feat: add stock ticker app

.dockerignore

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+*
+!*.go
+!go.sum
+!go.mod

.gitignore

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+stock-ticker

Dockerfile

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+FROM golang:1.19.6-alpine AS builder
+
+ENV CGO_ENABLED=0
+ENV GOOS=linux
+ENV GOARCH=amd64
+
+ADD *.go /workspace/
+ADD go.mod /workspace/
+
+WORKDIR /workspace
+
+RUN go build -a -v -ldflags="-s -w" -o /workspace/stock-ticker .
+
+FROM gcr.io/distroless/static-debian11
+
+COPY --from=builder /workspace/stock-ticker /stock-ticker
+
+USER 1000
+
+ENTRYPOINT ["/stock-ticker"]
+
+HEALTHCHECK NONE

README.md

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+# Stock Ticker

go.mod

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+module gitlab.com/dananglin/stock-ticker
+
+go 1.19

handlers.go

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+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"sort"
+	"strings"
+	"net/http"
+)
+
+func healthCheckHandleFunc(w http.ResponseWriter, _ *http.Request) {
+	w.Header().Set("Content-Type", "text/plain")
+	w.WriteHeader(http.StatusOK)
+
+	fmt.Fprintln(w, "I'm all good!")
+}
+
+func stockPriceHandleFunc(apiKey, symbol string, nWeeks int) func(http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			w.Header().Set("Content-Type", "text/plain")
+			w.WriteHeader(http.StatusMethodNotAllowed)
+
+			fmt.Fprintf(w, "ERROR: The method '%s' is not allow at this endpoint.\n", r.Method)
+
+			return
+		}
+
+		resp, err := http.Get(fmt.Sprintf(requestURLFormat, symbol, apiKey))
+		if err != nil {
+			w.Header().Set("Content-Type", "text/plain")
+			w.WriteHeader(http.StatusBadGateway)
+
+			fmt.Fprintf(w, "ERROR: Unable to get a response from Alpha Vantage; %v\n", err)
+
+			return
+		}
+		defer resp.Body.Close()
+
+		decoder := json.NewDecoder(resp.Body)
+
+		var s Stock
+
+		if err := decoder.Decode(&s); err != nil {
+			w.Header().Set("Content-Type", "text/plain")
+			w.WriteHeader(http.StatusBadGateway)
+
+			fmt.Fprintf(w, "ERROR: Unable to decode the response from Alpha Vantage; %v\n", err)
+
+			return
+		}
+
+		if nWeeks > len(s.TimeSeries) {
+			nWeeks = len(s.TimeSeries)
+		}
+
+		var keys []string
+
+		for k := range s.TimeSeries {
+			keys = append(keys, k)
+		}
+
+		sort.Sort(sort.Reverse(sort.StringSlice(keys)))
+
+		var b strings.Builder
+
+		b.WriteString(fmt.Sprintf(tableFormat, s.MetaData.Symbol))
+
+		for i := 0; i < nWeeks; i++ {
+			b.WriteString(fmt.Sprintf("%s |   %s\n", keys[i], s.TimeSeries[keys[i]].Close))
+		}
+
+		w.Header().Set("Content-Type", "text/plain")
+		w.WriteHeader(http.StatusOK)
+
+		fmt.Fprintln(w, b.String())
+	}
+}

kubernetes/manifest.yaml

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+---
+# Namespace
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: stock-ticker
+  labels:
+    app: stock-ticker
+---
+# ServiceAccount
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: stock-ticker
+  namespace: stock-ticker
+  labels:
+    app: stock-ticker
+---
+# Ingress
+apiVersion: networking.k8s.io
+kind: Ingress
+metadata:
+  name: stock-ticker
+  namespace: stock-ticker
+  labels:
+    app: stock-ticker
+spec:
+  rules:
+  - http:
+    paths:
+    - path: "/"
+      pathType: Prefix
+      backend:
+        service:
+          name: stock-ticker
+          port:
+            number: 80
+---
+# Service
+apiVersion: v1
+kind: Service
+metadata:
+  name: stock-ticker
+  namespace: stock-ticker
+  labels:
+    app: stock-ticker
+spec:
+  selector:
+    app: stock-ticker
+  port:
+  - protocol: TCP
+    port: 80
+    targetPort: web
+---
+# ConfigMap
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: stock-ticker
+  namespace: stock-ticker
+  labels:
+    app: stock-ticker
+data:
+  SYMBOL: "MSFT"
+  NWEEKS: "7"
+---
+# Secret
+apiVersion: v1
+kind: Secret
+metadata:
+  name: stock-ticker-api-key
+  namespace: stock-ticker
+  labels:
+    app: stock-ticker
+type: Opaque
+data:
+  APIKEY: QzIyN1dEOVczTFVWS1ZWOQ==
+---
+# PDB
+apiVersion: policy/v1
+kind: PodDisruptionBudget
+metadata:
+  name: stock-ticker-api-key
+  namespace: stock-ticker
+  labels:
+    app: stock-ticker
+spec:
+  minAvailable: 1
+  selector:
+    matchLabels:
+      app: stock-ticker
+---
+# Deployment
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: stock-ticker
+  namespace: stock-ticker
+  labels:
+    app: stock-ticker
+spec:
+  replicas: 3
+  revisionHistoryLimit: 3
+  selector:
+    matchLabels:
+      app: stock-ticker
+  template:
+    metadata:
+      labels:
+        app: stock-ticker
+    spec:
+      serviceAccountName: stock-ticker
+      securityContext:
+        runAsUser: 1000
+        runAsNonRoot: true
+        runAsGroup: 1000
+      containers:
+      - name: stock-ticker
+        args:
+        - "--address=$(WEBSERVER_HOST):$(WEBSERVER_PORT)"
+        env:
+        - name: SYMBOL
+          valueFrom:
+            configMapKeyRef:
+              name: stock-ticker
+              key: SYMBOL
+        - name: APIKEY
+          valueFrom:
+            secretKeyRef:
+              name: stock-ticker-api-key
+              key: APIKEY
+        - name: NWEEKS
+          valueFrom:
+            configMapKeyRef:
+              name: stock-ticker
+              key: NWEEKS
+        - name: WEBSERVER_HOST
+          valueFrom:
+            fieldRef:
+              fieldPath: status.podIP
+        - name: WEBSERVER_PORT
+          value: "8080"
+        image: ""
+        imagePullPolicy: Always
+        livenessProbe:
+          httpGet:
+            port: 8080
+            path: /healthcheck
+          initialDelaySeconds: 10
+          periodSeconds: 10
+          timeoutSeconds: 3
+        readinessProbe:
+          httpGet:
+            port: 8080
+            path: /healthcheck
+          initialDelaySeconds: 10
+          periodSeconds: 10
+          timeoutSeconds: 3
+        ports:
+        - containerPort: 8080
+          name: web
+          protocol: TCP
+        resources:
+          limits:
+            cpu: 50m
+            memory: 75Mi
+          requests:
+            cpu: 25m
+            memory: 50Mi

main.go

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+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"strconv"
+)
+
+const (
+	requestURLFormat string = "https://www.alphavantage.co/query?function=TIME_SERIES_WEEKLY&symbol=%s&apikey=%s"
+)
+
+var tableFormat = `
+Symbol: %s
+
+Week       | Closing Price
+==========================
+`
+
+func main() {
+	var address string
+
+	flag.StringVar(&address, "address", "0.0.0.0:8080", "the web server's listening address")
+	flag.Parse()
+
+	symbol, err := getEnvironment("SYMBOL")
+	if err != nil {
+		log.Fatalf("ERROR: %v.\n", err)
+	}
+
+	apiKey, err := getEnvironment("APIKEY")
+	if err != nil {
+		log.Fatalf("ERROR: %v.\n", err)
+	}
+
+	nWeeksString, err := getEnvironment("NWEEKS")
+	if err != nil {
+		log.Fatalf("ERROR: %v.\n", err)
+	}
+
+	nWeeks, err := strconv.Atoi(nWeeksString)
+	if err != nil {
+		log.Fatalf("ERROR: Unable to parse the number of days from %s, %v\n", nWeeksString, err)
+	}
+
+	http.HandleFunc("/healthcheck", healthCheckHandleFunc)
+	http.HandleFunc("/stockprice", stockPriceHandleFunc(apiKey, symbol, nWeeks))
+
+	log.Printf("The web server is listening on %s.\n", address)
+
+	log.Fatal(http.ListenAndServe(address, nil))
+}
+
+
+func getEnvironment(key string) (string, error) {
+	value := os.Getenv(key)
+	if value == "" {
+		return "", fmt.Errorf("the environment variable %s is not set", key)
+	}
+
+	return value, nil
+}

types.go

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+package main
+
+type Stock struct {
+	MetaData   MetaData             `json:"Meta Data"`
+	TimeSeries map[string]StockInfo `json:"Weekly Time Series"`
+}
+
+type MetaData struct {
+	Symbol string `json:"2. Symbol"`
+}
+
+type StockInfo struct {
+	Close string `json:"4. close"`
+}