first commit

.gitignore

@@ -0,0 +1,37 @@
+
+# Created by https://www.toptal.com/developers/gitignore/api/go,visualstudiocode
+# Edit at https://www.toptal.com/developers/gitignore?templates=go,visualstudiocode
+
+### Go ###
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+
+### Go Patch ###
+/vendor/
+/Godeps/
+
+### VisualStudioCode ###
+.vscode/*
+!.vscode/tasks.json
+!.vscode/launch.json
+*.code-workspace
+
+### VisualStudioCode Patch ###
+# Ignore all local history of files
+.history
+.ionide
+
+# End of https://www.toptal.com/developers/gitignore/api/go,visualstudiocode

Dockerfile

@@ -0,0 +1,17 @@
+FROM golang:1.16.5 as builder
+
+WORKDIR /go-microservice/
+
+COPY . .
+
+RUN CGO_ENABLED=0 go build -o microservice /go-microservice/main.go
+
+FROM alpine:latest
+
+WORKDIR /go-microservice
+
+COPY --from=builder /go-microservice/ /go-microservice/
+
+EXPOSE 9090
+
+CMD ./microservice

README.md

@@ -0,0 +1,16 @@
+# Product Catalog API
+
+Blogs for Detailed Tutorial:
+
+* <a href="https://learnai1.home.blog/2021/03/15/microservices-in-go/">Introductory Blog.</a> 
+* <a href="https://learnai1.home.blog/2021/03/18/microservices-in-go-part-2/">Adding More API's.</a>
+* <a href="https://learnai1.home.blog/2021/06/27/authentication-in-go-microservices/">Basic Authentication in Microservices.</a>
+* <a href="https://learnai1.home.blog/2021/07/08/microservices-in-go-part-iv-docker-and-go-microservices/">Docker and Go Microservices.</a>
+* <a href="https://learnai1.home.blog/2021/08/05/https-server-in-go/">HTTPS Server in Go.</a>
+## Run API
+
+``` bash
+go run .\main.go
+```
+
+Use the above command to run API on your local machine on port 9090.

data/data.json

@@ -0,0 +1,30 @@
+[
+    {
+        "id": "e7f31219-7986-11eb-bd65-98fa9b64e75b",
+        "name": "iPhone 12 Pro",
+        "description": "Pro variant of iPhone 12",
+        "price": 100000,
+        "isAvailable": false
+    },
+    {
+        "id": "f82fa5ec-7986-11eb-a8e3-98fa9b64e75b",
+        "name": "iPhone 12 Pro Max",
+        "description": "Pro max variant of iPhone 12",
+        "price": 120000,
+        "isAvailable": true
+    },
+    {
+        "id": "e7f35219-7986-11eb-bd65-98fa9b64e75b",
+        "name": "iPhone 12 Mini",
+        "description": "Mini variant of iPhone 12",
+        "price": 60000,
+        "isAvailable": true
+    },
+    {
+        "id": "e7f35219-8986-11eb-bd65-98fa9b64e75b",
+        "name": "iPhone 12",
+        "description": "Base variant of iPhone 12",
+        "price": 78000,
+        "isAvailable": true
+    }
+]

entity/product.go

@@ -0,0 +1,123 @@
+package entity
+
+import (
+	"encoding/json"
+	"errors"
+	"io/ioutil"
+	"os"
+)
+
+//Product defines a structure for an item in product catalog
+type Product struct {
+	ID          string  `json:"id"`
+	Name        string  `json:"name"`
+	Description string  `json:"description"`
+	Price       float64 `json:"price"`
+	IsAvailable bool    `json:"isAvailable"`
+}
+
+// ErrNoProduct is used if no product found
+var ErrNoProduct = errors.New("no product found")
+
+// GetProducts returns the JSON file content if available else returns an error.
+func GetProducts() ([]byte, error) {
+	// Read JSON file
+	data, err := ioutil.ReadFile("./data/data.json")
+	if err != nil {
+		return nil, err
+	}
+	return data, nil
+}
+
+// GetProduct takes id as input and returns the corresponding product, else it returns ErrNoProduct error.
+func GetProduct(id string) (Product, error) {
+	// Read JSON file
+	data, err := ioutil.ReadFile("./data/data.json")
+	if err != nil {
+		return Product{}, err
+	}
+	// read products
+	var products []Product
+	err = json.Unmarshal(data, &products)
+	if err != nil {
+		return Product{}, err
+	}
+	// iterate through product array
+	for i := 0; i < len(products); i++ {
+		// if we find one product with the given ID
+		if products[i].ID == id {
+			// return product
+			return products[i], nil
+		}
+	}
+	return Product{}, ErrNoProduct
+}
+
+// DeleteProduct takes id as input and deletes the corresponding product, else it returns ErrNoProduct error.
+func DeleteProduct(id string) error {
+	// Read JSON file
+	data, err := ioutil.ReadFile("./data/data.json")
+	if err != nil {
+		return err
+	}
+	// read products
+	var products []Product
+	err = json.Unmarshal(data, &products)
+	if err != nil {
+		return err
+	}
+	// iterate through product array
+	for i := 0; i < len(products); i++ {
+		// if we find one product with the given ID
+		if products[i].ID == id {
+			products = removeElement(products, i)
+			// Write Updated JSON file
+			updatedData, err := json.Marshal(products)
+			if err != nil {
+				return err
+			}
+			err = ioutil.WriteFile("./data/data.json", updatedData, os.ModePerm)
+			if err != nil {
+				return err
+			}
+			return nil
+		}
+	}
+	return ErrNoProduct
+}
+
+// AddProduct adds an input product to the product list in JSON document.
+func AddProduct(product Product) error {
+	// Load existing products and append the data to product list
+	var products []Product
+	data, err := ioutil.ReadFile("./data/data.json")
+	if err != nil {
+		return err
+	}
+	// Load our JSON file to memory using array of products
+	err = json.Unmarshal(data, &products)
+	if err != nil {
+		return err
+	}
+	// Add new Product to our list
+	products = append(products, product)
+
+	// Write Updated JSON file
+	updatedData, err := json.Marshal(products)
+	if err != nil {
+		return err
+	}
+	err = ioutil.WriteFile("./data/data.json", updatedData, os.ModePerm)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// removeElement is used to remove element from product array at given index
+func removeElement(arr []Product, index int) []Product {
+	ret := make([]Product, 0)
+	ret = append(ret, arr[:index]...)
+	return append(ret, arr[index+1:]...)
+}

go.mod

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+module github.com/HelloWorld/goProductAPI
+
+go 1.16
+
+require github.com/gorilla/mux v1.8.0

go.sum

@@ -0,0 +1,2 @@
+github.com/gorilla/mux v1.8.0 h1:i40aqfkR1h2SlN9hojwV5ZA91wcXFOvkdNIeFDP5koI=
+github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=

handlers/handlers.go

@@ -0,0 +1,166 @@
+package handlers
+
+import (
+	"crypto/sha256"
+	"crypto/subtle"
+	"encoding/json"
+	"errors"
+	"io/ioutil"
+	"net/http"
+	"os"
+
+	"github.com/HelloWorld/goProductAPI/entity"
+	"github.com/gorilla/mux"
+)
+
+// GetProductsHandler is used to get data inside the products defined on our product catalog
+func GetProductsHandler() http.HandlerFunc {
+	return func(rw http.ResponseWriter, r *http.Request) {
+		data, err := entity.GetProducts()
+		if err != nil {
+			rw.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+		// Write the body with JSON data
+		rw.Header().Add("content-type", "application/json")
+		rw.WriteHeader(http.StatusFound)
+		rw.Write(data)
+	}
+}
+
+// GetProductHandler is used to get data inside the products defined on our product catalog
+func GetProductHandler() http.HandlerFunc {
+	return func(rw http.ResponseWriter, r *http.Request) {
+		// Read product ID
+		productID := mux.Vars(r)["id"]
+		product, err := entity.GetProduct(productID)
+		if err != nil {
+			rw.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+		responseData, err := json.Marshal(product)
+		if err != nil {
+			// Check if it is No product error or any other error
+			if errors.Is(err, entity.ErrNoProduct) {
+				// Write Header if no related product found.
+				rw.WriteHeader(http.StatusNoContent)
+			} else {
+				rw.WriteHeader(http.StatusInternalServerError)
+			}
+			return
+		}
+		// Write body with found product
+		rw.Header().Add("content-type", "application/json")
+		rw.WriteHeader(http.StatusFound)
+		rw.Write(responseData)
+	}
+}
+
+// CreateProductHandler is used to create a new product and add to our product store.
+func CreateProductHandler() http.HandlerFunc {
+	return func(rw http.ResponseWriter, r *http.Request) {
+		// Read incoming JSON from request body
+		data, err := ioutil.ReadAll(r.Body)
+		// If no body is associated return with StatusBadRequest
+		if err != nil {
+			rw.WriteHeader(http.StatusBadRequest)
+			return
+		}
+		// Check if data is proper JSON (data validation)
+		var product entity.Product
+		err = json.Unmarshal(data, &product)
+		if err != nil {
+			rw.WriteHeader(http.StatusExpectationFailed)
+			rw.Write([]byte("Invalid Data Format"))
+			return
+		}
+		err = entity.AddProduct(product)
+		if err != nil {
+			rw.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+		// return after writing Body
+		rw.WriteHeader(http.StatusCreated)
+		rw.Write([]byte("Added New Product"))
+	}
+}
+
+// DeleteProductHandler deletes the product with given ID.
+func DeleteProductHandler() http.HandlerFunc {
+	return func(rw http.ResponseWriter, r *http.Request) {
+		// Read product ID
+		productID := mux.Vars(r)["id"]
+		err := entity.DeleteProduct(productID)
+		if err != nil {
+			// Check if it is No product error or any other error
+			if errors.Is(err, entity.ErrNoProduct) {
+				// Write Header if no related product found.
+				rw.WriteHeader(http.StatusNoContent)
+			} else {
+				rw.WriteHeader(http.StatusInternalServerError)
+			}
+			return
+		}
+		// Write Header with Accepted Status (done operation)
+		rw.WriteHeader(http.StatusAccepted)
+	}
+}
+
+// UpdateProductHandler updates the product with given ID.
+func UpdateProductHandler() http.HandlerFunc {
+	return func(rw http.ResponseWriter, r *http.Request) {
+		// Read product ID
+		productID := mux.Vars(r)["id"]
+		err := entity.DeleteProduct(productID)
+		if err != nil {
+			if errors.Is(err, entity.ErrNoProduct) {
+				rw.WriteHeader(http.StatusNoContent)
+			} else {
+				rw.WriteHeader(http.StatusInternalServerError)
+			}
+			return
+		}
+		// Read incoming JSON from request body
+		data, err := ioutil.ReadAll(r.Body)
+		// If no body is associated return with StatusBadRequest
+		if err != nil {
+			rw.WriteHeader(http.StatusBadRequest)
+			return
+		}
+		// Check if data is proper JSON (data validation)
+		var product entity.Product
+		err = json.Unmarshal(data, &product)
+		if err != nil {
+			rw.WriteHeader(http.StatusExpectationFailed)
+			rw.Write([]byte("Invalid Data Format"))
+			return
+		}
+		// Addproduct with the requested body
+		err = entity.AddProduct(product)
+		if err != nil {
+			rw.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+		// Write Header if no related product found.
+		rw.WriteHeader(http.StatusAccepted)
+	}
+}
+
+func AuthHandler(h http.Handler) http.HandlerFunc {
+	return func(rw http.ResponseWriter, r *http.Request) {
+		user, pass, ok := r.BasicAuth()
+		if ok {
+			username := sha256.Sum256([]byte(os.Getenv("USER_NAME")))
+			password := sha256.Sum256([]byte(os.Getenv("USER_PASS")))
+			userHash := sha256.Sum256([]byte(user))
+			passHash := sha256.Sum256([]byte(pass))
+			validUser := subtle.ConstantTimeCompare(userHash[:],username[:]) == 1
+			validPass := subtle.ConstantTimeCompare(passHash[:],password[:]) == 1
+			if validPass && validUser{
+			    h.ServeHTTP(rw,r)
+				return
+			}
+		}
+		http.Error(rw, "No/Invalid Credentials", http.StatusUnauthorized)
+	}
+}

main.go

@@ -0,0 +1,32 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/HelloWorld/goProductAPI/handlers"
+	"github.com/gorilla/mux"
+)
+
+func main() {
+	// Create new Router
+	router := mux.NewRouter()
+	// route properly to respective handlers
+	router.Handle("/products", handlers.GetProductsHandler()).Methods("GET")
+	router.Handle("/products", handlers.CreateProductHandler()).Methods("POST")
+	router.Handle("/products/{id}", handlers.GetProductHandler()).Methods("GET")
+	router.Handle("/products/{id}", handlers.DeleteProductHandler()).Methods("DELETE")
+	router.Handle("/products/{id}", handlers.UpdateProductHandler()).Methods("PUT")
+
+	// Create new server and assign the router
+	server := http.Server{
+		Addr:    ":9090",
+		Handler: handlers.AuthHandler(router),
+	}
+	fmt.Println("Staring Product Catalog server on Port 9090")
+	// Start Server on defined port/host.
+	err := server.ListenAndServeTLS("server.crt", "server.key")
+	if err != nil {
+		fmt.Printf("Failed to start HTTPS server: %s", err.Error())
+	}
+}

server.crt

@@ -0,0 +1,22 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----

server.key

@@ -0,0 +1,27 @@
+-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----