[confighttp, configgrpc] Replace host parameter by map of extensions (#14190)

#### Description

Alternative to #14162, where we make the map of extensions a mandatory
positional parameter to replace `host` instead of an option.

#### Link to tracking issue
Fixes #13640

#### Testing
Existing tests make extensive use of the modified functions

#### Documentation
Added line in ToServer/ToClient(Conn) documentation describing the
intended use of the extensions parameter.

---------

Co-authored-by: Pablo Baeyens <[email protected]>
Co-authored-by: Pablo Baeyens <[email protected]>

Author: jade-guiton-dd

.chloggen/no-host-in-configgrpc.yaml

@@ -0,0 +1,29 @@
+# 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. otlpreceiver)
+component: pkg/config/configgrpc
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Replace `component.Host` parameter of ToServer/ToClientConn by map of extensions
+
+# One or more tracking issues or pull requests related to the change
+issues: [13640]
+
+# (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: |
+  Components must now pass the map obtained from the host's `GetExtensions` method
+  instead of the host itself.
+  
+  Nil may be used in tests where no middleware or authentication extensions are used.
+
+# 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/no-host-in-confighttp.yaml

@@ -0,0 +1,29 @@
+# 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. otlpreceiver)
+component: pkg/config/confighttp
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Replace `component.Host` parameter of ToServer/ToClient by map of extensions
+
+# One or more tracking issues or pull requests related to the change
+issues: [13640]
+
+# (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: |
+  Components must now pass the map obtained from the host's `GetExtensions` method
+  instead of the host itself.
+  
+  Nil may be used in tests where no middleware or authentication extensions are used.
+
+# 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]

component/componenttest/nop_host.go

@@ -19,7 +19,7 @@ func NewNopHost() component.Host {
 	return &nopHost{}
 }
 
-// GetExtensions returns a `nil` extensions map.
+// GetExtensions returns an empty extensions map.
 func (nh *nopHost) GetExtensions() map[component.ID]component.Component {
-	return nil
+	return map[component.ID]component.Component{}
 }

component/componenttest/nop_host_test.go

@@ -15,5 +15,7 @@ func TestNewNopHost(t *testing.T) {
 	require.NotNil(t, nh)
 	require.IsType(t, &nopHost{}, nh)
 
-	assert.Nil(t, nh.GetExtensions())
+	extensions := nh.GetExtensions()
+	assert.NotNil(t, extensions)
+	assert.Empty(t, extensions)
 }

component/host.go

@@ -17,5 +17,7 @@ type Host interface {
 	//
 	// GetExtensions can be called by the component anytime after Component.Start() begins and
 	// until Component.Shutdown() ends.
+	//
+	// The returned map should only be nil if the host does not support extensions at all.
 	GetExtensions() map[ID]Component
 }

config/configgrpc/client_middleware_test.go

@@ -124,11 +124,8 @@ func TestClientMiddlewareOrdering(t *testing.T) {
 		},
 	}
 
-	// Create a test host with our mock extensions
-	host := &mockHost{ext: mockExt}
-
 	// Send a request using the client with middleware
-	resp, err := sendTestRequestWithHost(t, clientConfig, host)
+	resp, err := sendTestRequestWithExtensions(t, clientConfig, mockExt)
 	require.NoError(t, err)
 	assert.NotNil(t, resp)
 
@@ -147,16 +144,14 @@ func TestClientMiddlewareOrdering(t *testing.T) {
 // specifically related to middleware resolution and API calls.
 func TestClientMiddlewareToClientErrors(t *testing.T) {
 	tests := []struct {
-		name    string
-		host    component.Host
-		config  ClientConfig
-		errText string
+		name       string
+		extensions map[component.ID]component.Component
+		config     ClientConfig
+		errText    string
 	}{
 		{
-			name: "extension_not_found",
-			host: &mockHost{
-				ext: map[component.ID]component.Component{},
-			},
+			name:       "extension_not_found",
+			extensions: map[component.ID]component.Component{},
 			config: ClientConfig{
 				Endpoint: "localhost:1234",
 				TLS: configtls.ClientConfig{
@@ -172,10 +167,8 @@ func TestClientMiddlewareToClientErrors(t *testing.T) {
 		},
 		{
 			name: "get_client_options_fails",
-			host: &mockHost{
-				ext: map[component.ID]component.Component{
-					component.MustNewID("errormw"): extensionmiddlewaretest.NewErr(errors.New("get options failed")),
-				},
+			extensions: map[component.ID]component.Component{
+				component.MustNewID("errormw"): extensionmiddlewaretest.NewErr(errors.New("get options failed")),
 			},
 			config: ClientConfig{
 				Endpoint: "localhost:1234",
@@ -195,7 +188,7 @@ func TestClientMiddlewareToClientErrors(t *testing.T) {
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {
 			// Test creating the client with middleware errors
-			_, err := tc.config.ToClientConn(context.Background(), tc.host, componenttest.NewNopTelemetrySettings())
+			_, err := tc.config.ToClientConn(context.Background(), tc.extensions, componenttest.NewNopTelemetrySettings())
 			require.Error(t, err)
 			assert.Contains(t, err.Error(), tc.errText)
 		})

config/configgrpc/configgrpc.go

@@ -272,13 +272,17 @@ func (grpcDialOptionWrapper) isToClientConnOption() {}
 // a non-blocking dial (the function won't wait for connections to be
 // established, and connecting happens in the background). To make it a blocking
 // dial, use the WithGrpcDialOption(grpc.WithBlock()) option.
+//
+// To allow the configuration to reference middleware or authentication extensions,
+// the `extensions` argument should be the output of `host.GetExtensions()`.
+// It may also be `nil` in tests where no such extension is expected to be used.
 func (cc *ClientConfig) ToClientConn(
 	ctx context.Context,
-	host component.Host,
+	extensions map[component.ID]component.Component,
 	settings component.TelemetrySettings,
 	extraOpts ...ToClientConnOption,
 ) (*grpc.ClientConn, error) {
-	grpcOpts, err := cc.getGrpcDialOptions(ctx, host, settings, extraOpts)
+	grpcOpts, err := cc.getGrpcDialOptions(ctx, extensions, settings, extraOpts)
 	if err != nil {
 		return nil, err
 	}
@@ -299,7 +303,7 @@ func (cc *ClientConfig) addHeadersIfAbsent(ctx context.Context) context.Context
 
 func (cc *ClientConfig) getGrpcDialOptions(
 	ctx context.Context,
-	host component.Host,
+	extensions map[component.ID]component.Component,
 	settings component.TelemetrySettings,
 	extraOpts []ToClientConnOption,
 ) ([]grpc.DialOption, error) {
@@ -343,11 +347,11 @@ func (cc *ClientConfig) getGrpcDialOptions(
 	}
 
 	if cc.Auth.HasValue() {
-		if host.GetExtensions() == nil {
-			return nil, errors.New("no extensions configuration available")
+		if extensions == nil {
+			return nil, errors.New("authentication was configured but this component or its host does not support extensions")
 		}
 
-		grpcAuthenticator, cerr := cc.Auth.Get().GetGRPCClientAuthenticator(ctx, host.GetExtensions())
+		grpcAuthenticator, cerr := cc.Auth.Get().GetGRPCClientAuthenticator(ctx, extensions)
 		if cerr != nil {
 			return nil, cerr
 		}
@@ -388,8 +392,11 @@ func (cc *ClientConfig) getGrpcDialOptions(
 	}
 
 	// Apply middleware options. Note: OpenTelemetry could be registered as an extension.
+	if len(cc.Middlewares) > 0 && extensions == nil {
+		return nil, errors.New("middlewares were configured but this component or its host does not support extensions")
+	}
 	for _, middleware := range cc.Middlewares {
-		middlewareOptions, err := middleware.GetGRPCClientOptions(ctx, host.GetExtensions())
+		middlewareOptions, err := middleware.GetGRPCClientOptions(ctx, extensions)
 		if err != nil {
 			return nil, fmt.Errorf("failed to get gRPC client options from middleware: %w", err)
 		}
@@ -437,13 +444,17 @@ func WithGrpcServerOption(opt grpc.ServerOption) ToServerOption {
 func (grpcServerOptionWrapper) isToServerOption() {}
 
 // ToServer returns a [grpc.Server] for the configuration.
+//
+// To allow the configuration to reference middleware or authentication extensions,
+// the `extensions` argument should be the output of `host.GetExtensions()`.
+// It may also be `nil` in tests where no such extension is expected to be used.
 func (sc *ServerConfig) ToServer(
 	ctx context.Context,
-	host component.Host,
+	extensions map[component.ID]component.Component,
 	settings component.TelemetrySettings,
 	extraOpts ...ToServerOption,
 ) (*grpc.Server, error) {
-	grpcOpts, err := sc.getGrpcServerOptions(ctx, host, settings, extraOpts)
+	grpcOpts, err := sc.getGrpcServerOptions(ctx, extensions, settings, extraOpts)
 	if err != nil {
 		return nil, err
 	}
@@ -452,7 +463,7 @@ func (sc *ServerConfig) ToServer(
 
 func (sc *ServerConfig) getGrpcServerOptions(
 	ctx context.Context,
-	host component.Host,
+	extensions map[component.ID]component.Component,
 	settings component.TelemetrySettings,
 	extraOpts []ToServerOption,
 ) ([]grpc.ServerOption, error) {
@@ -515,7 +526,7 @@ func (sc *ServerConfig) getGrpcServerOptions(
 	var sInterceptors []grpc.StreamServerInterceptor
 
 	if sc.Auth.HasValue() {
-		authenticator, err := sc.Auth.Get().GetServerAuthenticator(ctx, host.GetExtensions())
+		authenticator, err := sc.Auth.Get().GetServerAuthenticator(ctx, extensions)
 		if err != nil {
 			return nil, err
 		}
@@ -539,7 +550,7 @@ func (sc *ServerConfig) getGrpcServerOptions(
 
 	// Apply middleware options. Note: OpenTelemetry could be registered as an extension.
 	for _, middleware := range sc.Middlewares {
-		middlewareOptions, err := middleware.GetGRPCServerOptions(ctx, host.GetExtensions())
+		middlewareOptions, err := middleware.GetGRPCServerOptions(ctx, extensions)
 		if err != nil {
 			return nil, fmt.Errorf("failed to get gRPC server options from middleware: %w", err)
 		}