[receiver/nopreceiver] Add the nopreceiver (#9446)

**Description:**

Add the nopreceiver. This can be helpful if a user wants to start the
Collector with a dummy pipeline to only enable extensions. It could also
be used to start a dynamically-configured Collector that starts with no
config and waits to receive its config from a confmap.Provider that
supports reloads.

**Link to tracking Issue:**

Works toward
#7316

**Testing:**

Added lifecycle tests; the receiver doesn't do anything.

**Documentation:**

Added a readme for the component.

.chloggen/nopreceiver.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: 'new_component'
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: receiver/nop
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add the `nopreceiver` to serve as a placeholder receiver in a pipeline
+
+# One or more tracking issues or pull requests related to the change
+issues: [7316]
+
+# (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: This is primarily useful for starting the Collector with only extensions enabled.
+
+# 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: []

Makefile

@@ -285,6 +285,7 @@ check-contrib:
 		-replace go.opentelemetry.io/collector/processor/batchprocessor=$(CURDIR)/processor/batchprocessor  \
 		-replace go.opentelemetry.io/collector/processor/memorylimiterprocessor=$(CURDIR)/processor/memorylimiterprocessor  \
 		-replace go.opentelemetry.io/collector/receiver=$(CURDIR)/receiver  \
+		-replace go.opentelemetry.io/collector/receiver/nopreceiver=$(CURDIR)/receiver/nopreceiver  \
 		-replace go.opentelemetry.io/collector/receiver/otlpreceiver=$(CURDIR)/receiver/otlpreceiver  \
 		-replace go.opentelemetry.io/collector/semconv=$(CURDIR)/semconv  \
 		-replace go.opentelemetry.io/collector/service=$(CURDIR)/service"
@@ -339,6 +340,7 @@ restore-contrib:
 		-dropreplace go.opentelemetry.io/collector/processor/batchprocessor  \
 		-dropreplace go.opentelemetry.io/collector/processor/memorylimiterprocessor  \
 		-dropreplace go.opentelemetry.io/collector/receiver  \
+		-dropreplace go.opentelemetry.io/collector/receiver/nopreceiver  \
 		-dropreplace go.opentelemetry.io/collector/receiver/otlpreceiver  \
 		-dropreplace go.opentelemetry.io/collector/semconv  \
 		-dropreplace go.opentelemetry.io/collector/service"

cmd/builder/internal/builder/main_test.go

@@ -81,6 +81,7 @@ func TestGenerateAndCompile(t *testing.T) {
 		fmt.Sprintf("go.opentelemetry.io/collector/processor/batchprocessor => %s/processor/batchprocessor", workspaceDir),
 		fmt.Sprintf("go.opentelemetry.io/collector/processor/memorylimiterprocessor => %s/processor/memorylimiterprocessor", workspaceDir),
 		fmt.Sprintf("go.opentelemetry.io/collector/receiver => %s/receiver", workspaceDir),
+		fmt.Sprintf("go.opentelemetry.io/collector/receiver/nopreceiver => %s/receiver/nopreceiver", workspaceDir),
 		fmt.Sprintf("go.opentelemetry.io/collector/receiver/otlpreceiver => %s/receiver/otlpreceiver", workspaceDir),
 		fmt.Sprintf("go.opentelemetry.io/collector/otelcol => %s/otelcol", workspaceDir),
 		fmt.Sprintf("go.opentelemetry.io/collector/pdata => %s/pdata", workspaceDir),

cmd/otelcorecol/builder-config.yaml

@@ -6,6 +6,7 @@ dist:
   otelcol_version: 0.96.0
 
 receivers:
+  - gomod: go.opentelemetry.io/collector/receiver/nopreceiver v0.96.0
   - gomod: go.opentelemetry.io/collector/receiver/otlpreceiver v0.96.0
 exporters:
   - gomod: go.opentelemetry.io/collector/exporter/debugexporter v0.96.0
@@ -62,6 +63,7 @@ replaces:
   - go.opentelemetry.io/collector/pdata => ../../pdata
   - go.opentelemetry.io/collector/processor => ../../processor
   - go.opentelemetry.io/collector/receiver => ../../receiver
+  - go.opentelemetry.io/collector/receiver/nopreceiver => ../../receiver/nopreceiver
   - go.opentelemetry.io/collector/receiver/otlpreceiver => ../../receiver/otlpreceiver
   - go.opentelemetry.io/collector/processor/batchprocessor => ../../processor/batchprocessor
   - go.opentelemetry.io/collector/processor/memorylimiterprocessor => ../../processor/memorylimiterprocessor

cmd/otelcorecol/go.mod

@@ -24,6 +24,7 @@ require (
 	go.opentelemetry.io/collector/processor/batchprocessor v0.96.0
 	go.opentelemetry.io/collector/processor/memorylimiterprocessor v0.96.0
 	go.opentelemetry.io/collector/receiver v0.96.0
+	go.opentelemetry.io/collector/receiver/nopreceiver v0.96.0
 	go.opentelemetry.io/collector/receiver/otlpreceiver v0.96.0
 	go.uber.org/goleak v1.3.0
 	golang.org/x/sys v0.18.0
@@ -208,6 +209,8 @@ replace go.opentelemetry.io/collector/processor => ../../processor
 
 replace go.opentelemetry.io/collector/receiver => ../../receiver
 
+replace go.opentelemetry.io/collector/receiver/nopreceiver => ../../receiver/nopreceiver
+
 replace go.opentelemetry.io/collector/receiver/otlpreceiver => ../../receiver/otlpreceiver
 
 replace go.opentelemetry.io/collector/processor/batchprocessor => ../../processor/batchprocessor

receiver/nopreceiver/Makefile

@@ -0,0 +1 @@
+include ../../Makefile.Common

receiver/nopreceiver/README.md

@@ -0,0 +1,24 @@
+# No-op Receiver
+
+<!-- status autogenerated section -->
+| Status        |           |
+| ------------- |-----------|
+| Stability     | [development]: traces, metrics, logs   |
+| Distributions | [] |
+| Issues        | [![Open issues](https://img.shields.io/github/issues-search/open-telemetry/opentelemetry-collector-contrib?query=is%3Aissue%20is%3Aopen%20label%3Areceiver%2Fnop%20&label=open&color=orange&logo=opentelemetry)](https://github.com/open-telemetry/opentelemetry-collector-contrib/issues?q=is%3Aopen+is%3Aissue+label%3Areceiver%2Fnop) [![Closed issues](https://img.shields.io/github/issues-search/open-telemetry/opentelemetry-collector-contrib?query=is%3Aissue%20is%3Aclosed%20label%3Areceiver%2Fnop%20&label=closed&color=blue&logo=opentelemetry)](https://github.com/open-telemetry/opentelemetry-collector-contrib/issues?q=is%3Aclosed+is%3Aissue+label%3Areceiver%2Fnop) |
+
+[development]: https://github.com/open-telemetry/opentelemetry-collector#development
+<!-- end autogenerated section -->
+
+Serves as a placeholder receiver in a pipeline. This can be useful if you want
+to e.g. start a Collector with only extensions enabled.
+
+## Getting Started
+
+All that is required to enable the No-op receiver is to include it in the
+receiver definitions. It takes no configuration.
+
+```yaml
+receivers:
+  nop:
+```

receiver/nopreceiver/doc.go

@@ -0,0 +1,7 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+//go:generate mdatagen metadata.yaml
+
+// Package nopreceiver serves as a placeholder receiver.
+package nopreceiver // import "go.opentelemetry.io/collector/receiver/nopreceiver"

receiver/nopreceiver/go.mod

@@ -0,0 +1,70 @@
+module go.opentelemetry.io/collector/receiver/nopreceiver
+
+go 1.21
+
+toolchain go1.21.6
+
+require (
+	github.com/stretchr/testify v1.9.0
+	go.opentelemetry.io/collector/component v0.96.0
+	go.opentelemetry.io/collector/confmap v0.96.0
+	go.opentelemetry.io/collector/consumer v0.96.0
+	go.opentelemetry.io/collector/receiver v0.96.0
+	go.opentelemetry.io/otel/metric v1.24.0
+	go.opentelemetry.io/otel/trace v1.24.0
+)
+
+require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.2.0 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/go-logr/logr v1.4.1 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/go-viper/mapstructure/v2 v2.0.0-alpha.1 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/golang/protobuf v1.5.3 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/knadh/koanf/maps v0.1.1 // indirect
+	github.com/knadh/koanf/providers/confmap v0.1.0 // indirect
+	github.com/knadh/koanf/v2 v2.1.0 // 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/pmezard/go-difflib v1.0.0 // indirect
+	github.com/prometheus/client_golang v1.19.0 // indirect
+	github.com/prometheus/client_model v0.6.0 // indirect
+	github.com/prometheus/common v0.48.0 // indirect
+	github.com/prometheus/procfs v0.12.0 // indirect
+	go.opentelemetry.io/collector/config/configtelemetry v0.96.0 // indirect
+	go.opentelemetry.io/collector/pdata v1.3.0 // indirect
+	go.opentelemetry.io/otel v1.24.0 // indirect
+	go.opentelemetry.io/otel/exporters/prometheus v0.46.0 // indirect
+	go.opentelemetry.io/otel/sdk v1.24.0 // indirect
+	go.opentelemetry.io/otel/sdk/metric v1.24.0 // indirect
+	go.uber.org/multierr v1.11.0 // indirect
+	go.uber.org/zap v1.27.0 // indirect
+	golang.org/x/net v0.21.0 // indirect
+	golang.org/x/sys v0.17.0 // indirect
+	golang.org/x/text v0.14.0 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20240123012728-ef4313101c80 // indirect
+	google.golang.org/grpc v1.62.1 // indirect
+	google.golang.org/protobuf v1.33.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
+
+replace go.opentelemetry.io/collector/component => ../../component
+
+replace go.opentelemetry.io/collector/confmap => ../../confmap
+
+replace go.opentelemetry.io/collector/consumer => ../../consumer
+
+replace go.opentelemetry.io/collector/receiver => ../
+
+replace go.opentelemetry.io/collector/pdata => ../../pdata
+
+replace go.opentelemetry.io/collector/config/configtelemetry => ../../config/configtelemetry
+
+replace go.opentelemetry.io/collector => ../..
+
+replace go.opentelemetry.io/collector/featuregate => ../../featuregate