Document agentless Feature Flags delivery for Java and Node.js

config/_default/menus/main.en.yaml

@@ -6403,6 +6403,11 @@ menu:
       parent: feature_flags_concepts
       identifier: feature_flags_concepts_approvals
       weight: 321
+    - name: Configuration Sources
+      url: feature_flags/concepts/configuration_sources
+      parent: feature_flags_server
+      identifier: feature_flags_server_configuration_sources
+      weight: 200
     - name: Implementation Patterns
       url: feature_flags/implementation_patterns
       parent: feature_flags

content/en/feature_flags/_index.md

@@ -44,15 +44,15 @@ Feature flags enable you to toggle features on and off, conduct A/B/n testing, g
 
 If your flags are managed by LaunchDarkly, Split, ConfigCat, or another provider and you only want Datadog to record evaluated variants in RUM, see [RUM Feature Flag Tracking](/real_user_monitoring/feature_flag_tracking/) instead.
 
-Use a client-side SDK when the flag is evaluated in a browser, mobile app, or game client. Use a server-side SDK when the flag is evaluated in a backend service that receives flag configuration through the Datadog Agent and Remote Configuration.
+Use a client-side SDK when the flag is evaluated in a browser, mobile app, or game client. Use a server-side SDK when the flag is evaluated in a backend service. Supported server SDK versions receive configuration directly from Datadog by default or through Agent Remote Configuration when explicitly selected. See [Server SDK Configuration Sources][1].
 
 ### Credentials at a glance
 
 | Credential | Used by | Where it goes | Sensitive? |
 | --- | --- | --- | --- |
 | Client token | Browser, mobile, and game SDKs | Client application configuration | No — safe to ship in public client code |
 | Application ID | Browser and RUM-backed client SDKs | Client application configuration | No — public identifier |
-| API key | Datadog Agent for server-side Remote Configuration | Agent configuration only | Yes — keep server-side only |
+| API key | Server SDKs and the Datadog Agent | Application configuration for agentless delivery; Agent configuration for Remote Configuration | Yes—keep server-side only |
 
 Do not put API keys in browser, mobile, or game applications.
 
@@ -65,3 +65,5 @@ Feature Flags telemetry includes exposure events, flag evaluation metrics, and o
 ## Further reading
 
 {{< partial name="whats-next/whats-next.html" >}}
+
+[1]: /feature_flags/concepts/configuration_sources/

content/en/feature_flags/concepts/_index.md

@@ -12,6 +12,7 @@ Learn how Datadog Feature Flags work and how to configure flags, environments, t
     {{< nextlink href="/feature_flags/concepts/saved_filters" >}}Saved Filters{{< /nextlink >}}
     {{< nextlink href="/feature_flags/concepts/traffic_splitting" >}}Traffic Splitting and Randomization{{< /nextlink >}}
     {{< nextlink href="/feature_flags/concepts/distribution_channels" >}}Distribution Channels{{< /nextlink >}}
+    {{< nextlink href="/feature_flags/concepts/configuration_sources" >}}Server SDK Configuration Sources{{< /nextlink >}}
     {{< nextlink href="/feature_flags/concepts/flag_history" >}}Flag History{{< /nextlink >}}
     {{< nextlink href="/feature_flags/concepts/flag_graphs" >}}Feature Flag Graphs{{< /nextlink >}}
     {{< nextlink href="/feature_flags/concepts/stale_flags" >}}Stale Flags{{< /nextlink >}}

content/en/feature_flags/concepts/configuration_sources.md

@@ -0,0 +1,141 @@
+---
+title: Server SDK Configuration Sources
+description: Understand how Datadog Feature Flags server SDKs receive flag configuration.
+further_reading:
+- link: "/feature_flags/server/"
+  tag: "Documentation"
+  text: "Set up Server-Side Feature Flags"
+- link: "/feature_flags/implementation_patterns/serverless/"
+  tag: "Documentation"
+  text: "Use Feature Flags in serverless environments"
+- link: "/remote_configuration/"
+  tag: "Documentation"
+  text: "Learn about Remote Configuration"
+---
+
+Datadog Feature Flags server SDKs evaluate flags locally from Universal Flag Configuration (UFC). The _configuration source_ determines how the SDK receives UFC; it does not change OpenFeature evaluation semantics.
+
+## Get started with agentless delivery
+
+Agentless delivery is the default in supported server SDKs. To get started, use one of these minimum versions:
+
+| SDK | Minimum version |
+|---|---|
+| Java (`dd-java-agent` and `dd-openfeature`) | 1.65.0 |
+| Node.js `dd-trace` v5 | 5.116.0 |
+| Node.js `dd-trace` v6 | 6.5.0 |
+
+Configure only the API key and environment in the application process:
+
+{{< code-block lang="bash" >}}
+DD_API_KEY=<DATADOG_API_KEY>
+DD_ENV=<YOUR_ENVIRONMENT>
+{{< /code-block >}}
+
+Then initialize or access the Datadog OpenFeature provider in application code. See the [Java][2] or [Node.js][3] setup instructions.
+
+No configuration-source or provider-enable setting is required. Polling begins only when application code initializes or accesses the provider; installing or initializing the tracer alone does not create Feature Flags CDN traffic.
+
+<div class="alert alert-warning">The initial agentless releases support configuration delivery and local flag evaluation only. They do not send exposure events or aggregate <code>flagevaluation</code> events in agentless mode.</div>
+
+## Advanced configuration
+
+### Choose a configuration source
+
+| Mode | Configuration delivery | Activation | Agent requirement |
+|---|---|---|---|
+| `agentless` (default) | The SDK periodically fetches UFC from the Datadog-managed CDN over HTTPS. | Polling begins when application code initializes or accesses the Datadog OpenFeature provider. | No Datadog Agent is required for flag configuration. |
+| `remote_config` | The Datadog Agent receives UFC through Remote Configuration and delivers it to the SDK. | Selecting `remote_config` enables the Feature Flags Remote Configuration subscription. | Requires an Agent with Remote Configuration enabled. |
+
+Set `DD_FEATURE_FLAGS_CONFIGURATION_SOURCE` only when you want to select a source explicitly:
+
+{{< code-block lang="bash" >}}
+DD_FEATURE_FLAGS_CONFIGURATION_SOURCE=agentless
+{{< /code-block >}}
+
+The SDK resolves the source once during initialization. Restart the application to change sources.
+
+### Configure Agentless delivery
+
+If your organization is not on the default `datadoghq.com` site, set `DD_SITE` in the application process. The agentless source also supports these operational settings:
+
+| Environment variable | Default | Description |
+|---|---|---|
+| `DD_SITE` | `datadoghq.com` | Datadog site used to derive the agentless endpoint. |
+| `DD_FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_BASE_URL` | Datadog-managed endpoint | Overrides the agentless backend URL. |
+| `DD_FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_POLL_INTERVAL_SECONDS` | `30` | Time between completed polling attempts. |
+| `DD_FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_REQUEST_TIMEOUT_SECONDS` | `2` | Timeout for an individual configuration request. |
+| `DD_FEATURE_FLAGS_CONFIGURATION_SOURCE_AGENTLESS_EXTRA_HEADERS` | None | Adds headers to agentless configuration requests. |
+
+The SDK fetches configuration in the background and evaluates flags locally. Individual flag evaluations do not make network requests. The agentless source:
+
+- polls every 30 seconds by default;
+- uses a 2-second request timeout by default;
+- uses ETags to avoid downloading unchanged configuration;
+- preserves the last accepted configuration during temporary network or payload errors; and
+- prevents overlapping polls.
+
+Keep `DD_API_KEY` in a secret manager and expose it only to the application process that loads flag configuration. Agentless configuration delivery sends the API key directly from the application to Datadog over HTTPS.
+
+Datadog-managed agentless delivery is not available for Datadog for Government in these versions. Applications on that site continue to use caller-provided default values unless they use Agent Remote Configuration.
+
+### Enable or disable feature flags
+
+`DD_FEATURE_FLAGS_ENABLED` defaults to `true`, so new setups do not need to set it. Set it to `false` to disable the provider and both configuration delivery paths:
+
+{{< code-block lang="bash" >}}
+DD_FEATURE_FLAGS_ENABLED=false
+{{< /code-block >}}
+
+### Activation and billing
+
+Server Feature Flags billing is based on configuration requests made through Remote Configuration or the CDN. Installing the tracer does not activate either delivery path by itself.
+
+- With the default agentless source, CDN polling starts only when application code initializes or accesses the Datadog OpenFeature provider.
+- Explicitly selecting `remote_config` starts the Agent Feature Flags subscription. It does not require application code to initialize the provider.
+
+### Configuration precedence
+
+| Configuration | Result |
+|---|---|
+| `DD_FEATURE_FLAGS_ENABLED=false` | Disables the provider and both delivery paths, regardless of other settings. |
+| Explicit `DD_FEATURE_FLAGS_CONFIGURATION_SOURCE=agentless` | Selects CDN delivery. Polling begins when application code initializes or accesses the provider. |
+| Explicit `DD_FEATURE_FLAGS_CONFIGURATION_SOURCE=remote_config` | Selects Agent delivery and enables the Feature Flags Remote Configuration subscription. |
+| No source and `DD_EXPERIMENTAL_FLAGGING_PROVIDER_ENABLED=true` | Preserves Remote Configuration during the migration window. |
+| No source and `DD_EXPERIMENTAL_FLAGGING_PROVIDER_ENABLED=false` | Keeps the provider and both delivery paths disabled. |
+| Neither setting is present | Selects agentless delivery. Polling begins when application code initializes or accesses the provider. |
+
+### Use Agent remote configuration
+
+Set the source to `remote_config` to use Agent-managed delivery:
+
+{{< code-block lang="bash" >}}
+DD_FEATURE_FLAGS_CONFIGURATION_SOURCE=remote_config
+{{< /code-block >}}
+
+Configure the API key on the Agent, not in the application process. If Remote Configuration has been disabled on the Agent, re-enable it. See [Remote Configuration][1] for Agent setup and network requirements.
+
+### Migrate an existing remote configuration setup
+
+Existing customers who set `DD_EXPERIMENTAL_FLAGGING_PROVIDER_ENABLED=true` remain on Remote Configuration during a migration window. The setting is deprecated, and its removal version and timeline are communicated separately.
+
+If you set `DD_EXPERIMENTAL_FLAGGING_PROVIDER_ENABLED=true`, choose one of these paths:
+
+- **Stay on Agent Remote Configuration:** Set `DD_FEATURE_FLAGS_CONFIGURATION_SOURCE=remote_config`, then remove `DD_EXPERIMENTAL_FLAGGING_PROVIDER_ENABLED`. Your API key remains on the Agent.
+- **Move to agentless delivery:** Set `DD_FEATURE_FLAGS_CONFIGURATION_SOURCE=agentless`, configure `DD_API_KEY` and `DD_ENV` in the application, and set `DD_SITE` if your organization is not on the default site. Then remove `DD_EXPERIMENTAL_FLAGGING_PROVIDER_ENABLED`. CDN polling begins when application code initializes or accesses the provider.
+
+If you set `DD_EXPERIMENTAL_FLAGGING_PROVIDER_ENABLED=false`, replace it with `DD_FEATURE_FLAGS_ENABLED=false`.
+
+Explicit `DD_FEATURE_FLAGS_CONFIGURATION_SOURCE` values take precedence over the legacy setting. After the legacy setting is removed, an application without an explicit source uses agentless delivery. Set `remote_config` explicitly before that release if you want to remain on Agent delivery.
+
+### Future offline mode
+
+Offline mode is planned for applications that provide UFC JSON bytes at startup and do not make CDN or Remote Configuration network requests. It is not available in the initial agentless releases.
+
+## Further reading
+
+{{< partial name="whats-next/whats-next.html" >}}
+
+[1]: /remote_configuration/
+[2]: /feature_flags/server/java/
+[3]: /feature_flags/server/nodejs/