feat: Bundle assets in binary using go:embed

Dockerfile

@@ -13,7 +13,6 @@ RUN CGO_ENABLED=0 GOOS=linux go build -mod vendor -a -installsuffix cgo -o gatus
 FROM scratch
 COPY --from=builder /app/gatus .
 COPY --from=builder /app/config.yaml ./config/config.yaml
-COPY --from=builder /app/web/static ./web/static
 COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
 ENV PORT=8080
 EXPOSE ${PORT}

config/config_test.go

@@ -17,7 +17,6 @@ import (
 	"github.com/TwiN/gatus/v4/alerting/provider/telegram"
 	"github.com/TwiN/gatus/v4/alerting/provider/twilio"
 	"github.com/TwiN/gatus/v4/client"
-	"github.com/TwiN/gatus/v4/config/ui"
 	"github.com/TwiN/gatus/v4/config/web"
 	"github.com/TwiN/gatus/v4/core"
 	"github.com/TwiN/gatus/v4/storage"
@@ -39,10 +38,6 @@ func TestLoadDefaultConfigurationFile(t *testing.T) {
 
 func TestParseAndValidateConfigBytes(t *testing.T) {
 	file := t.TempDir() + "/test.db"
-	ui.StaticFolder = "../web/static"
-	defer func() {
-		ui.StaticFolder = "./web/static"
-	}()
 	config, err := parseAndValidateConfigBytes([]byte(fmt.Sprintf(`
 storage:
   type: sqlite

config/ui/ui.go

@@ -4,6 +4,8 @@ import (
 	"bytes"
 	"errors"
 	"html/template"
+
+	"github.com/TwiN/gatus/v4/web"
 )
 
 const (
@@ -14,10 +16,6 @@ const (
 )
 
 var (
-	// StaticFolder is the path to the location of the static folder from the root path of the project
-	// The only reason this is exposed is to allow running tests from a different path than the root path of the project
-	StaticFolder = "./web/static"
-
 	ErrButtonValidationFailed = errors.New("invalid button configuration: missing required name or link")
 )
 
@@ -71,7 +69,7 @@ func (cfg *Config) ValidateAndSetDefaults() error {
 		}
 	}
 	// Validate that the template works
-	t, err := template.ParseFiles(StaticFolder + "/index.html")
+	t, err := template.ParseFS(static.FileSystem, static.IndexPath)
 	if err != nil {
 		return err
 	}

config/ui/ui_test.go

@@ -6,10 +6,6 @@ import (
 )
 
 func TestConfig_ValidateAndSetDefaults(t *testing.T) {
-	StaticFolder = "../../web/static"
-	defer func() {
-		StaticFolder = "./web/static"
-	}()
 	cfg := &Config{
 		Title:  "",
 		Header: "",

controller/controller.go

@@ -9,7 +9,6 @@ import (
 	"time"
 
 	"github.com/TwiN/gatus/v4/config"
-	"github.com/TwiN/gatus/v4/config/ui"
 	"github.com/TwiN/gatus/v4/controller/handler"
 )
 
@@ -21,7 +20,7 @@ var (
 
 // Handle creates the router and starts the server
 func Handle(cfg *config.Config) {
-	var router http.Handler = handler.CreateRouter(ui.StaticFolder, cfg)
+	var router http.Handler = handler.CreateRouter(cfg)
 	if os.Getenv("ENVIRONMENT") == "dev" {
 		router = handler.DevelopmentCORS(router)
 	}

controller/handler/badge_test.go

@@ -62,7 +62,7 @@ func TestBadge(t *testing.T) {
 
 	watchdog.UpdateEndpointStatuses(cfg.Endpoints[0], &core.Result{Success: true, Connected: true, Duration: time.Millisecond, Timestamp: time.Now()})
 	watchdog.UpdateEndpointStatuses(cfg.Endpoints[1], &core.Result{Success: false, Connected: false, Duration: time.Second, Timestamp: time.Now()})
-	router := CreateRouter("../../web/static", cfg)
+	router := CreateRouter(cfg)
 	type Scenario struct {
 		Name         string
 		Path         string

controller/handler/chart_test.go

@@ -30,7 +30,7 @@ func TestResponseTimeChart(t *testing.T) {
 	}
 	watchdog.UpdateEndpointStatuses(cfg.Endpoints[0], &core.Result{Success: true, Duration: time.Millisecond, Timestamp: time.Now()})
 	watchdog.UpdateEndpointStatuses(cfg.Endpoints[1], &core.Result{Success: false, Duration: time.Second, Timestamp: time.Now()})
-	router := CreateRouter("../../web/static", cfg)
+	router := CreateRouter(cfg)
 	type Scenario struct {
 		Name         string
 		Path         string

controller/handler/endpoint_status_test.go

@@ -97,7 +97,7 @@ func TestEndpointStatus(t *testing.T) {
 	}
 	watchdog.UpdateEndpointStatuses(cfg.Endpoints[0], &core.Result{Success: true, Duration: time.Millisecond, Timestamp: time.Now()})
 	watchdog.UpdateEndpointStatuses(cfg.Endpoints[1], &core.Result{Success: false, Duration: time.Second, Timestamp: time.Now()})
-	router := CreateRouter("../../web/static", cfg)
+	router := CreateRouter(cfg)
 
 	type Scenario struct {
 		Name         string
@@ -153,7 +153,7 @@ func TestEndpointStatuses(t *testing.T) {
 	// Can't be bothered dealing with timezone issues on the worker that runs the automated tests
 	firstResult.Timestamp = time.Time{}
 	secondResult.Timestamp = time.Time{}
-	router := CreateRouter("../../web/static", &config.Config{Metrics: true})
+	router := CreateRouter(&config.Config{Metrics: true})
 
 	type Scenario struct {
 		Name         string

controller/handler/handler.go

@@ -1,15 +1,17 @@
 package handler
 
 import (
+	"io/fs"
 	"net/http"
 
 	"github.com/TwiN/gatus/v4/config"
+	"github.com/TwiN/gatus/v4/web"
 	"github.com/TwiN/health"
 	"github.com/gorilla/mux"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
-func CreateRouter(staticFolder string, cfg *config.Config) *mux.Router {
+func CreateRouter(cfg *config.Config) *mux.Router {
 	router := mux.NewRouter()
 	if cfg.Metrics {
 		router.Handle("/metrics", promhttp.Handler()).Methods("GET")
@@ -35,11 +37,14 @@ func CreateRouter(staticFolder string, cfg *config.Config) *mux.Router {
 	unprotected.HandleFunc("/v1/endpoints/{key}/response-times/{duration}/chart.svg", ResponseTimeChart).Methods("GET")
 	// Misc
 	router.Handle("/health", health.Handler().WithJSON(true)).Methods("GET")
-	router.HandleFunc("/favicon.ico", FavIcon(staticFolder)).Methods("GET")
 	// SPA
-	router.HandleFunc("/endpoints/{name}", SinglePageApplication(staticFolder, cfg.UI)).Methods("GET")
-	router.HandleFunc("/", SinglePageApplication(staticFolder, cfg.UI)).Methods("GET")
+	router.HandleFunc("/endpoints/{name}", SinglePageApplication(cfg.UI)).Methods("GET")
+	router.HandleFunc("/", SinglePageApplication(cfg.UI)).Methods("GET")
 	// Everything else falls back on static content
-	router.PathPrefix("/").Handler(GzipHandler(http.FileServer(http.Dir(staticFolder))))
+	staticFileSystem, err := fs.Sub(static.FileSystem, static.RootPath)
+	if err != nil {
+		panic(err)
+	}
+	router.PathPrefix("/").Handler(GzipHandler(http.FileServer(http.FS(staticFileSystem))))
 	return router
 }

controller/handler/handler_test.go

@@ -9,7 +9,7 @@ import (
 )
 
 func TestCreateRouter(t *testing.T) {
-	router := CreateRouter("../../web/static", &config.Config{Metrics: true})
+	router := CreateRouter(&config.Config{Metrics: true})
 	type Scenario struct {
 		Name         string
 		Path         string
@@ -28,16 +28,32 @@ func TestCreateRouter(t *testing.T) {
 			ExpectedCode: http.StatusOK,
 		},
 		{
-			Name:         "scripts",
+			Name:         "favicon.ico",
+			Path:         "/favicon.ico",
+			ExpectedCode: http.StatusOK,
+		},
+		{
+			Name:         "app.js",
 			Path:         "/js/app.js",
 			ExpectedCode: http.StatusOK,
 		},
 		{
-			Name:         "scripts-gzipped",
+			Name:         "app.js-gzipped",
 			Path:         "/js/app.js",
 			ExpectedCode: http.StatusOK,
 			Gzip:         true,
 		},
+		{
+			Name:         "chunk-vendors.js",
+			Path:         "/js/chunk-vendors.js",
+			ExpectedCode: http.StatusOK,
+		},
+		{
+			Name:         "chunk-vendors.js-gzipped",
+			Path:         "/js/chunk-vendors.js",
+			ExpectedCode: http.StatusOK,
+			Gzip:         true,
+		},
 		{
 			Name:         "index-redirect",
 			Path:         "/index.html",

controller/handler/spa.go

@@ -1,26 +1,30 @@
 package handler
 
 import (
+	_ "embed"
 	"html/template"
 	"log"
 	"net/http"
 
 	"github.com/TwiN/gatus/v4/config/ui"
+	"github.com/TwiN/gatus/v4/web"
 )
 
-func SinglePageApplication(staticFolder string, ui *ui.Config) http.HandlerFunc {
+func SinglePageApplication(ui *ui.Config) http.HandlerFunc {
 	return func(writer http.ResponseWriter, request *http.Request) {
-		t, err := template.ParseFiles(staticFolder + "/index.html")
+		t, err := template.ParseFS(static.FileSystem, static.IndexPath)
 		if err != nil {
-			log.Println("[handler][SinglePageApplication] Failed to parse template:", err.Error())
-			http.ServeFile(writer, request, staticFolder+"/index.html")
+			// This should never happen, because ui.ValidateAndSetDefaults validates that the template works.
+			log.Println("[handler][SinglePageApplication] Failed to parse template. This should never happen, because the template is validated on start. Error:", err.Error())
+			http.Error(writer, "Failed to parse template. This should never happen, because the template is validated on start.", http.StatusInternalServerError)
 			return
 		}
 		writer.Header().Set("Content-Type", "text/html")
 		err = t.Execute(writer, ui)
 		if err != nil {
-			log.Println("[handler][SinglePageApplication] Failed to parse template:", err.Error())
-			http.ServeFile(writer, request, staticFolder+"/index.html")
+			// This should never happen, because ui.ValidateAndSetDefaults validates that the template works.
+			log.Println("[handler][SinglePageApplication] Failed to execute template. This should never happen, because the template is validated on start. Error:", err.Error())
+			http.Error(writer, "Failed to execute template. This should never happen, because the template is validated on start.", http.StatusInternalServerError)
 			return
 		}
 	}

controller/handler/spa_test.go

@@ -30,7 +30,7 @@ func TestSinglePageApplication(t *testing.T) {
 	}
 	watchdog.UpdateEndpointStatuses(cfg.Endpoints[0], &core.Result{Success: true, Duration: time.Millisecond, Timestamp: time.Now()})
 	watchdog.UpdateEndpointStatuses(cfg.Endpoints[1], &core.Result{Success: false, Duration: time.Second, Timestamp: time.Now()})
-	router := CreateRouter("../../web/static", cfg)
+	router := CreateRouter(cfg)
 	type Scenario struct {
 		Name         string
 		Path         string

web/static.go

@@ -0,0 +1,13 @@
+package static
+
+import "embed"
+
+var (
+	//go:embed static
+	FileSystem embed.FS
+)
+
+const (
+	RootPath  = "static"
+	IndexPath = RootPath + "/index.html"
+)

web/static_test.go

@@ -0,0 +1,74 @@
+package static
+
+import (
+	"io/fs"
+	"strings"
+	"testing"
+)
+
+func TestEmbed(t *testing.T) {
+	scenarios := []struct {
+		path                  string
+		shouldExist           bool
+		expectedContainString string
+	}{
+		{
+			path:                  "index.html",
+			shouldExist:           true,
+			expectedContainString: "</body>",
+		},
+		{
+			path:                  "favicon.ico",
+			shouldExist:           true,
+			expectedContainString: "", // not checking because it's an image
+		},
+		{
+			path:                  "img/logo.svg",
+			shouldExist:           true,
+			expectedContainString: "</svg>",
+		},
+		{
+			path:                  "css/app.css",
+			shouldExist:           true,
+			expectedContainString: "background-color",
+		},
+		{
+			path:                  "js/app.js",
+			shouldExist:           true,
+			expectedContainString: "function",
+		},
+		{
+			path:                  "js/chunk-vendors.js",
+			shouldExist:           true,
+			expectedContainString: "function",
+		},
+		{
+			path:        "file-that-does-not-exist.html",
+			shouldExist: false,
+		},
+	}
+	staticFileSystem, err := fs.Sub(FileSystem, RootPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.path, func(t *testing.T) {
+			content, err := fs.ReadFile(staticFileSystem, scenario.path)
+			if !scenario.shouldExist {
+				if err == nil {
+					t.Errorf("%s should not have existed", scenario.path)
+				}
+			} else {
+				if err != nil {
+					t.Errorf("opening %s should not have returned an error, got %s", scenario.path, err.Error())
+				}
+				if len(content) == 0 {
+					t.Errorf("%s should have existed in the static FileSystem, but was empty", scenario.path)
+				}
+				if !strings.Contains(string(content), scenario.expectedContainString) {
+					t.Errorf("%s should have contained %s, but did not", scenario.path, scenario.expectedContainString)
+				}
+			}
+		})
+	}
+}