feat: [CODE-2565]: Add development config to support alternate UI source (#2848) (#3212)

app/router/secure.go

@@ -0,0 +1,45 @@
+// Copyright 2023 Harness, 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 router
+
+import (
+	"github.com/harness/gitness/types"
+
+	"github.com/unrolled/secure"
+)
+
+// NewSecure returns a new secure.Secure middleware to enforce security best practices
+// for the user interface (not meant APIs).
+func NewSecure(config *types.Config) *secure.Secure {
+	return secure.New(
+		secure.Options{
+			AllowedHosts:          config.Secure.AllowedHosts,
+			HostsProxyHeaders:     config.Secure.HostsProxyHeaders,
+			SSLRedirect:           config.Secure.SSLRedirect,
+			SSLTemporaryRedirect:  config.Secure.SSLTemporaryRedirect,
+			SSLHost:               config.Secure.SSLHost,
+			SSLProxyHeaders:       config.Secure.SSLProxyHeaders,
+			STSSeconds:            config.Secure.STSSeconds,
+			STSIncludeSubdomains:  config.Secure.STSIncludeSubdomains,
+			STSPreload:            config.Secure.STSPreload,
+			ForceSTSHeader:        config.Secure.ForceSTSHeader,
+			FrameDeny:             config.Secure.FrameDeny,
+			ContentTypeNosniff:    config.Secure.ContentTypeNosniff,
+			BrowserXssFilter:      config.Secure.BrowserXSSFilter,
+			ContentSecurityPolicy: config.Secure.ContentSecurityPolicy,
+			ReferrerPolicy:        config.Secure.ReferrerPolicy,
+		},
+	)
+}

app/router/web.go

@@ -21,7 +21,6 @@ import (
 	"github.com/harness/gitness/app/api/openapi"
 	"github.com/harness/gitness/app/api/render"
 	"github.com/harness/gitness/app/auth/authn"
-	"github.com/harness/gitness/types"
 	"github.com/harness/gitness/web"
 
 	"github.com/go-chi/chi/v5"
@@ -33,34 +32,14 @@ import (
 
 // NewWebHandler returns a new WebHandler.
 func NewWebHandler(
-	config *types.Config,
 	authenticator authn.Authenticator,
 	openapi openapi.Service,
+	sec *secure.Secure,
+	publicResourceCreationEnabled bool,
+	uiSourceOverride string,
 ) http.Handler {
 	// Use go-chi router for inner routing
 	r := chi.NewRouter()
-	// create middleware to enforce security best practices for
-	// the user interface. note that theis middleware is only used
-	// when serving the user interface (not found handler, below).
-	sec := secure.New(
-		secure.Options{
-			AllowedHosts:          config.Secure.AllowedHosts,
-			HostsProxyHeaders:     config.Secure.HostsProxyHeaders,
-			SSLRedirect:           config.Secure.SSLRedirect,
-			SSLTemporaryRedirect:  config.Secure.SSLTemporaryRedirect,
-			SSLHost:               config.Secure.SSLHost,
-			SSLProxyHeaders:       config.Secure.SSLProxyHeaders,
-			STSSeconds:            config.Secure.STSSeconds,
-			STSIncludeSubdomains:  config.Secure.STSIncludeSubdomains,
-			STSPreload:            config.Secure.STSPreload,
-			ForceSTSHeader:        config.Secure.ForceSTSHeader,
-			FrameDeny:             config.Secure.FrameDeny,
-			ContentTypeNosniff:    config.Secure.ContentTypeNosniff,
-			BrowserXssFilter:      config.Secure.BrowserXSSFilter,
-			ContentSecurityPolicy: config.Secure.ContentSecurityPolicy,
-			ReferrerPolicy:        config.Secure.ReferrerPolicy,
-		},
-	)
 
 	// openapi endpoints
 	// TODO: this should not be generated and marshaled on the fly every time?
@@ -102,9 +81,9 @@ func NewWebHandler(
 	// which in turn serves the user interface.
 	r.With(
 		sec.Handler,
-		middlewareweb.PublicAccess(config.PublicResourceCreationEnabled, authenticator),
+		middlewareweb.PublicAccess(publicResourceCreationEnabled, authenticator),
 	).NotFound(
-		web.Handler(),
+		web.Handler(uiSourceOverride),
 	)
 
 	return r

app/router/wire.go

@@ -136,7 +136,12 @@ func ProvideRouter(
 		infraProviderCtrl, migrateCtrl, gitspaceCtrl, aiagentCtrl, capabilitiesCtrl, usageSender)
 	routers[2] = NewAPIRouter(apiHandler)
 
-	webHandler := NewWebHandler(config, authenticator, openapi)
+	sec := NewSecure(config)
+	webHandler := NewWebHandler(
+		authenticator, openapi, sec,
+		config.PublicResourceCreationEnabled,
+		config.Development.UISourceOverride,
+	)
 	routers[3] = NewWebRouter(webHandler)
 
 	return NewRouter(routers)

types/config.go

@@ -507,4 +507,8 @@ type Config struct {
 		ChunkSize  string `envconfig:"GITNESS_USAGE_METRICS_CHUNK_SIZE" default:"10MiB"`
 		MaxWorkers int    `envconfig:"GITNESS_USAGE_METRICS_MAX_WORKERS" default:"50"`
 	}
+
+	Development struct {
+		UISourceOverride string `envconfig:"GITNESS_DEVELOPMENT_UI_SOURCE_OVERRIDE"`
+	}
 }

web/dist.go

@@ -19,6 +19,7 @@ import (
 	"bytes"
 	"context"
 	"embed"
+	"errors"
 	"fmt"
 	"io"
 	"io/fs"
@@ -26,45 +27,64 @@ import (
 	"os"
 	"path"
 	"time"
+
+	"github.com/rs/zerolog/log"
 )
 
 //go:embed dist/*
-var UI embed.FS
-var remoteEntryContent []byte
-var fileMap map[string]bool
+var EmbeddedUIFS embed.FS
 
-const distPath = "dist"
-const remoteEntryJS = "remoteEntry.js"
-const remoteEntryJSFullPath = "/" + remoteEntryJS
+const (
+	distPath              = "dist"
+	remoteEntryJS         = "remoteEntry.js"
+	remoteEntryJSFullPath = "/" + remoteEntryJS
+)
 
 // Handler returns an http.HandlerFunc that servers the
 // static content from the embedded file system.
 //
 //nolint:gocognit // refactor if required.
-func Handler() http.HandlerFunc {
-	// Load the files subdirectory
-	fs, err := fs.Sub(UI, distPath)
+func Handler(uiSourceOverride string) http.HandlerFunc {
+	fs, err := fs.Sub(EmbeddedUIFS, distPath)
 	if err != nil {
-		panic(err)
+		panic(fmt.Errorf("failed to load embedded files: %w", err))
 	}
 
-	// Create an http.FileServer to serve the
-	// contents of the files subdiretory.
+	// override UI source if provided (for local development)
+	if uiSourceOverride != "" {
+		log.Info().Msgf("Starting with alternate UI located at %q", uiSourceOverride)
+		fs = os.DirFS(uiSourceOverride)
+	}
+
+	remoteEntryContent, remoteEntryExists, err := readRemoteEntryJSContent(fs)
+	if err != nil {
+		panic(fmt.Errorf("failed to read remote entry JS content: %w", err))
+	}
+
+	fileMap, err := createFileMapForDistFolder(fs)
+	if err != nil {
+		panic(fmt.Errorf("failed to create file map for dist folder: %w", err))
+	}
+
+	publicIndexFileExists := fileMap["index_public.html"]
+
+	// Create an http.FileServer to serve the contents of the files subdiretory.
 	handler := http.FileServer(http.FS(fs))
 
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		// Get the file base path
 		basePath := path.Base(r.URL.Path)
 
-		// If the file exists in dist/ then serve it from "/".
-		// Otherwise, rewrite the request to "/" so /index.html is served
-		if fileNotFoundInDist(basePath) {
+		// fallback to root in case the file doesn't exist so /index.html is served
+		if !fileMap[basePath] {
 			r.URL.Path = "/"
 		} else {
 			r.URL.Path = "/" + basePath
 		}
 
-		if RenderPublicAccessFrom(r.Context()) &&
+		// handle public access
+		if publicIndexFileExists &&
+			RenderPublicAccessFrom(r.Context()) &&
 			(r.URL.Path == "/" || r.URL.Path == "/index.html") {
 			r.URL.Path = "/index_public.html"
 		}
@@ -80,7 +100,7 @@ func Handler() http.HandlerFunc {
 		}
 
 		// Serve /remoteEntry.js from memory
-		if r.URL.Path == remoteEntryJSFullPath {
+		if remoteEntryExists && r.URL.Path == remoteEntryJSFullPath {
 			http.ServeContent(w, r, r.URL.Path, time.Now(), bytes.NewReader(remoteEntryContent))
 		} else {
 			handler.ServeHTTP(w, r)
@@ -88,36 +108,19 @@ func Handler() http.HandlerFunc {
 	})
 }
 
-func init() {
-	err := readRemoteEntryJSContent()
-	if err != nil {
-		panic(err)
+func readRemoteEntryJSContent(fileSystem fs.FS) ([]byte, bool, error) {
+	file, err := fileSystem.Open(remoteEntryJS)
+	if errors.Is(err, os.ErrNotExist) {
+		return nil, false, nil
 	}
-
-	err = createFileMapForDistFolder()
 	if err != nil {
-		panic(err)
+		return nil, false, fmt.Errorf("failed to open remoteEntry.js: %w", err)
 	}
-}
-
-func readRemoteEntryJSContent() error {
-	fs, err := fs.Sub(UI, distPath)
-
-	if err != nil {
-		return fmt.Errorf("failed to open /dist: %w", err)
-	}
-
-	file, err := fs.Open(remoteEntryJS)
-
-	if err != nil {
-		return fmt.Errorf("failed to open remoteEntry.js: %w", err)
-	}
-
 	defer file.Close()
-	buf, err := io.ReadAll(file)
 
+	buf, err := io.ReadAll(file)
 	if err != nil {
-		return fmt.Errorf("failed to read remoteEntry.js: %w", err)
+		return nil, false, fmt.Errorf("failed to read remoteEntry.js: %w", err)
 	}
 
 	enableCDN := os.Getenv("ENABLE_CDN")
@@ -126,31 +129,28 @@ func readRemoteEntryJSContent() error {
 		enableCDN = "false"
 	}
 
-	remoteEntryContent = bytes.Replace(buf, []byte("__ENABLE_CDN__"), []byte(enableCDN), 1)
-
-	return nil
+	return bytes.Replace(buf, []byte("__ENABLE_CDN__"), []byte(enableCDN), 1), true, nil
 }
 
-func createFileMapForDistFolder() error {
-	fileMap = make(map[string]bool)
+func createFileMapForDistFolder(fileSystem fs.FS) (map[string]bool, error) {
+	fileMap := make(map[string]bool)
 
-	err := fs.WalkDir(UI, distPath, func(path string, _ fs.DirEntry, err error) error {
+	err := fs.WalkDir(fileSystem, ".", func(path string, _ fs.DirEntry, err error) error {
 		if err != nil {
-			return fmt.Errorf("failed to build file map for path %q: %w", path, err)
+			return fmt.Errorf("failed to read file info for %q: %w", path, err)
 		}
 
-		if path != distPath { // exclude "dist" from file map
+		if path != "." {
 			fileMap[path] = true
 		}
 
 		return nil
 	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to build file map: %w", err)
+	}
 
-	return err
-}
-
-func fileNotFoundInDist(path string) bool {
-	return !fileMap[distPath+"/"+path]
+	return fileMap, nil
 }
 
 // renderPublicAccessKey is the context key for storing and retrieving whether public access should be rendered.