Add shipping service.

src/shippingservice/Dockerfile

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+FROM golang:1.10.3-alpine3.7 as deps
+
+RUN apk add --no-cache \
+  ca-certificates \
+  curl \
+  git \
+  gcc \
+  libffi-dev \
+  make \
+  musl-dev \
+  protobuf \
+  tar
+
+ENV PATH=$PATH:$GOPATH/bin
+RUN go get -u google.golang.org/grpc && \
+  go get github.com/golang/protobuf/protoc-gen-go
+
+FROM deps as builder
+WORKDIR $GOPATH/src/microservices-demo/shipping
+COPY src/shippingservice $GOPATH/src/microservices-demo/shipping
+COPY pb/demo.proto $GOPATH/src/microservices-demo/pb/demo.proto
+
+RUN protoc -I ../pb/ ../pb/demo.proto --go_out=plugins=grpc:../pb
+RUN go build -o /shipping/shipit
+
+FROM golang:1.10.3-alpine3.7 as release
+COPY --from=builder /shipping/shipit /shipit
+ENV APP_PORT=50051
+
+# @TODO add light init system.
+ENTRYPOINT /shipit

src/shippingservice/README.md

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+# Shipping Service
+
+The Shipping service provides price quote, tracking IDs, and the impression of order fulfillment & shipping processes.
+
+## Build
+
+From repository root, run:
+
+```
+docker build --file src/shippingservice/Dockerfile .
+```
+
+## Test
+
+```
+go test .
+```

src/shippingservice/main.go

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+package main
+
+import (
+	"fmt"
+	"log"
+	"net"
+	"os"
+
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/reflection"
+
+	pb "microservices-demo/pb"
+)
+
+
+const (
+	default_port = "50051"
+)
+
+// server controls RPC service responses.
+type server struct{}
+
+// GetQuote produces a shipping quote (cost) in USD.
+func (s *server) GetQuote(ctx context.Context, in *pb.GetQuoteRequest) (*pb.GetQuoteResponse, error) {
+
+	// 1. Our quote system requires the total number of items to be shipped.
+	count := 0
+	for _, item := range in.Items {
+		count += int(item.Quantity)
+	}
+
+	// 2. Generate a quote based on the total number of items to be shipped.
+	quote := CreateQuoteFromCount(count)
+
+	// 3. Generate a response.
+	return &pb.GetQuoteResponse{
+		CostUsd: &pb.MoneyAmount{
+			Decimal: quote.Dollars,
+			Fractional: quote.Cents,
+		},
+	}, nil
+
+}
+
+// ShipOrder mocks that the requested items will be shipped.
+// It supplies a tracking ID for notional lookup of shipment delivery status.
+func (s *server) ShipOrder(ctx context.Context, in *pb.ShipOrderRequest) (*pb.ShipOrderResponse, error) {
+	// 1. Create a Tracking ID
+	baseAddress := fmt.Sprintf("%s, %s, %s", in.Address.StreetAddress_1, in.Address.StreetAddress_2, in.Address.City)
+	id := CreateTrackingId(baseAddress)
+
+	// 2. Generate a response.
+	return &pb.ShipOrderResponse{
+		TrackingId: id,
+	}, nil
+}
+
+func main() {
+	port := default_port
+	if value, ok := os.LookupEnv("APP_PORT"); ok {
+		port = value
+	}
+	port = fmt.Sprintf(":%s", port)
+
+	lis, err := net.Listen("tcp", port)
+	if err != nil {
+		log.Fatalf("failed to listen: %v", err)
+	}
+	s := grpc.NewServer()
+	pb.RegisterShippingServiceServer(s, &server{})
+	log.Printf("Shipping Service listening on port %s", port)
+
+	// Register reflection service on gRPC server.
+	reflection.Register(s)
+	if err := s.Serve(lis); err != nil {
+		log.Fatalf("failed to serve: %v", err)
+	}
+}

src/shippingservice/quote.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"fmt"
+	"math"
+)
+
+// Quote represents a currency value.
+type Quote struct {
+	Dollars uint32
+	Cents   uint32
+}
+
+// String representation of the Quote.
+func (q Quote) String() string {
+	return fmt.Sprintf("$%d.%d", q.Dollars, q.Cents)
+}
+
+// CreateQuoteFromCount takes a number of items and returns a Price struct.
+func CreateQuoteFromCount(count int) Quote {
+	return CreateQuoteFromFloat(quoteByCountFloat(count))
+}
+
+// CreateQuoteFromFloat takes a price represented as a float and creates a Price struct.
+func CreateQuoteFromFloat(value float64) Quote {
+	units, fraction := math.Modf(value)
+	return Quote{
+		uint32(units),
+		uint32(math.Trunc(fraction * 100)),
+	}
+}
+
+// quoteByCountFloat takes a number of items and generates a price quote represented as a float.
+func quoteByCountFloat(count int) float64 {
+	if count == 0 {
+		return 0
+	}
+	count64 := float64(count)
+	var p float64 = 1 + (count64 * 0.2)
+	return count64 + math.Pow(3, p)
+}

src/shippingservice/shippingservice_test.go

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+package main
+
+import(
+	"testing"
+	"golang.org/x/net/context"
+
+	pb "microservices-demo/pb"
+)
+
+// TestGetQuote is a basic check on the GetQuote RPC service.
+func TestGetQuote(t *testing.T) {
+	s := server{}
+
+	// A basic test case to test logic and protobuf interactions.
+	req := &pb.GetQuoteRequest{
+		Address: &pb.Address{
+			StreetAddress_1: "Muffin Man",
+			StreetAddress_2: "Drury Lane",
+			City: "London",
+			Country: "England",
+		},
+		Items: []*pb.CartItem{
+			{
+				ProductId: "23",
+				Quantity: 1,
+			},
+			{
+				ProductId: "46",
+				Quantity: 3,
+			},
+		},
+	}
+
+	res, err := s.GetQuote(context.Background(), req)
+	if err != nil {
+		t.Errorf("TestGetQuote (%v) failed", err)
+	}
+	if res.CostUsd.Decimal != 11 || res.CostUsd.Fractional != 22 {
+		t.Errorf("TestGetQuote: Quote value '%d.%d' does not match expected '%s'", res.CostUsd.Decimal, res.CostUsd.Fractional, "11.22")
+	}
+}
+
+// TestShipOrder is a basic check on the ShipOrder RPC service.
+func TestShipOrder(t *testing.T) {
+	s := server{}
+
+	// A basic test case to test logic and protobuf interactions.
+	req := &pb.ShipOrderRequest{
+		Address: &pb.Address{
+			StreetAddress_1: "Muffin Man",
+			StreetAddress_2: "Drury Lane",
+			City: "London",
+			Country: "England",
+		},
+		Items: []*pb.CartItem{
+			{
+				ProductId: "23",
+				Quantity: 1,
+			},
+			{
+				ProductId: "46",
+				Quantity: 3,
+			},
+		},
+	}
+
+	res, err := s.ShipOrder(context.Background(), req)
+	if err != nil {
+		t.Errorf("TestShipOrder (%v) failed", err)
+	}
+	// @todo improve quality of this test to check for a pattern such as '[A-Z]{2}-\d+-\d+'.
+	if len(res.TrackingId) != 18 {
+		t.Errorf("TestShipOrder: Tracking ID is malformed - has %d characters, %d expected", len(res.TrackingId), 18)
+	}
+}

src/shippingservice/tracker.go

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+package main
+
+import (
+	"fmt"
+	"math/rand"
+	"time"
+)
+
+// seeded determines if the random number generator is ready.
+var seeded bool = false
+
+// CreateTrackingId generates a tracking ID.
+func CreateTrackingId(salt string) string {
+	if !seeded {
+		rand.Seed(time.Now().UnixNano())
+		seeded = true
+	}
+
+	return fmt.Sprintf("%c%c-%d%s-%d%s",
+		getRandomLetterCode(),
+		getRandomLetterCode(),
+		len(salt),
+		getRandomNumber(3),
+		len(salt)/2,
+		getRandomNumber(7),
+	)
+}
+
+// getRandomLetterCode generates a code point value for a capital letter.
+func getRandomLetterCode() uint32 {
+	return 65 + uint32(rand.Intn(27))
+}
+
+// getRandomNumber generates a string representation of a number with the requested number of digits.
+func getRandomNumber(digits int) string {
+	str := ""
+	for i := 0; i < digits; i++ {
+		str = fmt.Sprintf("%s%d", str, rand.Intn(10))
+	}
+
+	return str
+}