add help

Makefile

@@ -1,4 +1,4 @@
-.PHONY: clean test
+.PHONY: clean test gen
 
 aws-sdk-client-go: go.* *.go gen
 	go build -o $@ cmd/aws-sdk-client-go/main.go
@@ -13,9 +13,3 @@ gen:
 
 test:
 	go test -v ./...
-
-install:
-	go install github.com/fujiwara/aws-sdk-client-go/cmd/aws-sdk-client-go
-
-dist:
-	goreleaser build --snapshot --rm-dist

README.md

@@ -1,8 +1,8 @@
 # aws-sdk-client-go
 
-aws-sdk-client-go is a Go client for AWS SDK services.
+aws-sdk-client-go is a Go client CLI for AWS SDK services.
 
-This client is auto generated from the AWS SDK Go service client.
+This CLI is auto generated from the AWS SDK Go v2 service client.
 
 ## Motivation
 
@@ -28,7 +28,7 @@ services:
 
 Keys of `services` are AWS service names (`github.com/aws/aws-sdk-go-v2/service/*`), and values are method names of the service client. If you don't specify the method names, all methods of the service client are generated.
 
-To build the client, run the following commands:
+To build the client, run the following commands (or simply run `make`):
 
 ```console
 $ go generate ./cmd/aws-sdk-client-gen .
@@ -72,6 +72,14 @@ $ aws-sdk-client-go ecs DescribeClusters '{"Cluster":"default"}'
 
 The third argument is JSON input for the method. If the method does not require input, you can omit the third argument (implicitly `{}` passed).
 
+#### Show help
+
+aws-sdk-client-go is a simple wrapper of the AWS SDK Go v2 service client. Its usage is the same as that of the AWS SDK Go v2.
+
+```console
+$ aws-sdk-client-go ecs DescribeClusters help
+See https://pkg.go.dev/github.com/aws/aws-sdk-go-v2/service/ecs#Client.DescribeClusters
+```
 
 ## LICENSE
 

cmd/aws-sdk-client-gen/main.go

@@ -25,6 +25,8 @@ func gen(pkgName string, clientType reflect.Type, genNames []string) error {
 		"context"
 		"encoding/json"
 		"fmt"
+
+		"github.com/aws/aws-sdk-go-v2/aws"
 		"github.com/aws/aws-sdk-go-v2/service/%s"
 	)
 	`, pkgName)
@@ -44,40 +46,30 @@ func gen(pkgName string, clientType reflect.Type, genNames []string) error {
 		}
 		methodNames = append(methodNames, method.Name)
 		log.Printf("generating %s_%s", pkgName, method.Name)
-		fmt.Fprintf(buf, `func %s_%s(ctx context.Context, b json.RawMessage) (any, error) {
+		fmt.Fprintf(buf, `func %s_%s(ctx context.Context, awsCfg aws.Config, b json.RawMessage) (any, error) {
 			svc := %s.NewFromConfig(awsCfg)
 			var in %s
 			if err := json.Unmarshal(b, &in); err != nil {
 				return nil, fmt.Errorf("failed to unmarshal request: %%w", err)
 			}
-			if out, err := svc.%s(ctx, &in); err != nil {
-				return nil, fmt.Errorf("failed to call %s: %%w", err)
-			} else {
-				return out, nil
-			}
+			return svc.%s(ctx, &in)
 		}
 		`,
 			pkgName,
 			method.Name,
 			pkgName,
 			strings.TrimPrefix(params[2], "*"), // (receiver, context.Context, *Request, ...)
 			method.Name,
-			method.Name,
 		)
 		fmt.Fprintln(buf)
 	}
 	fmt.Fprintln(buf, `func init() {`)
 	for _, name := range methodNames {
-		fmt.Fprintf(buf, `clientMethods["%s_%s"] = %s_%s
-		`, pkgName, name, pkgName, name)
+		fmt.Fprintf(buf, "	clientMethods[\"%s#Client.%s\"] = %s_%s\n", pkgName, name, pkgName, name)
 	}
 	fmt.Fprintln(buf, "}")
-	f, err := os.OpenFile(pkgName+"_gen.go", os.O_CREATE|os.O_WRONLY, 0644)
-	if err != nil {
-		return err
-	}
-	defer f.Close()
-	if _, err := f.WriteString(buf.String()); err != nil {
+
+	if err := os.WriteFile(pkgName+"_gen.go", []byte(buf.String()), 0644); err != nil {
 		return err
 	}
 	log.Printf("generated %s_gen.go", pkgName)

main.go

@@ -13,13 +13,11 @@ import (
 	"github.com/aws/aws-sdk-go-v2/config"
 )
 
-var awsCfg aws.Config
-
-var clientMethods = make(map[string]func(context.Context, json.RawMessage) (any, error))
+var clientMethods = make(map[string]func(context.Context, aws.Config, json.RawMessage) (any, error))
 
 func Run(ctx context.Context) error {
 	var err error
-	awsCfg, err = config.LoadDefaultConfig(ctx)
+	awsCfg, err := config.LoadDefaultConfig(ctx)
 	if err != nil {
 		return err
 	}
@@ -33,23 +31,28 @@ func Run(ctx context.Context) error {
 		pkgName := os.Args[1]
 		methodName := os.Args[2]
 		input := json.RawMessage(`{}`)
-		return dispatchMethod(ctx, pkgName, methodName, input)
+		return dispatchMethod(ctx, awsCfg, pkgName, methodName, input)
 	case 4:
 		pkgName := os.Args[1]
 		methodName := os.Args[2]
 		input := json.RawMessage(os.Args[3])
-		return dispatchMethod(ctx, pkgName, methodName, input)
+		return dispatchMethod(ctx, awsCfg, pkgName, methodName, input)
 	default:
 		return fmt.Errorf("too many args")
 	}
 }
 
-func dispatchMethod(ctx context.Context, pkgName, methodName string, in json.RawMessage) error {
-	fn := clientMethods[pkgName+"_"+methodName]
+func dispatchMethod(ctx context.Context, awsCfg aws.Config, pkgName, methodName string, in json.RawMessage) error {
+	key := buildKey(pkgName, methodName)
+	if bytes.Equal(in, []byte(`help`)) {
+		fmt.Printf("See https://pkg.go.dev/github.com/aws/aws-sdk-go-v2/service/%s\n", key)
+		return nil
+	}
+	fn := clientMethods[key]
 	if fn == nil {
-		return fmt.Errorf("unknown method %s of %s", methodName, pkgName)
+		return fmt.Errorf("unknown function %s", key)
 	}
-	out, err := fn(ctx, in)
+	out, err := fn(ctx, awsCfg, in)
 	if err != nil {
 		return err
 	}
@@ -67,8 +70,9 @@ func dispatchMethod(ctx context.Context, pkgName, methodName string, in json.Raw
 func listMethods(pkgName string) error {
 	methods := make([]string, 0)
 	for name := range clientMethods {
-		if strings.HasPrefix(name, pkgName+"_") {
-			methods = append(methods, strings.TrimPrefix(name, pkgName+"_"))
+		service, method := parseKey(name)
+		if service == pkgName {
+			methods = append(methods, method)
 		}
 	}
 	sort.Strings(methods)
@@ -81,7 +85,8 @@ func listMethods(pkgName string) error {
 func listServices() error {
 	services := make(map[string]struct{})
 	for name := range clientMethods {
-		services[strings.Split(name, "_")[0]] = struct{}{}
+		service, _ := parseKey(name)
+		services[service] = struct{}{}
 	}
 	names := make([]string, 0)
 	for name := range services {
@@ -94,4 +99,15 @@ func listServices() error {
 	return nil
 }
 
+func parseKey(key string) (string, string) {
+	parts := strings.Split(key, "#")
+	service := parts[0]
+	method := strings.SplitN(parts[1], ".", 2)[1]
+	return service, method
+}
+
+func buildKey(service, method string) string {
+	return fmt.Sprintf("%s#Client.%s", service, method)
+}
+
 //go:generate go run cmd/aws-sdk-client-gen/main.go cmd/aws-sdk-client-gen/gen.go