANG_INTERPRETER = "Datadog-Meta-Lang-Interpreter";
   private static final String DATADOG_META_LANG_INTERPRETER_VENDOR =
       "Datadog-Meta-Lang-Interpreter-Vendor";
-  private static final String DATADOG_CONTAINER_ID = "Datadog-Container-ID";
+  public static final String DATADOG_CONTAINER_ID = "Datadog-Container-ID";
   private static final String DATADOG_ENTITY_ID = "Datadog-Entity-ID";
+  public static final String DATADOG_CONTAINER_TAGS_HASH = "Datadog-Container-Tags-Hash";
 
   private static final String DD_API_KEY = "DD-API-KEY";
 

communication/src/test/groovy/datadog/communication/ddagent/DDAgentFeaturesDiscoveryTest.groovy

@@ -1,9 +1,11 @@
 package datadog.communication.ddagent
 
+import datadog.common.container.ContainerInfo
 import datadog.communication.monitor.Monitoring
 import datadog.trace.test.util.DDSpecification
 import datadog.trace.util.Strings
 import okhttp3.Call
+import okhttp3.Headers
 import okhttp3.HttpUrl
 import okhttp3.MediaType
 import okhttp3.OkHttpClient
@@ -19,6 +21,8 @@ import java.nio.file.Paths
 import static datadog.communication.ddagent.DDAgentFeaturesDiscovery.V01_DATASTREAMS_ENDPOINT
 import static datadog.communication.ddagent.DDAgentFeaturesDiscovery.V6_METRICS_ENDPOINT
 import static datadog.communication.ddagent.DDAgentFeaturesDiscovery.V7_CONFIG_ENDPOINT
+import static datadog.communication.http.OkHttpUtils.DATADOG_CONTAINER_ID
+import static datadog.communication.http.OkHttpUtils.DATADOG_CONTAINER_TAGS_HASH
 
 class DDAgentFeaturesDiscoveryTest extends DDSpecification {
 
@@ -466,13 +470,37 @@ class DDAgentFeaturesDiscoveryTest extends DDSpecification {
       )
   }
 
-  def infoResponse(Request request, String json) {
+  def "should send container id as header on the info request and parse the hash in the response"() {
+    setup:
+    OkHttpClient client = Mock(OkHttpClient)
+    DDAgentFeaturesDiscovery features = new DDAgentFeaturesDiscovery(client, monitoring, agentUrl, true, true)
+    def oldContainerId = ContainerInfo.get().getContainerId()
+    def oldContainerTagsHash = ContainerInfo.get().getContainerTagsHash()
+    ContainerInfo.get().setContainerId("test")
+
+    when: "/info requested"
+    features.discover()
+
+    then:
+    1 * client.newCall(_) >> { Request request ->
+      assert request.header(DATADOG_CONTAINER_ID) == "test"
+      infoResponse(request, INFO_RESPONSE, Headers.of(DATADOG_CONTAINER_TAGS_HASH, "test-hash"))
+    }
+    and:
+    assert ContainerInfo.get().getContainerTagsHash() == "test-hash"
+    cleanup:
+    ContainerInfo.get().setContainerId(oldContainerId)
+    ContainerInfo.get().setContainerTagsHash(oldContainerTagsHash)
+  }
+
+  def infoResponse(Request request, String json, Headers headers = new Headers.Builder().build()) {
     return Mock(Call) {
       it.execute() >> new Response.Builder()
         .code(200)
         .request(request)
         .protocol(Protocol.HTTP_1_1)
         .message("")
+        .headers(headers)
         .body(ResponseBody.create(MediaType.get("application/json"), json))
         .build()
     }

utils/container-utils/src/main/java/datadog/common/container/ContainerInfo.java

@@ -54,6 +54,7 @@ public class ContainerInfo {
   private static final String ENTITY_ID;
 
   public String containerId;
+  public String containerTagsHash;
   public String podId;
   public List<CGroupInfo> cGroups = new ArrayList<>();
 
@@ -65,6 +66,14 @@ public void setContainerId(String containerId) {
     this.containerId = containerId;
   }
 
+  public String getContainerTagsHash() {
+    return containerTagsHash;
+  }
+
+  public void setContainerTagsHash(String containerTagsHash) {
+    this.containerTagsHash = containerTagsHash;
+  }
+
   public String getPodId() {
     return podId;
   }