[extension] Move optional interfaces to extensioncapabilities (#11000)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

<!-- Issue number if applicable -->

Moves extension optional interfaces to a new module,
`extensioncapabilities`.

The intent is to be able to evolve these interfaces independently from
the core interfaces on core.

These are used by at most one component/project, so I think they are not
mature yet for 1.0

---------

Co-authored-by: Evan Bradley <11745660+evan-bradley@users.noreply.github.com>

.chloggen/mx-psi_extensioncapabilities-depr.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: deprecation
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: extension
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Deprecate `extension.ConfigWatcher`, `extension.PipelineWatcher` and `extension.Dependent` in favor of equivalents in the `extensioncapabilities` module.
+
+# One or more tracking issues or pull requests related to the change
+issues: [11000]
+
+# (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:
+
+# 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: [api]

.chloggen/mx-psi_extensioncapabilities.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: extensioncapabilities
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Create a new module for optional extension capabilities.
+
+# One or more tracking issues or pull requests related to the change
+issues: [11000]
+
+# (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:
+
+# 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: [api]

Makefile

@@ -293,6 +293,7 @@ check-contrib:
 		-replace go.opentelemetry.io/collector/extension=$(CURDIR)/extension  \
 		-replace go.opentelemetry.io/collector/extension/auth=$(CURDIR)/extension/auth  \
 		-replace go.opentelemetry.io/collector/extension/experimental/storage=$(CURDIR)/extension/experimental/storage  \
+		-replace go.opentelemetry.io/collector/extension/extensioncapabilities=$(CURDIR)/extension/extensioncapabilities  \
 		-replace go.opentelemetry.io/collector/extension/memorylimiterextension=$(CURDIR)/extension/memorylimiterextension  \
 		-replace go.opentelemetry.io/collector/extension/zpagesextension=$(CURDIR)/extension/zpagesextension  \
 		-replace go.opentelemetry.io/collector/featuregate=$(CURDIR)/featuregate  \

cmd/builder/internal/builder/main_test.go

@@ -74,6 +74,7 @@ var (
 		"/extension",
 		"/extension/auth",
 		"/extension/experimental/storage",
+		"/extension/extensioncapabilities",
 		"/extension/zpagesextension",
 		"/featuregate",
 		"/internal/globalgates",

cmd/builder/test/core.builder.yaml

@@ -50,6 +50,7 @@ replaces:
   - go.opentelemetry.io/collector/extension => ${WORKSPACE_DIR}/extension
   - go.opentelemetry.io/collector/extension/auth => ${WORKSPACE_DIR}/extension/auth
   - go.opentelemetry.io/collector/extension/experimental/storage => ${WORKSPACE_DIR}/extension/experimental/storage
+  - go.opentelemetry.io/collector/extension/extensioncapabilities => ${WORKSPACE_DIR}/extension/extensioncapabilities
   - go.opentelemetry.io/collector/extension/zpagesextension => ${WORKSPACE_DIR}/extension/zpagesextension
   - go.opentelemetry.io/collector/featuregate => ${WORKSPACE_DIR}/featuregate
   - go.opentelemetry.io/collector/internal/globalgates => ${WORKSPACE_DIR}/internal/globalgates

cmd/otelcorecol/builder-config.yaml

@@ -78,6 +78,7 @@ replaces:
   - go.opentelemetry.io/collector/extension => ../../extension
   - go.opentelemetry.io/collector/extension/auth => ../../extension/auth
   - go.opentelemetry.io/collector/extension/experimental/storage => ../../extension/experimental/storage
+  - go.opentelemetry.io/collector/extension/extensioncapabilities => ../../extension/extensioncapabilities
   - go.opentelemetry.io/collector/extension/memorylimiterextension => ../../extension/memorylimiterextension
   - go.opentelemetry.io/collector/extension/zpagesextension => ../../extension/zpagesextension
   - go.opentelemetry.io/collector/featuregate => ../../featuregate

cmd/otelcorecol/go.mod

@@ -100,6 +100,7 @@ require (
 	go.opentelemetry.io/collector/exporter/exporterprofiles v0.108.1 // indirect
 	go.opentelemetry.io/collector/extension/auth v0.108.1 // indirect
 	go.opentelemetry.io/collector/extension/experimental/storage v0.0.0-20240902085631-cd1f7623fe67 // indirect
+	go.opentelemetry.io/collector/extension/extensioncapabilities v0.108.1 // indirect
 	go.opentelemetry.io/collector/featuregate v1.14.1 // indirect
 	go.opentelemetry.io/collector/internal/globalgates v0.108.1 // indirect
 	go.opentelemetry.io/collector/pdata v1.14.1 // indirect
@@ -223,6 +224,8 @@ replace go.opentelemetry.io/collector/extension/auth => ../../extension/auth
 
 replace go.opentelemetry.io/collector/extension/experimental/storage => ../../extension/experimental/storage
 
+replace go.opentelemetry.io/collector/extension/extensioncapabilities => ../../extension/extensioncapabilities
+
 replace go.opentelemetry.io/collector/extension/memorylimiterextension => ../../extension/memorylimiterextension
 
 replace go.opentelemetry.io/collector/extension/zpagesextension => ../../extension/zpagesextension

extension/extension.go

@@ -8,48 +8,22 @@ import (
 	"fmt"
 
 	"go.opentelemetry.io/collector/component"
-	"go.opentelemetry.io/collector/confmap"
+	"go.opentelemetry.io/collector/extension/internal"
 )
 
 // Extension is the interface for objects hosted by the OpenTelemetry Collector that
 // don't participate directly on data pipelines but provide some functionality
 // to the service, examples: health check endpoint, z-pages, etc.
-type Extension = component.Component
-
-// Dependent is an optional interface that can be implemented by extensions
-// that depend on other extensions and must be started only after their dependencies.
-// See https://github.com/open-telemetry/opentelemetry-collector/pull/8768 for examples.
-type Dependent interface {
-	Extension
-	Dependencies() []component.ID
-}
+type Extension = internal.Extension
 
-// PipelineWatcher is an extra interface for Extension hosted by the OpenTelemetry
-// Collector that is to be implemented by extensions interested in changes to pipeline
-// states. Typically this will be used by extensions that change their behavior if data is
-// being ingested or not, e.g.: a k8s readiness probe.
-type PipelineWatcher interface {
-	// Ready notifies the Extension that all pipelines were built and the
-	// receivers were started, i.e.: the service is ready to receive data
-	// (note that it may already have received data when this method is called).
-	Ready() error
-
-	// NotReady notifies the Extension that all receivers are about to be stopped,
-	// i.e.: pipeline receivers will not accept new data.
-	// This is sent before receivers are stopped, so the Extension can take any
-	// appropriate actions before that happens.
-	NotReady() error
-}
+// Deprecated: [v0.109.0] Use [extensioncapabilities.Dependent] instead.
+type Dependent = internal.Dependent
 
-// ConfigWatcher is an interface that should be implemented by an extension that
-// wishes to be notified of the Collector's effective configuration.
-type ConfigWatcher interface {
-	// NotifyConfig notifies the extension of the Collector's current effective configuration.
-	// The extension owns the `confmap.Conf`. Callers must ensure that it's safe for
-	// extensions to store the `conf` pointer and use it concurrently with any other
-	// instances of `conf`.
-	NotifyConfig(ctx context.Context, conf *confmap.Conf) error
-}
+// Deprecated: [v0.109.0] Use [extensioncapabilities.PipelineWatcher] instead.
+type PipelineWatcher = internal.PipelineWatcher
+
+// Deprecated: [v0.109.0] Use [extensioncapabilities.ConfigWatcher] instead.
+type ConfigWatcher = internal.ConfigWatcher
 
 // ModuleInfo describes the go module for each component.
 type ModuleInfo struct {

extension/extensioncapabilities/Makefile

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

extension/extensioncapabilities/go.mod

@@ -0,0 +1,43 @@
+module go.opentelemetry.io/collector/extension/extensioncapabilities
+
+go 1.22.0
+
+require go.opentelemetry.io/collector/extension v0.108.0
+
+require (
+	github.com/go-viper/mapstructure/v2 v2.1.0 // indirect
+	github.com/gogo/protobuf v1.3.2 // 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 v2.1.1 // indirect
+	github.com/mitchellh/copystructure v1.2.0 // indirect
+	github.com/mitchellh/reflectwalk v1.0.2 // indirect
+	go.opentelemetry.io/collector/component v0.108.1 // indirect
+	go.opentelemetry.io/collector/config/configtelemetry v0.108.1 // indirect
+	go.opentelemetry.io/collector/confmap v1.14.1 // indirect
+	go.opentelemetry.io/collector/pdata v1.14.1 // indirect
+	go.opentelemetry.io/otel v1.29.0 // indirect
+	go.opentelemetry.io/otel/metric v1.29.0 // indirect
+	go.opentelemetry.io/otel/trace v1.29.0 // indirect
+	go.uber.org/multierr v1.11.0 // indirect
+	go.uber.org/zap v1.27.0 // indirect
+	golang.org/x/net v0.27.0 // indirect
+	golang.org/x/sys v0.24.0 // indirect
+	golang.org/x/text v0.16.0 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20240604185151-ef581f913117 // indirect
+	google.golang.org/grpc v1.66.0 // indirect
+	google.golang.org/protobuf v1.34.2 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
+
+replace go.opentelemetry.io/collector/extension => ../
+
+replace go.opentelemetry.io/collector/pdata => ../../pdata
+
+replace go.opentelemetry.io/collector/confmap => ../../confmap
+
+replace go.opentelemetry.io/collector/config/configtelemetry => ../../config/configtelemetry
+
+replace go.opentelemetry.io/collector/component => ../../component
+
+replace go.opentelemetry.io/collector/component/componentstatus => ../../component/componentstatus

extension/extensioncapabilities/interfaces.go

@@ -0,0 +1,25 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+// Package extensioncapabilities provides interfaces that can be implemented by extensions
+// to provide additional capabilities.
+package extensioncapabilities // import "go.opentelemetry.io/collector/extension/extensioncapabilities"
+
+import (
+	"go.opentelemetry.io/collector/extension/internal"
+)
+
+// Dependent is an optional interface that can be implemented by extensions
+// that depend on other extensions and must be started only after their dependencies.
+// See https://github.com/open-telemetry/opentelemetry-collector/pull/8768 for examples.
+type Dependent = internal.Dependent
+
+// PipelineWatcher is an extra interface for Extension hosted by the OpenTelemetry
+// Collector that is to be implemented by extensions interested in changes to pipeline
+// states. Typically this will be used by extensions that change their behavior if data is
+// being ingested or not, e.g.: a k8s readiness probe.
+type PipelineWatcher = internal.PipelineWatcher
+
+// ConfigWatcher is an interface that should be implemented by an extension that
+// wishes to be notified of the Collector's effective configuration.
+type ConfigWatcher = internal.ConfigWatcher