cmd/pkgsite: add command

Functionality for running the pkgsite frontend locally is moved from
cmd/frontend to cmd/pkgsite, since cmd/frontend is currently overloaded
with flag options and running locally does not need all the dependencies
for running cmd/frontend.

Additional functionality will be added to cmd/pkgsite in future CLs.

For golang/go#40371

Change-Id: I4230aa9539c94e01a68eda33cc6492ae377debff
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/290134
Reviewed-by: Jamal Carvalho <jamal@golang.org>
Trust: Julie Qiu <julie@golang.org>

1 files changed, 99 insertions, 0 deletions

diff --git a/cmd/pkgsite/main.go b/cmd/pkgsite/main.go
new file mode 100644
index 00000000..bfb1b0a3
--- /dev/null
+++ b/cmd/pkgsite/main.go
@@ -0,0 +1,99 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This is a work in progress.
+//
+// Pkgsite extracts and generates documentation for Go programs.
+// It runs as a web server and presents the documentation as a
+// web page.
+// Usage:
+//
+//  pkgsite [flag]
+//
+// The flags are:
+//
+//  -local=path1,path2
+//      Accepts a GOPATH-like collection of local paths for modules to load to memory
+//  -gopath_mode=false
+//      Assume that local modules' paths are relative to GOPATH/src
+package main
+
+import (
+	"context"
+	"flag"
+	"net/http"
+	"path/filepath"
+	"time"
+
+	"github.com/google/safehtml/template"
+	"golang.org/x/pkgsite/internal"
+	"golang.org/x/pkgsite/internal/dcensus"
+	"golang.org/x/pkgsite/internal/frontend"
+	"golang.org/x/pkgsite/internal/localdatasource"
+	"golang.org/x/pkgsite/internal/log"
+	"golang.org/x/pkgsite/internal/middleware"
+)
+
+var (
+	_          = flag.String("static", "content/static", "path to folder containing static files served")
+	localPaths = flag.String("local", "", "run locally, accepts a GOPATH-like collection of local paths for modules to load to memory")
+	gopathMode = flag.Bool("gopath_mode", false, "assume that local modules' paths are relative to GOPATH/src, used only with -local")
+)
+
+func main() {
+	flag.Parse()
+	ctx := context.Background()
+	var dsg func(context.Context) internal.DataSource
+	if *localPaths == "" {
+		log.Fatalf(ctx, "-local is not set")
+	}
+
+	lds := localdatasource.New()
+	dsg = func(context.Context) internal.DataSource { return lds }
+	server, err := frontend.NewServer(frontend.ServerConfig{
+		DataSourceGetter: dsg,
+		StaticPath:       template.TrustedSourceFromFlag(flag.Lookup("static").Value),
+	})
+	if err != nil {
+		log.Fatalf(ctx, "frontend.NewServer: %v", err)
+	}
+	lds, ok := dsg(ctx).(*localdatasource.DataSource)
+	if ok {
+		load(ctx, lds, *localPaths)
+	}
+
+	router := dcensus.NewRouter(frontend.TagRoute)
+	server.Install(router.Handle, nil, nil)
+
+	mw := middleware.Chain(
+		middleware.RedirectedFrom(),
+		middleware.LatestVersions(server.GetLatestInfo), // must come before caching for version badge to work
+		middleware.Timeout(54*time.Second),
+	)
+	addr := "localhost:6060"
+	log.Infof(ctx, "Listening on addr %s", addr)
+	log.Fatal(ctx, http.ListenAndServe(addr, mw(router)))
+}
+
+// load loads local modules from pathList.
+func load(ctx context.Context, ds *localdatasource.DataSource, pathList string) {
+	paths := filepath.SplitList(pathList)
+	loaded := len(paths)
+	for _, path := range paths {
+		var err error
+		if *gopathMode {
+			err = ds.LoadFromGOPATH(ctx, path)
+		} else {
+			err = ds.Load(ctx, path)
+		}
+		if err != nil {
+			log.Error(ctx, err)
+			loaded--
+		}
+	}
+
+	if loaded == 0 {
+		log.Fatalf(ctx, "failed to load module(s) at %s", pathList)
+	}
+}