[receiver/cloudfoundry]: move datapoint level attributes to resource level (open-telemetry#34905)

**Description:** <Describe what has changed.>
Introduce a feature gate enable copying envelope tags to the metrics as
resource attributes instead of datapoint attributes.

**Link to tracking Issue:** open-telemetry#34824

---------

Signed-off-by: odubajDT <[email protected]>

Author: odubajDT

.chloggen/move-attributes.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: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: cloudfoundryreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Introduce a feature gate enable copying envelope tags to the metrics as resource attributes instead of datapoint attributes.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [34824]
+
+# (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/cloudfoundryreceiver/README.md

@@ -132,4 +132,35 @@ The receiver maps the envelope attribute tags to the following OpenTelemetry att
 * `instance_id` - numerical index of the origin. If origin is `rep` (`source_type` is `APP`) this is the application index. However, for other cases this is the instance index. 
 * `process_id` - process ID (GUID)
 * `process_instance_id` - unique ID of a process instance, should be treated as an opaque string
-* `process_type` - process type. Each application has exactly one process of type `web`, but many have any number of other processes
+* `process_type` - process type. Each application has exactly one process of type `web`, but many have any number of other processes
+
+## Feature Gate
+
+### `cloudfoundry.resourceAttributes.allow`
+
+#### Purpose
+
+The `cloudfoundry.resourceAttributes.allow` [feature gate](https://github.com/open-telemetry/opentelemetry-collector/blob/main/featuregate/README.md#collector-feature-gates) allows the envelope tags being copied to the metrics as resource attributes instead of datapoint attributes (default `false`).
+Therefore all `org.cloudfoundry.*` datapoint attributes won't be present anymore on metrics datapoint level, but on resource level instead, since the attributes describe the resource and not the datapoints itself.
+
+The `cloudfoundry.resourceAttributes.allow` feature gate is available since version `v0.117.0` and will be held at least for 2 versions (`v0.119.0`) until promoting to `beta` and another 2 vesions (`v0.121.0`) until promoting to `stable`.
+
+Below you can see the list of attributes that are present the resource level instead of datapoint level (when `cloudfoundry.resourceAttributes.allow` feature gate is enabled):
+
+```
+  - org.cloudfoundry.index
+  - org.cloudfoundry.ip
+  - org.cloudfoundry.deployment
+  - org.cloudfoundry.id
+  - org.cloudfoundry.job
+  - org.cloudfoundry.product
+  - org.cloudfoundry.instance_group
+  - org.cloudfoundry.instance_id
+  - org.cloudfoundry.origin
+  - org.cloudfoundry.system_domain
+  - org.cloudfoundry.source_id
+  - org.cloudfoundry.source_type
+  - org.cloudfoundry.process_type
+  - org.cloudfoundry.process_id
+  - org.cloudfoundry.process_instance_id
+```

receiver/cloudfoundryreceiver/converter.go

@@ -5,9 +5,11 @@ package cloudfoundryreceiver // import "github.com/open-telemetry/opentelemetry-
 
 import (
 	"fmt"
+	"slices"
 	"time"
 
 	"code.cloudfoundry.org/go-loggregator/rpc/loggregator_v2"
+	"go.opentelemetry.io/collector/featuregate"
 	"go.opentelemetry.io/collector/pdata/pcommon"
 	"go.opentelemetry.io/collector/pdata/plog"
 	"go.opentelemetry.io/collector/pdata/pmetric"
@@ -17,6 +19,31 @@ const (
 	attributeNamePrefix = "org.cloudfoundry."
 )
 
+var ResourceAttributesKeys = []string{
+	"index",
+	"ip",
+	"deployment",
+	"id",
+	"job",
+	"product",
+	"instance_group",
+	"instance_id",
+	"origin",
+	"system_domain",
+	"source_id",
+	"source_type",
+	"process_type",
+	"process_id",
+	"process_instance_id",
+}
+
+var allowResourceAttributes = featuregate.GlobalRegistry().MustRegister(
+	"cloudfoundry.resourceAttributes.allow",
+	featuregate.StageAlpha,
+	featuregate.WithRegisterDescription("When enabled, envelope tags are copied to the metrics as resource attributes instead of datapoint attributes"),
+	featuregate.WithRegisterFromVersion("v0.117.0"),
+)
+
 func convertEnvelopeToMetrics(envelope *loggregator_v2.Envelope, metricSlice pmetric.MetricSlice, startTime time.Time) {
 	namePrefix := envelope.Tags["origin"] + "."
 
@@ -28,7 +55,12 @@ func convertEnvelopeToMetrics(envelope *loggregator_v2.Envelope, metricSlice pme
 		dataPoint.SetDoubleValue(float64(message.Counter.GetTotal()))
 		dataPoint.SetTimestamp(pcommon.Timestamp(envelope.GetTimestamp()))
 		dataPoint.SetStartTimestamp(pcommon.NewTimestampFromTime(startTime))
-		copyEnvelopeAttributes(dataPoint.Attributes(), envelope)
+		if allowResourceAttributes.IsEnabled() {
+			attrs := getEnvelopeDataAttributes(envelope)
+			attrs.CopyTo(dataPoint.Attributes())
+		} else {
+			copyEnvelopeAttributes(dataPoint.Attributes(), envelope)
+		}
 	case *loggregator_v2.Envelope_Gauge:
 		for name, value := range message.Gauge.GetMetrics() {
 			metric := metricSlice.AppendEmpty()
@@ -37,7 +69,12 @@ func convertEnvelopeToMetrics(envelope *loggregator_v2.Envelope, metricSlice pme
 			dataPoint.SetDoubleValue(value.Value)
 			dataPoint.SetTimestamp(pcommon.Timestamp(envelope.GetTimestamp()))
 			dataPoint.SetStartTimestamp(pcommon.NewTimestampFromTime(startTime))
-			copyEnvelopeAttributes(dataPoint.Attributes(), envelope)
+			if allowResourceAttributes.IsEnabled() {
+				attrs := getEnvelopeDataAttributes(envelope)
+				attrs.CopyTo(dataPoint.Attributes())
+			} else {
+				copyEnvelopeAttributes(dataPoint.Attributes(), envelope)
+			}
 		}
 	}
 }
@@ -59,7 +96,12 @@ func convertEnvelopeToLogs(envelope *loggregator_v2.Envelope, logSlice plog.LogR
 	default:
 		return fmt.Errorf("unsupported envelope log type: %s", envelope.GetLog().GetType())
 	}
-	copyEnvelopeAttributes(log.Attributes(), envelope)
+	if allowResourceAttributes.IsEnabled() {
+		attrs := getEnvelopeDataAttributes(envelope)
+		attrs.CopyTo(log.Attributes())
+	} else {
+		copyEnvelopeAttributes(log.Attributes(), envelope)
+	}
 	return nil
 }
 
@@ -74,3 +116,29 @@ func copyEnvelopeAttributes(attributes pcommon.Map, envelope *loggregator_v2.Env
 		attributes.PutStr(attributeNamePrefix+"instance_id", envelope.InstanceId)
 	}
 }
+
+func getEnvelopeDataAttributes(envelope *loggregator_v2.Envelope) pcommon.Map {
+	attrs := pcommon.NewMap()
+	for key, value := range envelope.Tags {
+		if !slices.Contains(ResourceAttributesKeys, key) {
+			attrs.PutStr(attributeNamePrefix+key, value)
+		}
+	}
+	return attrs
+}
+
+func getEnvelopeResourceAttributes(envelope *loggregator_v2.Envelope) pcommon.Map {
+	attrs := pcommon.NewMap()
+	for key, value := range envelope.Tags {
+		if slices.Contains(ResourceAttributesKeys, key) {
+			attrs.PutStr(attributeNamePrefix+key, value)
+		}
+	}
+	if envelope.SourceId != "" {
+		attrs.PutStr(attributeNamePrefix+"source_id", envelope.SourceId)
+	}
+	if envelope.InstanceId != "" {
+		attrs.PutStr(attributeNamePrefix+"instance_id", envelope.InstanceId)
+	}
+	return attrs
+}