update golang example

Signed-off-by: Sarthak Sharma <sartsharma@microsoft.com>

README.md

@@ -17,8 +17,7 @@ Pick a building block API (for example, pub-sub, state management) and rapidly t
 | [Bindings](./bindings/) | Work with external systems using input bindings to respond to events and output bindings to call operations|
 | [Secrets Management](./secrets_management/) | Securely fetch secrets |
 | Actors | Coming soon... |
-| Observability | Coming soon... |
-| [Configuration](./configuration) | Consume configuration items as key/value pairs and subscribe to changes whenever a configuration item changes |
+| [Configuration](./configuration) | Get configuration items as key/value pairs or subscribe to changes whenever a configuration item changes |
 
 ### Tutorials
 Go deeper into a topic or scenario, oftentimes using building block APIs together to solve problems (for example, build a distributed calculator, build and deploy an app to Kubernetes).

configuration/go/http/order-processor/app.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
@@ -8,6 +9,7 @@ import (
 	"net/http"
 	"os"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/gorilla/mux"
@@ -41,15 +43,24 @@ func main() {
 		fmt.Println("Configuration for "+item+":", string(result))
 	}
 
-	// Create POST endpoint to receive config updates
-	go startServerToListen()
+	var subscriptionId string
+
+	wg := new(sync.WaitGroup)
+	wg.Add(2)
+	// Start HTTP Server to receive config updates for 20 seconds and then shutdown and unsubscribe from config updates
+	go func() {
+		startServerToListen(&subscriptionId)
+		wg.Done()
+	}()
 	// Subscribe for config updates
-	go subscribeToConfigUpdates()
-	// Block main goroutine for 15 seconds and then stop the app
-	time.Sleep(15 * time.Second)
+	go func() {
+		subscribeToConfigUpdates(&subscriptionId)
+		wg.Done()
+	}()
+	wg.Wait()
 }
 
-func subscribeToConfigUpdates() {
+func subscribeToConfigUpdates(subscriptionId *string) {
 	// Add delay to allow app channel to be ready
 	time.Sleep(3 * time.Second)
 
@@ -67,18 +78,55 @@ func subscribeToConfigUpdates() {
 		var subid map[string]interface{}
 		json.Unmarshal(sub, &subid)
 		fmt.Println("App subscribed to config changes with subscription id:", subid["id"])
-		return
+		*subscriptionId = subid["id"].(string)
 	} else {
 		fmt.Println("Error subscribing to config updates: ", string(sub))
 		os.Exit(1)
 	}
 }
 
-func startServerToListen() {
+func startServerToListen(subscriptionId *string) {
 	r := mux.NewRouter()
+	httpServer := http.Server{
+		Addr:    ":" + appPort,
+		Handler: r,
+	}
 	r.HandleFunc("/configuration/configstore/{configItem}", configUpdateHandler).Methods("POST")
-	if err := http.ListenAndServe(":"+appPort, r); err != nil {
-		log.Panic(err)
+
+	// Shutdown Server after 20 seconds
+	time.AfterFunc(20*time.Second, func() {
+		err := httpServer.Shutdown(context.Background())
+		if err != nil {
+			fmt.Println("Error shutting down HTTP server, err:" + err.Error())
+		}
+	})
+
+	// Register shutdown function
+	httpServer.RegisterOnShutdown(func() {
+		fmt.Println("Shutting down HTTP server")
+		unsubscribeFromConfigUpdates(*subscriptionId)
+	})
+
+	// Start HTTP server
+	if err := httpServer.ListenAndServe(); err != nil {
+		log.Println("HTTP server error:", err)
+	}
+}
+
+func unsubscribeFromConfigUpdates(subscriptionId string) {
+	unsubscribe, err := http.Get(DAPR_HOST + ":" + DAPR_HTTP_PORT + "/v1.0-alpha1/configuration/" + DAPR_CONFIGURATION_STORE + "/" + subscriptionId + "/unsubscribe")
+	if err != nil {
+		fmt.Println("Error unsubscribing from config updates, err:" + err.Error())
+	}
+	unsub, err := ioutil.ReadAll(unsubscribe.Body)
+	if err != nil {
+		fmt.Print("Unable to read unsubscribe response, err: " + err.Error())
+	}
+	if strings.Contains(string(unsub), "true") {
+		fmt.Println("App unsubscribed from config changes")
+		return
+	} else {
+		fmt.Println("Error unsubscribing from config updates: ", string(unsub))
 	}
 }
 

configuration/go/sdk/order-processor/app.go

@@ -19,7 +19,7 @@ func main() {
 	if err != nil {
 		log.Panic(err)
 	}
-	ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
+	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
 	defer cancel()
 
 	// Get config items from config store
@@ -49,7 +49,7 @@ func main() {
 		os.Exit(1)
 	}
 
-	// Exit app after 15 seconds
+	// Exit app after 20 seconds
 	select {
 	case <-ctx.Done():
 		os.Exit(0)