Implement graceful shutdown

- Shutdown the HTTP server before exiting
- Persist data to store before exiting, if applicable

controller/controller.go

@@ -3,6 +3,7 @@ package controller
 import (
 	"bytes"
 	"compress/gzip"
+	"context"
 	"encoding/json"
 	"fmt"
 	"log"
@@ -59,7 +60,15 @@ func Handle() {
 	if os.Getenv("ROUTER_TEST") == "true" {
 		return
 	}
-	log.Fatal(server.ListenAndServe())
+	log.Println("[controller][Handle]", server.ListenAndServe())
+}
+
+// Shutdown stops the server
+func Shutdown() {
+	if server != nil {
+		_ = server.Shutdown(context.TODO())
+		server = nil
+	}
 }
 
 // CreateRouter creates the router for the http server

controller/controller_test.go

@@ -156,6 +156,7 @@ func TestHandle(t *testing.T) {
 	config.Set(cfg)
 	_ = os.Setenv("ROUTER_TEST", "true")
 	_ = os.Setenv("ENVIRONMENT", "dev")
+	defer os.Clearenv()
 	Handle()
 	request, _ := http.NewRequest("GET", "/health", nil)
 	responseRecorder := httptest.NewRecorder()
@@ -167,3 +168,12 @@ func TestHandle(t *testing.T) {
 		t.Fatal("server should've been set (but because we set ROUTER_TEST, it shouldn't have been started)")
 	}
 }
+
+func TestShutdown(t *testing.T) {
+	// Pretend that we called controller.Handle(), which initializes the server variable
+	server = &http.Server{}
+	Shutdown()
+	if server != nil {
+		t.Error("server should've been shut down")
+	}
+}