RUM-13568: [Cronet]: Supporting RUM <> APM integration for Cronet by satween · Pull Request #3136 · DataDog/dd-sdk-android

satween · 2026-01-20T16:21:35Z

What does this PR do?

In this PR we are copying the main logic from TracingInterceptor / DatadogInterceptor into the NetworkTracingInstrumentation in order to:

Support RUM <> APM integration for Cronet
Create a foundation for single network instrumentation logic that should be shared across several networking libraries in the future.

Motivation

Continuing to add an integration for Cronet library meanwhile preparing infrastructure to migrate OkHttp onto the same logic.

Additional Notes

Note that in this PR we are not supporting deep network instrumentation that is being done by TracingInterceptor in OkHttp. This logic will be supported in a further PR as this one is already pretty big.

NOTE: In this PR as an experiment an AI agent helped to write tests and some docs. I've made few iterations of a fixes for that but if you spot any issues - let me know. AI wasn't involved into production code development.

Review checklist (to be filled by reviewers)

Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
Make sure you discussed the feature or bugfix with the maintaining team in an Issue
Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)

satween · 2026-01-20T16:54:48Z

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chatgpt-codex-connector · 2026-01-20T21:02:11Z

...droid-cronet/src/main/kotlin/com/datadog/android/cronet/internal/DatadogUrlRequestBuilder.kt

    override fun addHeader(header: String, value: String?): UrlRequest.Builder = apply {
-        headers[header] = listOfNotNull(value)
-        delegate.addHeader(header, value)
+        val currentValues = headers[header]?.toMutableList() ?: mutableListOf()
+        if (value != null) {
+            currentValues.add(value)
+        }
+        headers[header] = currentValues


Forward added headers to the Cronet delegate

DatadogUrlRequestBuilder.addHeader() now only updates the local headers map and never forwards to delegate.addHeader. Later, buildCronetRequest() calls addHeaders(headers), which invokes this same override again, so the delegate builder never receives any headers. This means every Cronet request built through DatadogCronetEngine will drop user-supplied headers and tracing headers, breaking authentication and trace propagation. Consider forwarding to delegate.addHeader (or ensuring addHeaders writes to the delegate) so the actual request carries the headers.

Useful? React with 👍 / 👎.

Interesting catch, but the problem was bit deeper, fixed

codecov-commenter · 2026-01-22T14:22:11Z

Codecov Report

❌ Patch coverage is 75.07599% with 164 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.22%. Comparing base (39d8b4a) to head (0e81151).
⚠️ Report is 4 commits behind head on develop.

Files with missing lines	Patch %	Lines
...android/trace/internal/DatadogPropagationHelper.kt	62.24%	43 Missing and 11 partials ⚠️
...ndroid/trace/internal/ApmNetworkInstrumentation.kt	61.95%	27 Missing and 16 partials ⚠️
...oid/cronet/internal/DatadogCronetRequestContext.kt	89.22%	11 Missing ⚠️
...net/internal/DatadogRequestFinishedInfoListener.kt	16.67%	9 Missing and 1 partial ⚠️
.../com/datadog/android/cronet/DatadogCronetEngine.kt	72.73%	5 Missing and 4 partials ⚠️
...e/internal/net/NetworkTracingInstrumentationExt.kt	73.08%	4 Missing and 3 partials ⚠️
...tadog/android/cronet/internal/DatadogUrlRequest.kt	61.11%	1 Missing and 6 partials ⚠️
.../android/cronet/internal/DatadogRequestCallback.kt	76.00%	6 Missing ⚠️
...id/trace/ApmNetworkInstrumentationConfiguration.kt	93.94%	4 Missing ⚠️
.../instrumentation/network/HttpRequestInfoBuilder.kt	0.00%	3 Missing ⚠️
... and 7 more

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3136      +/-   ##
===========================================
+ Coverage    70.96%   71.22%   +0.27%     
===========================================
  Files          912      921       +9     
  Lines        33548    34109     +561     
  Branches      5640     5773     +133     
===========================================
+ Hits         23804    24294     +490     
- Misses        8173     8174       +1     
- Partials      1571     1641      +70

Files with missing lines	Coverage Δ
...droid/flags/openfeature/internal/FlagsClientExt.kt	`85.71% <ø> (ø)`
...uration/RumResourceInstrumentationConfiguration.kt	`100.00% <100.00%> (ø)`
.../android/rum/internal/monitor/DatadogRumMonitor.kt	`88.64% <ø> (-0.11%)`	⬇️
...oid/rum/internal/net/RumResourceInstrumentation.kt	`81.48% <100.00%> (+81.48%)`	⬆️
...om/datadog/trace/core/propagation/B3HttpCodec.java	`6.38% <ø> (ø)`
...tadog/trace/core/propagation/DatadogHttpCodec.java	`13.68% <ø> (ø)`
...m/datadog/trace/core/propagation/W3CHttpCodec.java	`12.99% <ø> (ø)`
...datadog/android/trace/DeterministicTraceSampler.kt	`100.00% <100.00%> (ø)`
...com/datadog/android/trace/TraceContextInjection.kt	`100.00% <100.00%> (ø)`
...og/android/trace/internal/DatadogTracingToolkit.kt	`33.33% <100.00%> (+11.90%)`	⬆️
... and 24 more

... and 34 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

dd-sdk-android-internal/src/main/java/com/datadog/android/internal/utils/LangExt.kt

...droid-rum/src/main/kotlin/com/datadog/android/rum/internal/net/RumResourceInstrumentation.kt

...ndroid-trace/src/main/kotlin/com/datadog/android/trace/internal/ApmNetworkInstrumentation.kt

0xnm · 2026-01-24T10:49:51Z

sample/kotlin/src/main/kotlin/com/datadog/android/sample/cronet/CronetImageFragment.kt

+    private val tracedHosts = listOf(
+        "datadoghq.com",
+        "127.0.0.1",
+        "storage.googleapis.com"


is it added for some validation? we don't own this host, so sending trace context there is useless

it's added in order to check that cronet is working with QUIC, RUM <> APM integration will not work for this host, but I want to keep this for sample app in order to send spans for it ( and check that APM is working with QUICK)

dd-sdk-android-core/api/apiSurface

...e/src/main/kotlin/com/datadog/android/api/instrumentation/network/HttpRequestInfoModifier.kt

dd-sdk-android-internal/src/main/java/com/datadog/android/internal/utils/LangExt.kt

0xnm · 2026-01-25T20:56:16Z

features/dd-sdk-android-rum/src/main/kotlin/com/datadog/android/rum/_RumInternalProxy.kt

            return builder.setInsightsCollector(insightsCollector)
        }
+
+        fun RumResourceInstrumentationConfiguration?.build(name: String): RumResourceInstrumentation? =


why is it a part of _RumInternalProxy? how it is supposed to be called?

I want to hide build method from users. This made for several reasons:

build() - basically useless method, it does not add any information to the builder

Integrations (Cronet and OkHttp) should set their names into the instrumentation.

how it is supposed to be called?

val rumResourceInstrumentation = with(_RumInternalProxy) { rumInstrumentationConfiguration.build(CRONET_NETWORK_INSTRUMENTATION_NAME) }

I'm wondering how it looks like in a java bytecode. Are you sure that rumInstrumentationConfiguration.build(CRONET_NETWORK_INSTRUMENTATION_NAME) call is not possible outside of _RumInternalProxy receiver scope?

First time I see such trick given that visibility of extension function is public.

After several experiments with api calls - I decided to move back to more classic approach, as in current state build method is still visible for customers but they cannot call it which could be confusing

features/dd-sdk-android-trace/api/apiSurface

...-android-okhttp/src/main/kotlin/com/datadog/android/okhttp/internal/OkHttpHttpRequestInfo.kt

integrations/dd-sdk-android-cronet/api/apiSurface

...id-cronet/src/main/kotlin/com/datadog/android/cronet/internal/DatadogCronetRequestContext.kt

0xnm

I partially covered this PR, but will continue review later.

...re/src/main/kotlin/com/datadog/android/api/instrumentation/network/HttpRequestInfoBuilder.kt

0xnm · 2026-02-04T04:06:27Z

features/dd-sdk-android-rum/src/main/kotlin/com/datadog/android/rum/_RumInternalProxy.kt

            return builder.setInsightsCollector(insightsCollector)
        }
+
+        fun RumResourceInstrumentationConfiguration?.build(name: String): RumResourceInstrumentation? =


I'm wondering how it looks like in a java bytecode. Are you sure that rumInstrumentationConfiguration.build(CRONET_NETWORK_INSTRUMENTATION_NAME) call is not possible outside of _RumInternalProxy receiver scope?

First time I see such trick given that visibility of extension function is public.

features/dd-sdk-android-trace/api/apiSurface

...id-trace/src/main/kotlin/com/datadog/android/trace/ApmNetworkInstrumentationConfiguration.kt

...ndroid-trace/src/main/kotlin/com/datadog/android/trace/internal/ApmNetworkInstrumentation.kt

integrations/dd-sdk-android-cronet/api/apiSurface

...id-cronet/src/main/kotlin/com/datadog/android/cronet/internal/DatadogCronetRequestContext.kt

...ndroid-trace/src/main/kotlin/com/datadog/android/trace/internal/ApmNetworkInstrumentation.kt

...d-sdk-android-trace/src/main/kotlin/com/datadog/android/trace/internal/net/TracerProvider.kt

0xnm · 2026-02-05T09:04:00Z

...d-sdk-android-trace/src/main/kotlin/com/datadog/android/trace/internal/net/TracerProvider.kt

+    private val localTracerReference: AtomicReference<DatadogTracer> = AtomicReference()
+
+    @Synchronized
+    @Suppress("UnsafeThirdPartyFunctionCall") // updateAndGet is safe


there is no updateAndGet usage though

...d-sdk-android-trace/src/main/kotlin/com/datadog/android/trace/internal/net/TracerProvider.kt

0xnm · 2026-02-05T16:59:29Z

features/dd-sdk-android-rum/src/test/kotlin/com/datadog/android/rum/RumInternalProxyTest.kt

+        val result = with(_RumInternalProxy.Companion) {
+            builder.createInstrumentation(fakeInstrumentationName)
+        }


need to update this

0xnm · 2026-02-05T17:00:54Z

features/dd-sdk-android-trace/api/apiSurface

+  fun setTraceSampler(com.datadog.android.core.sampling.Sampler<com.datadog.android.trace.api.span.DatadogSpan>)
+  fun setTraceContextInjection(TraceContextInjection)
+  fun set404ResourcesRedacted(Boolean)
+  fun setTracingScope(ApmNetworkTracingScope)


very nit: tracing vs trace above, but maybe it is okay if we think of tracing as a process, not as of trace as item

0xnm · 2026-02-05T17:03:19Z

...id-trace/src/main/kotlin/com/datadog/android/trace/ApmNetworkInstrumentationConfiguration.kt

+     * Sets the tracing scope for network instrumentation.
+     *
+     * This controls how detailed the tracing will be:
+     * - [ApmNetworkTracingScope.DETAILED]: Traces both application-level requests and internal


maybe ALL is a better name? Also this separation applies to OkHttp only, does Cronet also have similar?

0xnm · 2026-02-05T17:04:18Z

...res/dd-sdk-android-trace/src/main/kotlin/com/datadog/android/trace/ApmNetworkTracingScope.kt

+
+    /**
+     * Only application level request is gonna be traced.
+     * In this mode the Datadog SDK still able to link trace spans to Rum.Resources making possible to navigate


Suggested change

* In this mode the Datadog SDK still able to link trace spans to Rum.Resources making possible to navigate

* In this mode the Datadog SDK still able to link trace spans to RUM Resources making possible to navigate

0xnm · 2026-02-05T17:05:47Z

...ndroid-trace/src/main/kotlin/com/datadog/android/trace/internal/ApmNetworkInstrumentation.kt

+                "onRequestIntercepted callback, leading to infinite recursion."
+
+        internal const val ERROR_REQUEST_INFO_IS_NOT_MUTABLE =
+            "RequestInfo is not mutable. Your requests won't be traced."


should it be HttpRequestInfo?

0xnm · 2026-02-05T17:09:36Z

...ndroid-trace/src/test/kotlin/com/datadog/android/trace/internal/DatadogTracingToolkitTest.kt

+        val builder = ApmNetworkInstrumentationConfiguration(fakeTracedHosts)
+
+        // When
+        val result: ApmNetworkInstrumentation = with(DatadogTracingToolkit) {


with is redundant here

0xnm · 2026-02-05T17:10:29Z

...oid-trace/src/test/kotlin/com/datadog/android/trace/internal/DatadogPropagationHelperTest.kt

+    @Test
+    fun `M return false W isExtractedContext() {non-extracted DatadogSpanContextAdapter}`() {
+        // Given
+        val mockAgentSpanContext: com.datadog.trace.bootstrap.instrumentation.api.AgentSpan.Context = mock()


Suggested change

val mockAgentSpanContext: com.datadog.trace.bootstrap.instrumentation.api.AgentSpan.Context = mock()

val mockAgentSpanContext = mock<AgentSpan.Context>()

0xnm · 2026-02-05T17:11:16Z

...oid-trace/src/test/kotlin/com/datadog/android/trace/internal/DatadogPropagationHelperTest.kt

+                any<
+                    (
+                        HttpRequestInfo,
+                        (String, String) -> Boolean
+                    ) -> Unit
+                    >()


nit: seems like formatting gone wrong

0xnm · 2026-02-05T17:15:13Z

...-android-cronet/src/test/kotlin/com/datadog/android/cronet/DatadogCronetEngineBuilderTest.kt

    @OptIn(ExperimentalRumApi::class)
    @Test
-    fun `M propagate RumResourceAttributesProvider W setRumResourceAttributesProvider()`() {
+    fun `M propagate RumResourceAttributesProvider W setCustomRumInstrumentation()`() {


there is no such method

0xnm · 2026-02-05T17:15:28Z

...-android-cronet/src/test/kotlin/com/datadog/android/cronet/DatadogCronetEngineBuilderTest.kt

    @OptIn(ExperimentalRumApi::class)
    @Test
-    fun `M propagate sdkInstanceName W setSdkInstanceName()`(@StringForgery sdkInstanceName: String) {
+    fun `M propagate sdkInstanceName W setCustomRumInstrumentation()`(@StringForgery sdkInstanceName: String) {


satween requested a review from a team as a code owner January 20, 2026 16:21

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satween force-pushed the tvaleev/feature/RUM-13568-apm-dependencies branch 5 times, most recently from 21d8777 to 3db3a62 Compare January 22, 2026 13:41

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satween force-pushed the tvaleev/feature/RUM-13568-apm-dependencies branch 2 times, most recently from 4ef7d94 to 6c726f5 Compare February 2, 2026 16:25

satween requested review from 0xnm and ambushwork February 2, 2026 16:26

satween force-pushed the tvaleev/feature/RUM-13568-apm-dependencies branch from 6c726f5 to 0e81151 Compare February 2, 2026 18:36

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RUM-13568: Supporting tracing logic

f636bd2

satween force-pushed the tvaleev/feature/RUM-13568-apm-dependencies branch from 0e81151 to f636bd2 Compare February 5, 2026 16:09

satween requested a review from 0xnm February 5, 2026 16:09

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	* In this mode the Datadog SDK still able to link trace spans to Rum.Resources making possible to navigate
	* In this mode the Datadog SDK still able to link trace spans to RUM Resources making possible to navigate

	val mockAgentSpanContext: com.datadog.trace.bootstrap.instrumentation.api.AgentSpan.Context = mock()
	val mockAgentSpanContext = mock<AgentSpan.Context>()

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satween commented Jan 20, 2026

What does this PR do?

Motivation

Additional Notes

Review checklist (to be filled by reviewers)

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