Add custom endpoint for agentless feature flags

Author: leoromanovsky

dd-trace-api/src/main/java/datadog/trace/api/config/FeatureFlaggingConfig.java

@@ -6,6 +6,8 @@ public class FeatureFlaggingConfig {
 
   public static final String FEATURE_FLAGS_CONFIGURATION_SOURCE =
       "feature.flags.configuration.source";
+  public static final String FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_BASE_URL =
+      "feature.flags.configuration.source.agentless.base.url";
   public static final String FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_POLL_INTERVAL_SECONDS =
       "feature.flags.configuration.source.agentless.poll.interval.seconds";
   public static final String FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_REQUEST_TIMEOUT_SECONDS =

internal-api/src/main/java/datadog/trace/api/Config.java

@@ -365,6 +365,7 @@
 import static datadog.trace.api.config.DebuggerConfig.THIRD_PARTY_INCLUDES;
 import static datadog.trace.api.config.DebuggerConfig.THIRD_PARTY_SHADING_IDENTIFIERS;
 import static datadog.trace.api.config.FeatureFlaggingConfig.FEATURE_FLAGS_CONFIGURATION_SOURCE;
+import static datadog.trace.api.config.FeatureFlaggingConfig.FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_BASE_URL;
 import static datadog.trace.api.config.FeatureFlaggingConfig.FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_POLL_INTERVAL_SECONDS;
 import static datadog.trace.api.config.FeatureFlaggingConfig.FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_REQUEST_TIMEOUT_SECONDS;
 import static datadog.trace.api.config.GeneralConfig.AGENTLESS_LOG_SUBMISSION_LEVEL;
@@ -1220,6 +1221,7 @@ public static String getHostName() {
   private final int remoteConfigMaxExtraServices;
 
   private final String featureFlaggingConfigurationSource;
+  private final String featureFlaggingConfigurationSourceAgentlessBaseUrl;
   private final double featureFlaggingConfigurationSourcePollIntervalSeconds;
   private final double featureFlaggingConfigurationSourceRequestTimeoutSeconds;
 
@@ -2849,6 +2851,9 @@ PROFILING_DATADOG_PROFILER_ENABLED, isDatadogProfilerSafeInCurrentEnvironment())
         normalizeFeatureFlaggingConfigurationSource(
             configProvider.getString(
                 FEATURE_FLAGS_CONFIGURATION_SOURCE, DEFAULT_FEATURE_FLAGGING_CONFIGURATION_SOURCE));
+    featureFlaggingConfigurationSourceAgentlessBaseUrl =
+        configProvider.getStringNotEmpty(
+            FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_BASE_URL, null);
     featureFlaggingConfigurationSourcePollIntervalSeconds =
         configProvider.getDouble(
             FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_POLL_INTERVAL_SECONDS,
@@ -4689,6 +4694,10 @@ public String getFeatureFlaggingConfigurationSource() {
     return featureFlaggingConfigurationSource;
   }
 
+  public String getFeatureFlaggingConfigurationSourceAgentlessBaseUrl() {
+    return featureFlaggingConfigurationSourceAgentlessBaseUrl;
+  }
+
   public double getFeatureFlaggingConfigurationSourcePollIntervalSeconds() {
     return featureFlaggingConfigurationSourcePollIntervalSeconds;
   }
@@ -6531,6 +6540,8 @@ public String toString() {
         + remoteConfigIntegrityCheckEnabled
         + ", featureFlaggingConfigurationSource="
         + featureFlaggingConfigurationSource
+        + ", featureFlaggingConfigurationSourceAgentlessBaseUrl="
+        + featureFlaggingConfigurationSourceAgentlessBaseUrl
         + ", featureFlaggingConfigurationSourcePollIntervalSeconds="
         + featureFlaggingConfigurationSourcePollIntervalSeconds
         + ", featureFlaggingConfigurationSourceRequestTimeoutSeconds="

metadata/supported-configurations.json

@@ -1505,6 +1505,14 @@
         "aliases": []
       }
     ],
+    "DD_FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_BASE_URL": [
+      {
+        "version": "A",
+        "type": "string",
+        "default": null,
+        "aliases": []
+      }
+    ],
     "DD_FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_POLL_INTERVAL_SECONDS": [
       {
         "version": "A",

products/feature-flagging/feature-flagging-api/README.md

@@ -86,6 +86,10 @@ OTEL_EXPORTER_OTLP_PROTOCOL=grpc
 
 - Java 11+
 - `DD_FEATURE_FLAGS_CONFIGURATION_SOURCE=agentless` uses the Datadog agentless
-  backend. `remote_config` uses the existing Agent Remote Configuration path.
-  `offline` is reserved for startup-provided UFC bytes; until those bytes are
-  implemented, no network source starts and evaluations use defaults.
+  backend. Set `DD_FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_BASE_URL` to a
+  different HTTP backend while keeping agentless delivery semantics. A bare
+  host uses the standard server-distribution path; a URL with a path is used as
+  the exact UFC endpoint. `remote_config` uses the existing Agent Remote
+  Configuration path. `offline` is reserved for startup-provided UFC bytes;
+  until those bytes are implemented, no network source starts and evaluations
+  use defaults.

products/feature-flagging/feature-flagging-lib/src/main/java/com/datadog/featureflag/AgentlessConfigurationSource.java

@@ -170,7 +170,11 @@ private void updateEtag(final String nextEtag) {
   }
 
   static HttpUrl endpoint(final Config config) {
-    final String endpoint = datadogApiServerDistributionEndpoint(config);
+    final String configuredBaseUrl = config.getFeatureFlaggingConfigurationSourceAgentlessBaseUrl();
+    final String endpoint =
+        configuredBaseUrl == null
+            ? datadogApiServerDistributionEndpoint(config)
+            : endpointFromConfiguredBaseUrl(configuredBaseUrl);
     final HttpUrl parsed = HttpUrl.parse(endpoint);
     if (parsed == null) {
       throw new IllegalArgumentException(
@@ -179,6 +183,22 @@ static HttpUrl endpoint(final Config config) {
     return parsed;
   }
 
+  private static String endpointFromConfiguredBaseUrl(final String configuredBaseUrl) {
+    final HttpUrl parsed = HttpUrl.parse(configuredBaseUrl.trim());
+    if (parsed == null) {
+      throw new IllegalArgumentException(
+          "Invalid Feature Flagging HTTP configuration source URL: " + configuredBaseUrl);
+    }
+    if ("/".equals(parsed.encodedPath()) || parsed.encodedPath().isEmpty()) {
+      return parsed
+          .newBuilder()
+          .addPathSegments(DATADOG_API_SERVER_DISTRIBUTION_PATH.substring(1))
+          .build()
+          .toString();
+    }
+    return parsed.toString();
+  }
+
   private static String datadogApiServerDistributionEndpoint(final Config config) {
     final StringBuilder endpoint =
         new StringBuilder("https://api.")

products/feature-flagging/feature-flagging-lib/src/test/java/com/datadog/featureflag/AgentlessConfigurationSourceTest.java

@@ -70,6 +70,41 @@ void derivesDatadogApiServerDistributionEndpointWithoutEnv() {
         AgentlessConfigurationSource.endpoint(config("datadoghq.com", null)).toString());
   }
 
+  @Test
+  void appendsServerDistributionPathToConfiguredAgentlessBaseUrl() {
+    final Config config = config();
+    lenient()
+        .when(config.getFeatureFlaggingConfigurationSourceAgentlessBaseUrl())
+        .thenReturn("http://mock-backend:8080");
+
+    assertEquals(
+        "http://mock-backend:8080/api/v2/feature-flagging/config/server-distribution",
+        AgentlessConfigurationSource.endpoint(config).toString());
+  }
+
+  @Test
+  void usesConfiguredAgentlessEndpointWithPathUnchanged() {
+    final Config config = config();
+    lenient()
+        .when(config.getFeatureFlaggingConfigurationSourceAgentlessBaseUrl())
+        .thenReturn("http://mock-backend:8080/custom/ufc?tenant=test");
+
+    assertEquals(
+        "http://mock-backend:8080/custom/ufc?tenant=test",
+        AgentlessConfigurationSource.endpoint(config).toString());
+  }
+
+  @Test
+  void rejectsInvalidConfiguredAgentlessBaseUrl() {
+    final Config config = config();
+    lenient()
+        .when(config.getFeatureFlaggingConfigurationSourceAgentlessBaseUrl())
+        .thenReturn("not a URL");
+
+    assertThrows(
+        IllegalArgumentException.class, () -> AgentlessConfigurationSource.endpoint(config));
+  }
+
   @Test
   void rejectsInvalidDatadogApiServerDistributionEndpoint() {
     assertThrows(
@@ -398,6 +433,7 @@ private static Config config(final String site, final String env) {
     lenient()
         .when(config.getFeatureFlaggingConfigurationSourceRequestTimeoutSeconds())
         .thenReturn(2.0D);
+    lenient().when(config.getFeatureFlaggingConfigurationSourceAgentlessBaseUrl()).thenReturn(null);
     lenient().when(config.getApiKey()).thenReturn("test-api-key");
     lenient().when(config.getSite()).thenReturn(site);
     lenient().when(config.getEnv()).thenReturn(env);