[receiver/datadogreceiver] Configure /intake endpoint (open-telemetry#39787)

#### Description

Datadog's `/intake` endpoint is used by agents to record information
about the system they're running on. It's not a metrics/logs/traces
endpoint, but instead accepts metadata about a specific host that a
`datadog-agent` is running on. This meatadata is used by Datadog to
enrich metrics for a specific host (e.g. host-specific tags that should
be associated with all metrics from that host).

While supporting `/intake` isn't striclty necessary to ingest
metrics/logs/traces, it means that [pointing a `datadog-agent` at an
OpenTelemetry
Collector](https://github.com/DataDog/datadog-agent/blob/7.64.0/pkg/config/config_template.yaml#L40)
will not work as expected, because all metrics submitted by the agent
will be missing their host tags. By adding the ability to proxy
`/intake` calls to Datadog itself, we enable this
`datadog-agent`→`otelcol` workflow.

The default behaviour maintains backwards-compatibility - if you don't
specify an intake configuration, then intake calls aren't processed.

#### Testing

Ran both simulated calls and ran a `datadog-agent` against this
receiver. The collector properly received and proxied the `/intake`
calls (as could be seen in the Datadog hosts dashboard).

#### Documentation

Updated the README for the receiver.

Author: goakley

.chloggen/datadogreceiver_intake-endpoint.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: datadogreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Implement the `/intake` endpoint
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [39787]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

cmd/opampsupervisor/go.mod

@@ -81,12 +81,12 @@ require (
 	github.com/leodido/go-syslog/v4 v4.2.0 // indirect
 	github.com/leodido/ragel-machinery v0.0.0-20190525184631-5f46317e436b // indirect
 	github.com/lightstep/go-expohisto v1.0.0 // indirect
-	github.com/lufia/plan9stats v0.0.0-20240226150601-1dcf7310316a // indirect
+	github.com/lufia/plan9stats v0.0.0-20240909124753-873cd0166683 // indirect
 	github.com/magefile/mage v1.15.0 // indirect
 	github.com/mitchellh/copystructure v1.2.0 // indirect
 	github.com/mitchellh/reflectwalk v1.0.2 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
-	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee // indirect
 	github.com/mostynb/go-grpc-compression v1.2.3 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/open-telemetry/opentelemetry-collector-contrib/connector/routingconnector v0.128.0 // indirect
@@ -129,7 +129,7 @@ require (
 	github.com/splunk/stef/go/pdata v0.0.6 // indirect
 	github.com/splunk/stef/go/pkg v0.0.6 // indirect
 	github.com/tklauser/go-sysconf v0.3.14 // indirect
-	github.com/tklauser/numcpus v0.8.0 // indirect
+	github.com/tklauser/numcpus v0.9.0 // indirect
 	github.com/twmb/murmur3 v1.1.8 // indirect
 	github.com/ua-parser/uap-go v0.0.0-20240611065828-3a4781585db6 // indirect
 	github.com/valyala/fastjson v1.6.4 // indirect
@@ -216,7 +216,7 @@ require (
 	go.opentelemetry.io/otel/sdk/metric v1.36.0 // indirect
 	go.opentelemetry.io/proto/otlp v1.6.0 // indirect
 	golang.org/x/crypto v0.39.0 // indirect
-	golang.org/x/exp v0.0.0-20250210185358-939b2ce775ac // indirect
+	golang.org/x/exp v0.0.0-20250408133849-7e4ce0ab07d0 // indirect
 	golang.org/x/net v0.41.0 // indirect
 	golang.org/x/sync v0.15.0 // indirect
 	golang.org/x/text v0.26.0 // indirect
@@ -324,3 +324,13 @@ replace github.com/open-telemetry/opentelemetry-collector-contrib/receiver/stefr
 replace github.com/open-telemetry/opentelemetry-collector-contrib/processor/deltatocumulativeprocessor => ../../processor/deltatocumulativeprocessor
 
 replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/gopsutilenv => ../../internal/gopsutilenv
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/metadataproviders => ../../internal/metadataproviders
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/k8sconfig => ../../internal/k8sconfig
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/datadog => ../../internal/datadog
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/datadog => ../../pkg/datadog
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/aws/ecsutil => ../../internal/aws/ecsutil

cmd/opampsupervisor/go.sum

@@ -92,13 +92,13 @@ require (
 	github.com/leodido/ragel-machinery v0.0.0-20190525184631-5f46317e436b // indirect
 	github.com/lestrrat-go/strftime v1.1.0 // indirect
 	github.com/lightstep/go-expohisto v1.0.0 // indirect
-	github.com/lufia/plan9stats v0.0.0-20240226150601-1dcf7310316a // indirect
+	github.com/lufia/plan9stats v0.0.0-20240909124753-873cd0166683 // indirect
 	github.com/magefile/mage v1.15.0 // indirect
 	github.com/minio/sha256-simd v1.0.1 // indirect
 	github.com/mitchellh/copystructure v1.2.0 // indirect
 	github.com/mitchellh/reflectwalk v1.0.2 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
-	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee // indirect
 	github.com/mostynb/go-grpc-compression v1.2.3 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/open-telemetry/opentelemetry-collector-contrib/connector/routingconnector v0.128.0 // indirect
@@ -141,7 +141,7 @@ require (
 	github.com/splunk/stef/go/pdata v0.0.6 // indirect
 	github.com/splunk/stef/go/pkg v0.0.6 // indirect
 	github.com/tklauser/go-sysconf v0.3.14 // indirect
-	github.com/tklauser/numcpus v0.8.0 // indirect
+	github.com/tklauser/numcpus v0.9.0 // indirect
 	github.com/twmb/murmur3 v1.1.8 // indirect
 	github.com/ua-parser/uap-go v0.0.0-20240611065828-3a4781585db6 // indirect
 	github.com/valyala/fastjson v1.6.4 // indirect
@@ -231,7 +231,7 @@ require (
 	go.opentelemetry.io/proto/otlp v1.6.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
 	golang.org/x/crypto v0.39.0 // indirect
-	golang.org/x/exp v0.0.0-20250210185358-939b2ce775ac // indirect
+	golang.org/x/exp v0.0.0-20250408133849-7e4ce0ab07d0 // indirect
 	golang.org/x/net v0.41.0 // indirect
 	golang.org/x/sys v0.33.0 // indirect
 	golang.org/x/text v0.26.0 // indirect
@@ -346,3 +346,13 @@ replace github.com/open-telemetry/opentelemetry-collector-contrib/receiver/stefr
 replace github.com/open-telemetry/opentelemetry-collector-contrib/processor/deltatocumulativeprocessor => ../../../processor/deltatocumulativeprocessor
 
 replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/gopsutilenv => ../../../internal/gopsutilenv
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/datadog => ../../../pkg/datadog
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/metadataproviders => ../../../internal/metadataproviders
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/k8sconfig => ../../../internal/k8sconfig
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/datadog => ../../../internal/datadog
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/internal/aws/ecsutil => ../../../internal/aws/ecsutil

exporter/elasticsearchexporter/integrationtest/go.mod

@@ -38,6 +38,11 @@ extension/storage
 pkg/stanza
 pkg/translator/jaeger
 receiver/carbonreceiver
+internal/aws/ecsutil
+internal/k8sconfig
+internal/metadataproviders
+internal/datadog
+pkg/datadog
 receiver/datadogreceiver
 receiver/jaegerreceiver
 receiver/signalfxreceiver
@@ -57,11 +62,6 @@ confmap/provider/s3provider
 confmap/provider/secretsmanagerprovider
 internal/filter
 connector/countconnector
-internal/aws/ecsutil
-internal/k8sconfig
-internal/metadataproviders
-internal/datadog
-pkg/datadog
 pkg/xk8stest
 processor/k8sattributesprocessor
 pkg/sampling

exporter/elasticsearchexporter/integrationtest/go.sum

@@ -67,6 +67,26 @@ All config params here are valid as well
 
 https://github.com/open-telemetry/opentelemetry-collector/tree/main/config/confighttp#server-configuration
 
+### `/intake` Config
+
+The `datadog-agent` forwards metadata about its runtime environment via the `/intake` API endpoint.
+This receiver supports receiving this data and forwarding it directly to Datadog.
+(Note that this data isn't telemetry data, so it does not go through any configured collector pipelines.)
+
+This feature can be enabled in the config:
+
+```
+receivers:
+  datadog:
+    intake:
+      behavior: proxy
+      proxy:
+        api:
+          key: ${env:DD_API_KEY}
+          site: datadoghq.com
+          fail_on_invalid_key: true
+```
+
 ### Default Attributes
 
 - `dd.span.Resource`: The datadog resource name (as distinct from the span name)
@@ -90,15 +110,15 @@ Format example can be found [here](./internal/translator/traces_translator_test.
 
 **Metrics**
 
-| Datadog API Endpoint        | Status      | Notes |
-|-----------------------------|-------------|-------|
-| /api/v1/series              | Development |       |
-| /api/v2/series              | Development |       |
-| /api/v1/check_run           | Development |       |
-| /api/v1/sketches            | Development |       |
-| /api/beta/sketches          | Development |       |
-| /api/v1/distribution_points | Development |       |
-| /intake                     | Development |       |
+| Datadog API Endpoint        | Status      | Notes                      |
+|-----------------------------|-------------|----------------------------|
+| /api/v1/series              | Development |                            |
+| /api/v2/series              | Development |                            |
+| /api/v1/check_run           | Development |                            |
+| /api/v1/sketches            | Development |                            |
+| /api/beta/sketches          | Development |                            |
+| /api/v1/distribution_points | Development |                            |
+| /intake                     | Development | Support for proxying calls |
 
 ### Temporality considerations