Initial interceptors implementation (#3616)

* Merge v3

* Remove Twitter badge

* Improve generated comments

* Add support for interceptors in generated examples

* Finalize initial interceptor implementation

* Fix tests

codegen/cli/cli.go

@@ -34,6 +34,8 @@ type (
 		// PkgName is the service HTTP client package import name,
 		// e.g. "storagec".
 		PkgName string
+		// Interceptors contains the data for client interceptors if any.
+		Interceptors *InterceptorData
 	}
 
 	// SubcommandData contains the data needed to render a sub-command.
@@ -58,6 +60,14 @@ type (
 		Example string
 	}
 
+	// InterceptorData contains the data needed to generate interceptor code.
+	InterceptorData struct {
+		// VarName is the name of the interceptor variable.
+		VarName string
+		// PkgName is the package name containing the interceptor type.
+		PkgName string
+	}
+
 	// FlagData contains the data needed to render a command-line flag.
 	FlagData struct {
 		// Name is the name of the flag, e.g. "list-vintage"
@@ -151,11 +161,21 @@ func BuildCommandData(data *service.Data) *CommandData {
 	if description == "" {
 		description = fmt.Sprintf("Make requests to the %q service", data.Name)
 	}
+
+	var interceptors *InterceptorData
+	if len(data.ClientInterceptors) > 0 {
+		interceptors = &InterceptorData{
+			VarName: "inter",
+			PkgName: data.PkgName,
+		}
+	}
+
 	return &CommandData{
-		Name:        codegen.KebabCase(data.Name),
-		VarName:     codegen.Goify(data.Name, false),
-		Description: description,
-		PkgName:     data.PkgName + "c",
+		Name:         codegen.KebabCase(data.Name),
+		VarName:      codegen.Goify(data.Name, false),
+		Description:  description,
+		PkgName:      data.PkgName + "c",
+		Interceptors: interceptors,
 	}
 }
 
@@ -682,7 +702,8 @@ const parseFlagsT = `var (
 `
 
 // input: commandData
-const commandUsageT = `{{ printf "%sUsage displays the usage of the %s command and its subcommands." .Name .Name | comment }}
+const commandUsageT = `
+{{ printf "%sUsage displays the usage of the %s command and its subcommands." .VarName .Name | comment }}
 func {{ .VarName }}Usage() {
 	fmt.Fprintf(os.Stderr, ` + "`" + `{{ printDescription .Description }}
 Usage:

codegen/example/example_server.go

@@ -50,14 +50,17 @@ func exampleSvrMain(genpkg string, root *expr.RootExpr, svr *expr.ServerExpr) *c
 	// Iterate through services listed in the server expression.
 	svcData := make([]*service.Data, len(svr.Services))
 	scope := codegen.NewNameScope()
+	hasInterceptors := false
 	for i, svc := range svr.Services {
 		sd := service.Services.Get(svc)
 		svcData[i] = sd
 		specs = append(specs, &codegen.ImportSpec{
 			Path: path.Join(genpkg, sd.PathName),
-			Name: scope.Unique(sd.PkgName),
+			Name: scope.Unique(sd.PkgName, "svc"),
 		})
+		hasInterceptors = hasInterceptors || len(sd.ServerInterceptors) > 0
 	}
+	interPkg := scope.Unique("interceptors", "ex")
 
 	var (
 		rootPath string
@@ -73,6 +76,9 @@ func exampleSvrMain(genpkg string, root *expr.RootExpr, svr *expr.ServerExpr) *c
 		apiPkg = scope.Unique(strings.ToLower(codegen.Goify(root.API.Name, false)), "api")
 	}
 	specs = append(specs, &codegen.ImportSpec{Path: rootPath, Name: apiPkg})
+	if hasInterceptors {
+		specs = append(specs, &codegen.ImportSpec{Path: path.Join(rootPath, "interceptors"), Name: interPkg})
+	}
 
 	sections := []*codegen.SectionTemplate{
 		codegen.Header("", "main", specs),
@@ -101,6 +107,18 @@ func exampleSvrMain(genpkg string, root *expr.RootExpr, svr *expr.ServerExpr) *c
 			FuncMap: map[string]any{
 				"mustInitServices": mustInitServices,
 			},
+		}, {
+			Name:   "server-main-interceptors",
+			Source: readTemplate("server_interceptors"),
+			Data: map[string]any{
+				"APIPkg":          apiPkg,
+				"InterPkg":        interPkg,
+				"Services":        svcData,
+				"HasInterceptors": hasInterceptors,
+			},
+			FuncMap: map[string]any{
+				"mustInitServices": mustInitServices,
+			},
 		}, {
 			Name:   "server-main-endpoints",
 			Source: readTemplate("server_endpoints"),

codegen/example/templates/server_endpoints.go.tpl

@@ -11,7 +11,7 @@
 	{
 	{{- range .Services }}
 		{{- if .Methods }}
-			{{ .VarName }}Endpoints = {{ .PkgName }}.NewEndpoints({{ .VarName }}Svc)
+			{{ .VarName }}Endpoints = {{ .PkgName }}.NewEndpoints({{ .VarName }}Svc{{ if .ServerInterceptors }}, {{ .VarName }}Interceptors{{ end }})
 			{{ .VarName }}Endpoints.Use(debug.LogPayloads())
 			{{ .VarName }}Endpoints.Use(log.Endpoint)
 		{{- end }}

codegen/example/templates/server_interceptors.go.tpl

@@ -0,0 +1,19 @@
+{{- if mustInitServices .Services }}
+	{{- if .HasInterceptors }}
+	{{ comment "Initialize the interceptors." }}
+	var (
+		{{- range .Services }}
+			{{- if and .Methods .ServerInterceptors }}
+		{{ .VarName }}Interceptors {{ .PkgName }}.ServerInterceptors
+			{{- end }}
+		{{- end }}
+	)
+	{
+	{{- range .Services }}
+		{{- if and .Methods .ServerInterceptors }}
+		{{ .VarName }}Interceptors = {{ $.InterPkg }}.New{{ .StructName }}ServerInterceptors()
+		{{- end }}
+	{{- end }}
+	}
+	{{- end }}
+{{- end }}

codegen/generator/example.go

@@ -25,6 +25,11 @@ func Example(genpkg string, roots []eval.Root) ([]*codegen.File, error) {
 			files = append(files, fs...)
 		}
 
+		// example interceptors implementation
+		if fs := service.ExampleInterceptorsFiles(genpkg, r); len(fs) != 0 {
+			files = append(files, fs...)
+		}
+
 		// server main
 		if fs := example.ServerFiles(genpkg, r); len(fs) != 0 {
 			files = append(files, fs...)
@@ -54,6 +59,8 @@ func Example(genpkg string, roots []eval.Root) ([]*codegen.File, error) {
 				files = append(files, fs...)
 			}
 		}
+
+		// Add imports defined via struct:field:type
 		for _, f := range files {
 			if len(f.SectionTemplates) > 0 {
 				for _, s := range r.Services {

codegen/service/client.go

@@ -15,7 +15,7 @@ const (
 // ClientFile returns the client file for the given service.
 func ClientFile(_ string, service *expr.ServiceExpr) *codegen.File {
 	svc := Services.Get(service.Name)
-	data := endpointData(service)
+	data := endpointData(svc)
 	path := filepath.Join(codegen.Gendir, svc.PathName, "client.go")
 	var (
 		sections []*codegen.SectionTemplate

codegen/service/client_test.go

@@ -32,6 +32,7 @@ func TestClient(t *testing.T) {
 		{"client-streaming-payload-no-result", testdata.StreamingPayloadNoResultMethodDSL, testdata.StreamingPayloadNoResultMethodClient},
 		{"client-bidirectional-streaming", testdata.BidirectionalStreamingMethodDSL, testdata.BidirectionalStreamingMethodClient},
 		{"client-bidirectional-streaming-no-payload", testdata.BidirectionalStreamingNoPayloadMethodDSL, testdata.BidirectionalStreamingNoPayloadMethodClient},
+		{"client-interceptor", testdata.EndpointWithClientInterceptorDSL, testdata.InterceptorClient},
 	}
 	for _, c := range cases {
 		t.Run(c.Name, func(t *testing.T) {

codegen/service/convert_test.go

@@ -14,7 +14,6 @@ import (
 	"goa.design/goa/v3/codegen"
 	"goa.design/goa/v3/codegen/service/testdata"
 	"goa.design/goa/v3/dsl"
-	"goa.design/goa/v3/eval"
 	"goa.design/goa/v3/expr"
 )
 
@@ -257,30 +256,7 @@ func TestConvertFile(t *testing.T) {
 	}
 }
 
-// runDSL returns the DSL root resulting from running the given DSL.
-func runDSL(t *testing.T, dsl func()) *expr.RootExpr {
-	// reset all roots and codegen data structures
-	Services = make(ServicesData)
-	eval.Reset()
-	expr.Root = new(expr.RootExpr)
-	expr.GeneratedResultTypes = new(expr.ResultTypesRoot)
-	require.NoError(t, eval.Register(expr.Root))
-	require.NoError(t, eval.Register(expr.GeneratedResultTypes))
-	expr.Root.API = expr.NewAPIExpr("test api", func() {})
-	expr.Root.API.Servers = []*expr.ServerExpr{expr.Root.API.DefaultServer()}
-
-	// run DSL (first pass)
-	require.True(t, eval.Execute(dsl, nil))
-
-	// run DSL (second pass)
-	require.NoError(t, eval.RunDSL())
-
-	// return generated root
-	return expr.Root
-}
-
 // Test fixtures
-
 var obj = &expr.UserTypeExpr{
 	AttributeExpr: &expr.AttributeExpr{
 		Type: &expr.Object{

codegen/service/endpoint.go

@@ -30,6 +30,12 @@ type (
 		// Schemes contains the security schemes types used by the
 		// all the endpoints.
 		Schemes SchemesData
+		// HasServerInterceptors indicates that the service has server-side
+		// interceptors.
+		HasServerInterceptors bool
+		// HasClientInterceptors indicates that the service has client-side
+		// interceptors.
+		HasClientInterceptors bool
 	}
 
 	// EndpointMethodData describes a single endpoint method.
@@ -61,7 +67,7 @@ func EndpointFile(genpkg string, service *expr.ServiceExpr) *codegen.File {
 	svc := Services.Get(service.Name)
 	svcName := svc.PathName
 	path := filepath.Join(codegen.Gendir, svcName, "endpoints.go")
-	data := endpointData(service)
+	data := endpointData(svc)
 	var (
 		sections []*codegen.SectionTemplate
 	)
@@ -128,8 +134,7 @@ func EndpointFile(genpkg string, service *expr.ServiceExpr) *codegen.File {
 	return &codegen.File{Path: path, SectionTemplates: sections}
 }
 
-func endpointData(service *expr.ServiceExpr) *EndpointsData {
-	svc := Services.Get(service.Name)
+func endpointData(svc *Data) *EndpointsData {
 	methods := make([]*EndpointMethodData, len(svc.Methods))
 	names := make([]string, len(svc.Methods))
 	for i, m := range svc.Methods {
@@ -142,16 +147,18 @@ func endpointData(service *expr.ServiceExpr) *EndpointsData {
 		}
 		names[i] = codegen.Goify(m.VarName, false)
 	}
-	desc := fmt.Sprintf("%s wraps the %q service endpoints.", endpointsStructName, service.Name)
+	desc := fmt.Sprintf("%s wraps the %q service endpoints.", endpointsStructName, svc.Name)
 	return &EndpointsData{
-		Name:           service.Name,
-		Description:    desc,
-		VarName:        endpointsStructName,
-		ClientVarName:  clientStructName,
-		ServiceVarName: serviceInterfaceName,
-		ClientInitArgs: strings.Join(names, ", "),
-		Methods:        methods,
-		Schemes:        svc.Schemes,
+		Name:                  svc.Name,
+		Description:           desc,
+		VarName:               endpointsStructName,
+		ClientVarName:         clientStructName,
+		ServiceVarName:        serviceInterfaceName,
+		ClientInitArgs:        strings.Join(names, ", "),
+		Methods:               methods,
+		Schemes:               svc.Schemes,
+		HasServerInterceptors: len(svc.ServerInterceptors) > 0,
+		HasClientInterceptors: len(svc.ClientInterceptors) > 0,
 	}
 }
 

codegen/service/endpoint_test.go

@@ -34,6 +34,8 @@ func TestEndpoint(t *testing.T) {
 		{"endpoint-streaming-payload-no-result", testdata.StreamingPayloadNoResultMethodDSL, testdata.StreamingPayloadNoResultMethodEndpoint},
 		{"endpoint-bidirectional-streaming", testdata.BidirectionalStreamingEndpointDSL, testdata.BidirectionalStreamingMethodEndpoint},
 		{"endpoint-bidirectional-streaming-no-payload", testdata.BidirectionalStreamingNoPayloadMethodDSL, testdata.BidirectionalStreamingNoPayloadMethodEndpoint},
+		{"endpoint-with-server-interceptor", testdata.EndpointWithServerInterceptorDSL, testdata.EndpointWithServerInterceptor},
+		{"endpoint-with-multiple-interceptors", testdata.EndpointWithMultipleInterceptorsDSL, testdata.EndpointWithMultipleInterceptors},
 	}
 	for _, c := range cases {
 		t.Run(c.Name, func(t *testing.T) {

codegen/service/example_interceptors.go

@@ -0,0 +1,86 @@
+package service
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"path/filepath"
+
+	"goa.design/goa/v3/codegen"
+	"goa.design/goa/v3/expr"
+)
+
+// ExampleInterceptorsFiles returns the files for the example server and client interceptors.
+func ExampleInterceptorsFiles(genpkg string, r *expr.RootExpr) []*codegen.File {
+	var fw []*codegen.File
+	for _, svc := range r.Services {
+		if f := exampleInterceptorsFile(genpkg, svc); f != nil {
+			fw = append(fw, f...)
+		}
+	}
+	return fw
+}
+
+// exampleInterceptorsFile returns the example interceptors for the given service.
+func exampleInterceptorsFile(genpkg string, svc *expr.ServiceExpr) []*codegen.File {
+	sdata := Services.Get(svc.Name)
+	data := map[string]any{
+		"ServiceName":        sdata.Name,
+		"StructName":         sdata.StructName,
+		"PkgName":            "interceptors",
+		"ServerInterceptors": sdata.ServerInterceptors,
+		"ClientInterceptors": sdata.ClientInterceptors,
+	}
+
+	var files []*codegen.File
+
+	// Generate server interceptor if needed and file doesn't exist
+	if len(sdata.ServerInterceptors) > 0 {
+		serverPath := filepath.Join("interceptors", sdata.PathName+"_server.go")
+		if _, err := os.Stat(serverPath); os.IsNotExist(err) {
+			files = append(files, &codegen.File{
+				Path: serverPath,
+				SectionTemplates: []*codegen.SectionTemplate{
+					codegen.Header(fmt.Sprintf("%s example server interceptors", sdata.Name), "interceptors", []*codegen.ImportSpec{
+						{Path: "context"},
+						{Path: "fmt"},
+						{Path: "goa.design/clue/log"},
+						codegen.GoaImport(""),
+						{Path: path.Join(genpkg, sdata.PathName), Name: sdata.PkgName},
+					}),
+					{
+						Name:   "exmaple-server-interceptor",
+						Source: readTemplate("example_server_interceptor"),
+						Data:   data,
+					},
+				},
+			})
+		}
+	}
+
+	// Generate client interceptor if needed and file doesn't exist
+	if len(sdata.ClientInterceptors) > 0 {
+		clientPath := filepath.Join("interceptors", sdata.PathName+"_client.go")
+		if _, err := os.Stat(clientPath); os.IsNotExist(err) {
+			files = append(files, &codegen.File{
+				Path: clientPath,
+				SectionTemplates: []*codegen.SectionTemplate{
+					codegen.Header(fmt.Sprintf("%s example client interceptors", sdata.Name), "interceptors", []*codegen.ImportSpec{
+						{Path: "context"},
+						{Path: "fmt"},
+						{Path: "goa.design/clue/log"},
+						codegen.GoaImport(""),
+						{Path: path.Join(genpkg, sdata.PathName), Name: sdata.PkgName},
+					}),
+					{
+						Name:   "example-client-interceptor",
+						Source: readTemplate("example_client_interceptor"),
+						Data:   data,
+					},
+				},
+			})
+		}
+	}
+
+	return files
+}