[receiver/datadog] Implement '/info' endpoint (#34772)

**Description:** <Describe what has changed.>
The Datadog agent exposes a `/info`
[endpoint](https://github.com/DataDog/datadog-agent/blob/ab888632bb71bcd57716e3428ed4c242ed7b9aaa/pkg/trace/api/api.go#L205),
communicating its available endpoints and capabilities.

This endpoint is used for the [trace
libraries](https://github.com/DataDog/dd-trace-java/blob/master/communication/src/main/java/datadog/communication/ddagent/DDAgentFeaturesDiscovery.java#L140-L173)
to infer the features available in the queried agent, and make some
decisions about the telemetry data at hand, including whether to send
[client
stats](https://github.com/DataDog/dd-trace-java/blob/master/communication/src/main/java/datadog/communication/ddagent/DDAgentFeaturesDiscovery.java#L40)
for the [local sampled
spans](https://github.com/DataDog/dd-trace-java/blob/master/dd-trace-core/src/main/java/datadog/trace/core/CoreTracer.java#L993-L1008)
used to calculate the [trace
metrics](https://docs.datadoghq.com/tracing/metrics/metrics_namespace/).

PS: in order to dynamically expose the available endpoints, this PR also
does a minor refactor on the endpoint configuration structure, defining
them in a `[]Endpoint` rather than registering them directly in the
`ServeMux`.

**Link to tracking Issue:**

**Testing:**

**Documentation:**

---------

Signed-off-by: Juraci Paixão Kröhling <[email protected]>
Co-authored-by: Juraci Paixão Kröhling <[email protected]>

Author: lopes-felipe

.chloggen/datadogreceiver-info-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 '/info' endpoint
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [34772]
+
+# (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: []

receiver/datadogreceiver/go.mod

@@ -4,6 +4,7 @@ go 1.22.0
 
 require (
 	github.com/DataDog/agent-payload/v5 v5.0.130
+	github.com/DataDog/datadog-agent/pkg/obfuscate v0.55.3
 	github.com/DataDog/datadog-agent/pkg/proto v0.56.0-rc.12
 	github.com/DataDog/datadog-api-client-go/v2 v2.29.0
 	github.com/open-telemetry/opentelemetry-collector-contrib/internal/exp/metrics v0.107.0
@@ -26,10 +27,14 @@ require (
 )
 
 require (
+	github.com/DataDog/datadog-go/v5 v5.5.0 // indirect
+	github.com/DataDog/go-sqllexer v0.0.12 // indirect
 	github.com/DataDog/zstd v1.5.2 // indirect
+	github.com/Microsoft/go-winio v0.5.1 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/dustin/go-humanize v1.0.0 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
 	github.com/fsnotify/fsnotify v1.7.0 // indirect
 	github.com/go-logr/logr v1.4.2 // indirect
@@ -52,7 +57,9 @@ require (
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/pdatautil v0.107.0 // indirect
+	github.com/outcaste-io/ristretto v0.2.1 // indirect
 	github.com/philhofer/fwd v1.1.2 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/prometheus/client_golang v1.19.1 // indirect
 	github.com/prometheus/client_model v0.6.1 // indirect
@@ -82,6 +89,7 @@ require (
 	go.opentelemetry.io/otel/sdk v1.28.0 // indirect
 	go.opentelemetry.io/otel/sdk/metric v1.28.0 // indirect
 	go.opentelemetry.io/otel/trace v1.28.0 // indirect
+	go.uber.org/atomic v1.10.0 // indirect
 	golang.org/x/net v0.28.0 // indirect
 	golang.org/x/oauth2 v0.21.0 // indirect
 	golang.org/x/sys v0.23.0 // indirect

receiver/datadogreceiver/go.sum

@@ -0,0 +1,44 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package translator // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/datadogreceiver/internal/translator"
+
+import (
+	"github.com/DataDog/datadog-agent/pkg/obfuscate"
+)
+
+type ReducedObfuscationConfig struct {
+	ElasticSearch        bool                      `json:"elastic_search"`
+	Mongo                bool                      `json:"mongo"`
+	SQLExecPlan          bool                      `json:"sql_exec_plan"`
+	SQLExecPlanNormalize bool                      `json:"sql_exec_plan_normalize"`
+	HTTP                 obfuscate.HTTPConfig      `json:"http"`
+	RemoveStackTraces    bool                      `json:"remove_stack_traces"`
+	Redis                obfuscate.RedisConfig     `json:"redis"`
+	Memcached            obfuscate.MemcachedConfig `json:"memcached"`
+}
+
+type ReducedConfig struct {
+	DefaultEnv             string                        `json:"default_env"`
+	TargetTPS              float64                       `json:"target_tps"`
+	MaxEPS                 float64                       `json:"max_eps"`
+	ReceiverPort           int                           `json:"receiver_port"`
+	ReceiverSocket         string                        `json:"receiver_socket"`
+	ConnectionLimit        int                           `json:"connection_limit"`
+	ReceiverTimeout        int                           `json:"receiver_timeout"`
+	MaxRequestBytes        int64                         `json:"max_request_bytes"`
+	StatsdPort             int                           `json:"statsd_port"`
+	MaxMemory              float64                       `json:"max_memory"`
+	MaxCPU                 float64                       `json:"max_cpu"`
+	AnalyzedSpansByService map[string]map[string]float64 `json:"analyzed_spans_by_service"`
+	Obfuscation            ReducedObfuscationConfig      `json:"obfuscation"`
+}
+
+type DDInfo struct {
+	Version          string         `json:"version"`
+	Endpoints        []string       `json:"endpoints"`
+	ClientDropP0s    bool           `json:"client_drop_p0s"`
+	SpanMetaStructs  bool           `json:"span_meta_structs"`
+	LongRunningSpans bool           `json:"long_running_spans"`
+	Config           *ReducedConfig `json:"config"`
+}