How to use Go Kit?

gistfile1.txt

# Go kit Introduction

Go kit is a library for building microservices in Go. It offers tools that facilitate the implementation of microservices in a robust and scalable manner.

## Getting Started

### 1. Setup

Ensure Go is installed. Install the Go kit library:

```bash
go get github.com/go-kit/kit
```

### 2. Create a Service

Organize your functionality around a "service". Here's a basic `StringService`:

```go
type StringService interface {
	Uppercase(string) (string, error)
}

type stringService struct{}

func (stringService) Uppercase(s string) (string, error) {
	if s == "" {
		return "", errors.New("empty string")
	}
	return strings.ToUpper(s), nil
}
```

### 3. Define Endpoints

For each method of our service, define an endpoint:

```go
type Endpoints struct {
	UppercaseEndpoint endpoint.Endpoint
}

func MakeUppercaseEndpoint(s StringService) endpoint.Endpoint {
	return func(ctx context.Context, request interface{}) (interface{}, error) {
		req := request.(uppercaseRequest)
		v, err := s.Uppercase(req.S)
		return uppercaseResponse{v, err}, nil
	}
}

type uppercaseRequest struct {
	S string `json:"s"`
}

type uppercaseResponse struct {
	V   string `json:"v"`
	Err error  `json:"err,omitempty"`
}
```

### 4. Transport

Separate the transport logic (HTTP, gRPC, etc.) from your business logic:

```go
func MakeHTTPHandler(s StringService) http.Handler {
	r := mux.NewRouter()

	r.Methods("POST").Path("/uppercase").Handler(httptransport.NewServer(
		MakeUppercaseEndpoint(s),
		decodeUppercaseRequest,
		encodeResponse,
	))

	return r
}

func decodeUppercaseRequest(_ context.Context, r *http.Request) (interface{}, error) {
	var request uppercaseRequest
	if err := json.NewDecoder(r.Body).Decode(&request); err != nil {
		return nil, err
	}
	return request, nil
}

func encodeResponse(_ context.Context, w http.ResponseWriter, response interface{}) error {
	return json.NewEncoder(w).Encode(response)
}
```

### 5. Running the Service

Run your service with the following:

```go
func main() {
	svc := stringService{}
	handler := MakeHTTPHandler(svc)
	http.ListenAndServe(":8080", handler)
}
```

Visit `http://localhost:8080/uppercase` with a POST request containing JSON like `{"s": "hello"}` to test.

---

For a more comprehensive dive into Go kit, refer to the [official documentation](https://gokit.io/).