Serve Prysm Web UI from Validator (#7470)

* Prysm web UI basic idea

* Refactor to use shared.Service interface, add sanity test

* register web server

* Determine mimetype

* Use 4242 as port for web

* Allow localhost or 127.0.0.1 for CORS. More tests, commentary

* Add flags, add site_data.go

* ignore site data

* Add sha

* gofmt

* gofmt

* fix script

* Lints

* fix vis

Co-authored-by: Victor Farazdagi <simple.square@gmail.com>

validator/web/BUILD.bazel

@@ -0,0 +1,35 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_test")
+load("@prysm//tools/go:def.bzl", "go_library")
+load("@io_bazel_rules_go//extras:embed_data.bzl", "go_embed_data")
+
+# gazelle:ignore site_data.go
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "doc.go",
+        "handler.go",
+        "server.go",
+        ":site_data",  # keep
+    ],
+    importpath = "github.com/prysmaticlabs/prysm/validator/web",
+    visibility = ["//validator:__subpackages__"],
+    deps = [
+        "//shared:go_default_library",
+        "@com_github_sirupsen_logrus//:go_default_library",
+    ],
+)
+
+go_embed_data(
+    name = "site_data",
+    srcs = [
+        "@prysm_web_ui//:site",
+    ],
+    var = "site",
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["handler_test.go"],
+    embed = [":go_default_library"],
+    deps = ["//shared/testutil/assert:go_default_library"],
+)

validator/web/doc.go

@@ -0,0 +1,2 @@
+// Package web is the service to serve the Prysm web UI. See https://github.com/prysmaticlabs/prysm-web-ui
+package web

validator/web/handler.go

@@ -0,0 +1,49 @@
+package web
+
+import (
+	"mime"
+	"net/http"
+	"net/url"
+	"path"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const prefix = "external/prysm_web_ui"
+
+// webHandler serves web requests from the bundled site data.
+var webHandler = func(res http.ResponseWriter, req *http.Request) {
+	u, err := url.ParseRequestURI(req.RequestURI)
+	if err != nil {
+		panic(err)
+	}
+	p := u.Path
+	if p == "/" {
+		p = "/index.html"
+	}
+	p = path.Join(prefix, p)
+
+	if d, ok := site[p]; ok {
+		m := mime.TypeByExtension(path.Ext(p))
+		res.Header().Add("Content-Type", m)
+		res.WriteHeader(200)
+		if _, err := res.Write(d); err != nil {
+			log.WithError(err).Error("Failed to write http response")
+		}
+	} else if d, ok := site[path.Join(prefix, "index.html")]; ok {
+		// Angular routing expects that routes are rewritten to serve index.html. For example, if
+		// requesting /login, this should serve the single page app index.html.
+		m := mime.TypeByExtension(".html")
+		res.Header().Add("Content-Type", m)
+		res.WriteHeader(200)
+		if _, err := res.Write(d); err != nil {
+			log.WithError(err).Error("Failed to write http response")
+		}
+	} else { // If index.html is not present, serve 404. This should never happen.
+		log.WithField("URI", req.RequestURI).Error("Path not found")
+		res.WriteHeader(404)
+		if _, err := res.Write([]byte("Not found")); err != nil {
+			log.WithError(err).Error("Failed to write http response")
+		}
+	}
+}

validator/web/handler_test.go

@@ -0,0 +1,53 @@
+package web
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
+)
+
+func TestWebHandler(t *testing.T) {
+	tests := []struct {
+		name            string
+		requestURI      string
+		wantStatus      int
+		wantContentType string
+	}{
+		{
+			name:            "base route",
+			requestURI:      "/",
+			wantStatus:      200,
+			wantContentType: "text/html; charset=utf-8",
+		},
+		{
+			name:            "index.html",
+			requestURI:      "/index.html",
+			wantStatus:      200,
+			wantContentType: "text/html; charset=utf-8",
+		},
+		{
+			name:            "bad route",
+			requestURI:      "/foobar_bad",
+			wantStatus:      200, // Serves index.html by default.
+			wantContentType: "text/html; charset=utf-8",
+		},
+		{
+			name:            "favicon.ico",
+			requestURI:      "/favicon.ico",
+			wantStatus:      200,
+			wantContentType: "image/vnd.microsoft.icon",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			req := &http.Request{RequestURI: tt.requestURI}
+			res := httptest.NewRecorder()
+			webHandler(res, req)
+			assert.Equal(t, tt.wantStatus, res.Result().StatusCode)
+			assert.Equal(t, tt.wantContentType, res.Result().Header.Get("Content-Type"))
+		})
+	}
+}

validator/web/server.go

@@ -0,0 +1,52 @@
+package web
+
+import (
+	"context"
+	"net/http"
+	"time"
+
+	"github.com/prysmaticlabs/prysm/shared"
+	log "github.com/sirupsen/logrus"
+)
+
+var _ = shared.Service(&Server{})
+
+// Server for the Prysm Web UI.
+type Server struct {
+	http *http.Server
+}
+
+// NewServer creates a server service for the Prysm web UI.
+func NewServer(addr string) *Server {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/", webHandler)
+
+	return &Server{
+		http: &http.Server{
+			Addr:    addr,
+			Handler: mux,
+		},
+	}
+}
+
+// Start the web server.
+func (s *Server) Start() {
+	go func() {
+		log.WithField("address", s.http.Addr).Info("Starting Prysm web UI")
+		if err := s.http.ListenAndServe(); err != nil {
+			log.WithError(err).Error("Failed to start validator web server")
+		}
+	}()
+}
+
+// Stop the web server gracefully with 1s timeout.
+func (s *Server) Stop() error {
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+	defer cancel()
+	return s.http.Shutdown(ctx)
+}
+
+// Status check for web server. Always returns nil.
+func (s *Server) Status() error {
+	return nil
+}