chore(cmd): clean up commands (#9705)

Move infrastructure related commands to under `cmd/infra` and
development stuff to `cmd/dev`. The default build command builds the
regular user facing binaries: syncthing, stdiscosrv, and strelaysrv.

cmd/infra/stupgrades/main.go

@@ -0,0 +1,171 @@
+// Copyright (C) 2019 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/alecthomas/kong"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	_ "github.com/syncthing/syncthing/lib/automaxprocs"
+	"github.com/syncthing/syncthing/lib/httpcache"
+	"github.com/syncthing/syncthing/lib/upgrade"
+)
+
+type cli struct {
+	Listen        string        `default:":8080" help:"Listen address"`
+	MetricsListen string        `default:":8081" help:"Listen address for metrics"`
+	URL           string        `short:"u" default:"https://api.github.com/repos/syncthing/syncthing/releases?per_page=25" help:"GitHub releases url"`
+	Forward       []string      `short:"f" help:"Forwarded pages, format: /path->https://example/com/url"`
+	CacheTime     time.Duration `default:"15m" help:"Cache time"`
+}
+
+func main() {
+	var params cli
+	kong.Parse(&params)
+	if err := server(&params); err != nil {
+		fmt.Printf("Error: %v\n", err)
+		os.Exit(1)
+	}
+}
+
+func server(params *cli) error {
+	if params.MetricsListen != "" {
+		mux := http.NewServeMux()
+		mux.Handle("/metrics", promhttp.Handler())
+		go func() {
+			log.Println("Listening for metrics on", params.MetricsListen)
+			if err := http.ListenAndServe(params.MetricsListen, mux); err != nil {
+				log.Fatalf("Failed to start metrics server: %v", err)
+			}
+		}()
+	}
+
+	mux := http.NewServeMux()
+	mux.Handle("/meta.json", httpcache.SinglePath(&githubReleases{url: params.URL}, params.CacheTime))
+
+	for _, fwd := range params.Forward {
+		path, url, ok := strings.Cut(fwd, "->")
+		if !ok {
+			return fmt.Errorf("invalid forward: %q", fwd)
+		}
+		log.Println("Forwarding", path, "to", url)
+		mux.Handle(path, httpcache.SinglePath(&proxy{url: url}, params.CacheTime))
+	}
+
+	srv := &http.Server{
+		Addr:         params.Listen,
+		Handler:      mux,
+		ReadTimeout:  5 * time.Second,
+		WriteTimeout: 10 * time.Second,
+	}
+	srv.SetKeepAlivesEnabled(false)
+	return srv.ListenAndServe()
+}
+
+type githubReleases struct {
+	url string
+}
+
+func (p *githubReleases) ServeHTTP(w http.ResponseWriter, _ *http.Request) {
+	log.Println("Fetching", p.url)
+	rels := upgrade.FetchLatestReleases(p.url, "")
+	if rels == nil {
+		http.Error(w, "no releases", http.StatusInternalServerError)
+		return
+	}
+
+	sort.Sort(upgrade.SortByRelease(rels))
+	rels = filterForLatest(rels)
+
+	// Move the URL used for browser downloads to the URL field, and remove
+	// the browser URL field. This avoids going via the GitHub API for
+	// downloads, since Syncthing uses the URL field.
+	for _, rel := range rels {
+		for j, asset := range rel.Assets {
+			rel.Assets[j].URL = asset.BrowserURL
+			rel.Assets[j].BrowserURL = ""
+		}
+	}
+
+	buf := new(bytes.Buffer)
+	_ = json.NewEncoder(buf).Encode(rels)
+
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Access-Control-Allow-Origin", "*")
+	w.Header().Set("Access-Control-Allow-Methods", "GET")
+	w.Write(buf.Bytes())
+}
+
+type proxy struct {
+	url string
+}
+
+func (p *proxy) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	log.Println("Fetching", p.url)
+	req, err := http.NewRequestWithContext(req.Context(), http.MethodGet, p.url, nil)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	defer resp.Body.Close()
+
+	ct := resp.Header.Get("Content-Type")
+	w.Header().Set("Content-Type", ct)
+	if resp.StatusCode == http.StatusOK {
+		w.Header().Set("Cache-Control", "public, max-age=900")
+		w.Header().Set("Access-Control-Allow-Origin", "*")
+		w.Header().Set("Access-Control-Allow-Methods", "GET")
+	}
+	w.WriteHeader(resp.StatusCode)
+	if strings.HasPrefix(ct, "application/json") {
+		// Special JSON handling; clean it up a bit.
+		var v interface{}
+		if err := json.NewDecoder(resp.Body).Decode(&v); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		_ = json.NewEncoder(w).Encode(v)
+	} else {
+		_, _ = io.Copy(w, resp.Body)
+	}
+}
+
+// filterForLatest returns the latest stable and prerelease only. If the
+// stable version is newer (comes first in the list) there is no need to go
+// looking for a prerelease at all.
+func filterForLatest(rels []upgrade.Release) []upgrade.Release {
+	var filtered []upgrade.Release
+	var havePre bool
+	for _, rel := range rels {
+		if !rel.Prerelease {
+			// We found a stable version, we're good now.
+			filtered = append(filtered, rel)
+			break
+		}
+		if rel.Prerelease && !havePre {
+			// We remember the first prerelease we find.
+			filtered = append(filtered, rel)
+			havePre = true
+		}
+	}
+	return filtered
+}