Rough sketch (draft 3) limiter extension and middleware

config/configlimiter/Makefile

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

config/configlimiter/configlimiter.go

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+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+// Package configlimiter implements the configuration settings to
+// apply rate limiting on incoming requests, and allows
+// components to configure rate limiting behavior.
+package configlimiter // import "go.opentelemetry.io/collector/config/configlimiter"
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/extension/extensionlimiter"
+)
+
+var (
+	errLimiterNotFound = errors.New("limiter not found")
+	errNotLimiter      = errors.New("requested extension is not a limiter")
+)
+
+// Limiter defines the rate limiting settings for a component.
+type Limiter struct {
+	// LimiterID specifies the name of the extension to use in order to apply rate limiting.
+	LimiterID component.ID `mapstructure:"limiter,omitempty"`
+}
+
+// GetLimiter attempts to select the appropriate extensionlimiter.Limiter from the list of extensions,
+// based on the requested extension name. If a limiter is not found, an error is returned.
+func (l Limiter) GetRateLimiter(_ context.Context, extensions map[component.ID]component.Component) (extensionlimiter.RateLimiter, error) {
+	if ext, found := extensions[l.LimiterID]; found {
+		if limiter, ok := ext.(extensionlimiter.RateLimiter); ok {
+			return limiter, nil
+		}
+		return nil, errNotLimiter
+	}
+
+	return nil, fmt.Errorf("failed to resolve limiter %q: %w", l.LimiterID, errLimiterNotFound)
+}
+
+// GetResourceLimiter attempts to select the appropriate extensionlimiter.ResourceLimiter from the list of extensions,
+// based on the requested extension name. If a limiter is not found, an error is returned.
+func (l Limiter) GetResourceLimiter(_ context.Context, extensions map[component.ID]component.Component) (extensionlimiter.ResourceLimiter, error) {
+	if ext, found := extensions[l.LimiterID]; found {
+		if limiter, ok := ext.(extensionlimiter.ResourceLimiter); ok {
+			return limiter, nil
+		}
+		return nil, errNotLimiter
+	}
+
+	return nil, fmt.Errorf("failed to resolve resource limiter %q: %w", l.LimiterID, errLimiterNotFound)
+}

config/configlimiter/go.mod

@@ -0,0 +1,29 @@
+module go.opentelemetry.io/collector/config/configlimiterg
+
+go 1.23.0
+
+require (
+	go.opentelemetry.io/collector/component v1.28.1
+	go.opentelemetry.io/collector/extension/extensionlimiter v0.0.0-00010101000000-000000000000
+)
+
+require (
+	github.com/gogo/protobuf v1.3.2 // indirect
+	go.opentelemetry.io/collector/pdata v1.28.1 // indirect
+	go.opentelemetry.io/otel v1.35.0 // indirect
+	go.opentelemetry.io/otel/metric v1.35.0 // indirect
+	go.opentelemetry.io/otel/sdk/metric v1.35.0 // indirect
+	go.opentelemetry.io/otel/trace v1.35.0 // indirect
+	go.uber.org/multierr v1.11.0 // indirect
+	go.uber.org/zap v1.27.0 // indirect
+	golang.org/x/net v0.37.0 // indirect
+	golang.org/x/sys v0.31.0 // indirect
+	golang.org/x/text v0.23.0 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20250115164207-1a7da9e5054f // indirect
+	google.golang.org/grpc v1.71.0 // indirect
+	google.golang.org/protobuf v1.36.5 // indirect
+)
+
+replace go.opentelemetry.io/collector/component => ../../component
+
+replace go.opentelemetry.io/collector/extension/extensionlimiter => ../../extension/extensionlimiter

config/configmiddleware/Makefile

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

config/configmiddleware/configmiddleware.go

@@ -0,0 +1,83 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+// Package configmiddleware implements the configuration settings to
+// apply middleware processing on telemetry data, and allows
+// components to configure middleware behavior.
+package configmiddleware // import "go.opentelemetry.io/collector/config/configmiddleware"
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/extension/extensionmiddleware"
+)
+
+var (
+	errMiddlewareNotFound = errors.New("middleware not found")
+	errNotMiddleware      = errors.New("requested extension is not a middleware")
+	errNotHTTPServer      = errors.New("requested extension is not an HTTP server middleware")
+	errNotGRPCServer      = errors.New("requested extension is not a gRPC server middleware")
+	errNotHTTPClient      = errors.New("requested extension is not an HTTP client middleware")
+	errNotGRPCClient      = errors.New("requested extension is not a gRPC client middleware")
+)
+
+// Middleware defines the middleware settings for a component.
+type Middleware struct {
+	// MiddlewareID specifies the name of the extension to use in order to apply middleware processing.
+	MiddlewareID component.ID `mapstructure:"middleware,omitempty"`
+}
+
+// GetHTTPServerMiddleware attempts to select the appropriate extensionmiddleware.HTTPServer from the list of extensions,
+// based on the requested extension name. If a middleware is not found, an error is returned.
+func (m Middleware) GetHTTPServerMiddleware(_ context.Context, extensions map[component.ID]component.Component) (extensionmiddleware.HTTPServer, error) {
+	if ext, found := extensions[m.MiddlewareID]; found {
+		if server, ok := ext.(extensionmiddleware.HTTPServer); ok {
+			return server, nil
+		}
+		return nil, errNotHTTPServer
+	}
+
+	return nil, fmt.Errorf("failed to resolve middleware %q: %w", m.MiddlewareID, errMiddlewareNotFound)
+}
+
+// GetGRPCServerMiddleware attempts to select the appropriate extensionmiddleware.GRPCServer from the list of extensions,
+// based on the requested extension name. If a middleware is not found, an error is returned.
+func (m Middleware) GetGRPCServerMiddleware(_ context.Context, extensions map[component.ID]component.Component) (extensionmiddleware.GRPCServer, error) {
+	if ext, found := extensions[m.MiddlewareID]; found {
+		if server, ok := ext.(extensionmiddleware.GRPCServer); ok {
+			return server, nil
+		}
+		return nil, errNotGRPCServer
+	}
+
+	return nil, fmt.Errorf("failed to resolve middleware %q: %w", m.MiddlewareID, errMiddlewareNotFound)
+}
+
+// GetHTTPClientMiddleware attempts to select the appropriate extensionmiddleware.HTTPClient from the list of extensions,
+// based on the component id of the extension. If a middleware is not found, an error is returned.
+// This should be only used by HTTP clients.
+func (m Middleware) GetHTTPClientMiddleware(_ context.Context, extensions map[component.ID]component.Component) (extensionmiddleware.HTTPClient, error) {
+	if ext, found := extensions[m.MiddlewareID]; found {
+		if client, ok := ext.(extensionmiddleware.HTTPClient); ok {
+			return client, nil
+		}
+		return nil, errNotHTTPClient
+	}
+	return nil, fmt.Errorf("failed to resolve middleware %q: %w", m.MiddlewareID, errMiddlewareNotFound)
+}
+
+// GetGRPCClientMiddleware attempts to select the appropriate extensionmiddleware.GRPCClient from the list of extensions,
+// based on the component id of the extension. If a middleware is not found, an error is returned.
+// This should be only used by gRPC clients.
+func (m Middleware) GetGRPCClientMiddleware(_ context.Context, extensions map[component.ID]component.Component) (extensionmiddleware.GRPCClient, error) {
+	if ext, found := extensions[m.MiddlewareID]; found {
+		if client, ok := ext.(extensionmiddleware.GRPCClient); ok {
+			return client, nil
+		}
+		return nil, errNotGRPCClient
+	}
+	return nil, fmt.Errorf("failed to resolve middleware %q: %w", m.MiddlewareID, errMiddlewareNotFound)
+}

config/configmiddleware/go.mod

@@ -0,0 +1,30 @@
+module go.opentelemetry.io/collector/config/configlimiter
+
+go 1.23.0
+
+replace go.opentelemetry.io/collector/component => ../../component
+
+replace go.opentelemetry.io/collector/extension/extensionmiddleware => ../../extension/extensionmiddleware
+
+//replace go.opentelemetry.io/collector/extension/extensionmiddleware/extensionmiddlewaretest => ../../extension/extensionmiddleware/extensionmiddlewaretest
+
+require (
+	go.opentelemetry.io/collector/component v0.0.0-00010101000000-000000000000
+	go.opentelemetry.io/collector/extension/extensionmiddleware v0.0.0-00010101000000-000000000000
+)
+
+require (
+	github.com/gogo/protobuf v1.3.2 // indirect
+	go.opentelemetry.io/collector/pdata v1.28.1 // indirect
+	go.opentelemetry.io/otel v1.35.0 // indirect
+	go.opentelemetry.io/otel/metric v1.35.0 // indirect
+	go.opentelemetry.io/otel/trace v1.35.0 // indirect
+	go.uber.org/multierr v1.11.0 // indirect
+	go.uber.org/zap v1.27.0 // indirect
+	golang.org/x/net v0.37.0 // indirect
+	golang.org/x/sys v0.31.0 // indirect
+	golang.org/x/text v0.23.0 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20250115164207-1a7da9e5054f // indirect
+	google.golang.org/grpc v1.71.0 // indirect
+	google.golang.org/protobuf v1.36.5 // indirect
+)