Rewrite zone-printer app

- This simplifies the sample app a great deal
  since it no longer uses nginx (confuses users),
  it has simpler deployment manifest
- This new sampel app is a web server directly,
  written in Go, it renders the flag of the gce
  region in the response.
- It is clean and understandable code as opposed
  to ConfigMap/nginx.conf hack we used to have.

This will likely require a lot of README.md changes,
so please hold off until the other PRs regarding tutorial
updates are merged.

Signed-off-by: Ahmet Alp Balkan <[email protected]>

examples/zone-printer/ingress/https-ingress.yaml → examples/zone-printer/ingress/ingress-https.yaml

@@ -1,14 +1,14 @@
 apiVersion: extensions/v1beta1
 kind: Ingress
 metadata:
-  name: nginx
+  name: zoneprinter
   annotations:
-    kubernetes.io/ingress.global-static-ip-name: $ZP_KUBEMCI_IP
     kubernetes.io/ingress.class: gce-multi-cluster
+    kubernetes.io/ingress.global-static-ip-name: $ZP_KUBEMCI_IP
 spec:
   tls:
   # This assumes tls-secret exists.
   - secretName: tls-secret
   backend:
-    serviceName: nginx
+    serviceName: zoneprinter
     servicePort: 80

examples/zone-printer/ingress/nginx.yaml → examples/zone-printer/ingress/ingress.yaml

@@ -1,11 +1,11 @@
 apiVersion: extensions/v1beta1
 kind: Ingress
 metadata:
-  name: nginx
+  name: zoneprinter
   annotations:
-    kubernetes.io/ingress.global-static-ip-name: $ZP_KUBEMCI_IP
     kubernetes.io/ingress.class: gce-multi-cluster
+    kubernetes.io/ingress.global-static-ip-name: $ZP_KUBEMCI_IP
 spec:
   backend:
-    serviceName: nginx
+    serviceName: zoneprinter
     servicePort: 80

examples/zone-printer/manifests/deployment.yaml

@@ -0,0 +1,20 @@
+apiVersion: apps/v1beta1
+kind: Deployment
+metadata:
+  name: zoneprinter
+  labels:
+    app: zoneprinter
+spec:
+  selector:
+    matchLabels:
+      app: zoneprinter
+  template:
+    metadata:
+      labels:
+        app: zoneprinter
+    spec:
+      containers:
+      - name: frontend
+        image: zoneprinter:latest
+        ports:
+          - containerPort: 80

examples/zone-printer/app/nginx-svc.yaml → examples/zone-printer/manifests/service.yaml

@@ -1,16 +1,14 @@
 apiVersion: v1
 kind: Service
 metadata:
+  name: zoneprinter
   labels:
-    app: nginx
-  name: nginx
+    app: zoneprinter
 spec:
+  type: NodePort
+  selector:
+    app: zoneprinter
   ports:
-  - port: 80
-    protocol: TCP
-    targetPort: 80
-    name: http
+  - name: http
+    port: 80
     nodePort: 30061
-  selector:
-    app: nginx
-  type: NodePort

examples/zone-printer/src/Dockerfile

@@ -0,0 +1,12 @@
+FROM golang:1.10-alpine as compiler
+RUN apk add --no-cache git
+RUN go get cloud.google.com/go/compute/metadata
+WORKDIR /go/src/zoneprinter
+COPY . .
+RUN go install
+
+FROM alpine
+COPY --from=compiler /go/bin/zoneprinter ./zoneprinter
+ENTRYPOINT ./zoneprinter
+EXPOSE 80
+

examples/zone-printer/src/main.go

@@ -0,0 +1,145 @@
+// Copyright 2018 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+	"strings"
+
+	"cloud.google.com/go/compute/metadata"
+)
+
+var (
+	computeZone string
+)
+
+func main() {
+	if !metadata.OnGCE() {
+		log.Println("warn: not running on gce")
+	} else {
+		zone, err := metadata.Zone()
+		if err != nil {
+			log.Fatalf("failed to get compute zone: %+v", err)
+		}
+		computeZone = zone
+		log.Printf("info: determined zone: %q", zone)
+	}
+
+	log.Println("starting to listen on port 80")
+	http.HandleFunc("/", handle)
+	err := http.ListenAndServe(":80", nil)
+	log.Fatal(err)
+}
+
+func handle(w http.ResponseWriter, r *http.Request) {
+	var srcIP string
+	if ipHeader := r.Header.Get("X-Forwarded-For"); ipHeader != "" {
+		srcIP = ipHeader
+	} else {
+		srcIP = r.RemoteAddr
+	}
+	log.Printf("received request method=%s path=%q src=%q", r.Method, r.URL.Path, srcIP)
+
+	if computeZone == "" {
+		fmt.Fprintf(w, `<!DOCTYPE html>
+				<h1>Cannot determine the compute zone :(</h1>
+				<p>Is it running on a Google Compute Engine instance?</p>`)
+		return
+	}
+
+	region := computeZone[:strings.LastIndex(computeZone, "-")]
+	dc, ok := datacenters[region]
+	if !ok {
+		fmt.Fprintf(w, `<!DOCTYPE html>
+		<h4>Welcome from Google Cloud datacenters at:<h4>
+		<h1>%s!</h1>`, computeZone)
+		return
+	}
+	fmt.Fprintf(w, `<!DOCTYPE html>
+		<h4>Welcome from Google Cloud datacenters at:</h4>
+		<h1>%s</h1>
+		<h3>You are now connected to &quot;%s&quot;</h3>
+		<img src="%s" style="width: 640px; height: auto; border: 1px solid black"/>`, dc.location, computeZone, dc.flagURL)
+}
+
+var (
+	// datacenters adopted from https://cloud.google.com/compute/docs/regions-zones/
+	datacenters = map[string]struct {
+		location string
+		flagURL  string // flag images must be public domain
+	}{
+		"northamerica-northeast1": {
+			location: "Montréal, Canada",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/commons/d/d9/Flag_of_Canada_%28Pantone%29.svg",
+		},
+		"us-central1": {
+			location: "Council Bluffs, Iowa, USA",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/en/a/a4/Flag_of_the_United_States.svg",
+		},
+		"us-west1": {
+			location: "The Dalles, Oregon, USA",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/en/a/a4/Flag_of_the_United_States.svg",
+		},
+		"us-east4": {
+			location: "Ashburn, Virginia, USA",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/en/a/a4/Flag_of_the_United_States.svg",
+		},
+		"us-east1": {
+			location: "Moncks Corner, South Carolina, USA",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/en/a/a4/Flag_of_the_United_States.svg",
+		},
+		"southamerica-east1": {
+			location: "São Paulo, Brazil",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/en/0/05/Flag_of_Brazil.svg",
+		},
+		"europe-west1": {
+			location: "St. Ghislain, Belgium",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/commons/6/65/Flag_of_Belgium.svg",
+		},
+		"europe-west2": {
+			location: "London, U.K.",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/en/a/ae/Flag_of_the_United_Kingdom.svg",
+		},
+		"europe-west3": {
+			location: "Frankfurt, Germany",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/en/b/ba/Flag_of_Germany.svg",
+		},
+		"europe-west4": {
+			location: "Eemshaven, Netherlands",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/commons/2/20/Flag_of_the_Netherlands.svg",
+		},
+		"asia-south1": {
+			location: "Mumbai, India",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/en/4/41/Flag_of_India.svg",
+		},
+		"asia-southeast1": {
+			location: "Jurong West, Singapore",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/commons/4/48/Flag_of_Singapore.svg",
+		},
+		"asia-east1": {
+			location: "Changhua County, Taiwan",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/commons/7/72/Flag_of_the_Republic_of_China.svg",
+		},
+		"asia-northeast1": {
+			location: "Tokyo, Japan",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/en/9/9e/Flag_of_Japan.svg",
+		},
+		"australia-southeast1": {
+			location: "Sydney, Australia",
+			flagURL:  "https://upload.wikimedia.org/wikipedia/en/b/b9/Flag_of_Australia.svg",
+		},
+	}
+)