Add service image build example

Signed-off-by: Christopher Crone <christopher.crone@docker.com>

examples/service-build/back/back.Dockerfile

@@ -0,0 +1,9 @@
+FROM golang:alpine AS build
+ARG MESSAGE
+WORKDIR /go/src
+COPY main.go .
+RUN CGO_ENABLED=0 go build -o /server -ldflags="-X main.Message=${MESSAGE} -s -w" main.go
+
+FROM scratch AS run
+ENTRYPOINT ["/server"]
+COPY --from=build /server /server

examples/service-build/back/main.go

@@ -0,0 +1,23 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+)
+
+var (
+	// Message is the text to serve
+	Message string
+)
+
+func main() {
+	if Message == "" {
+		Message = "<h1>Hello from Docker App build demo!</h1>"
+	}
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		fmt.Printf("Serve request from: %s\n", r.RemoteAddr)
+		fmt.Fprintf(w, Message)
+	})
+	log.Fatal(http.ListenAndServe(":5000", nil))
+}

examples/service-build/build-demo.dockerapp/docker-compose.yml

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+version: "3.7"
+
+services:
+  front:
+    image: front
+    build:
+      context: front/
+      dockerfile: front.Dockerfile
+    ports:
+      - "${front.port}:80"
+
+  back:
+    image: back
+    build:
+      context: back/
+      dockerfile: back.Dockerfile
+      args:
+        - MESSAGE

examples/service-build/build-demo.dockerapp/metadata.yml

@@ -0,0 +1,10 @@
+# Version of the application
+version: 0.1.0
+# Name of the application
+name: build-demo
+# A short description of the application
+description: 
+# List of application maintainers with name and email for each
+maintainers:
+  - name: chris
+    email: 

examples/service-build/build-demo.dockerapp/parameters.yml

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+front:
+  port: 8080

examples/service-build/front/front.Dockerfile

@@ -0,0 +1,2 @@
+FROM nginx:alpine
+COPY nginx-conf /etc/nginx/conf.d/default.conf

examples/service-build/front/nginx-conf

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+server {
+    listen 80;
+    server_name localhost;
+
+    location / {
+        proxy_pass http://back:5000/;
+        proxy_set_header Host "localhost";
+    }
+}