feat(updates): add host updater engine

Author: mcharles-square

server/cmd/fleet-updater/main.go

@@ -0,0 +1,83 @@
+package main
+
+import (
+	"errors"
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"os/signal"
+	"path/filepath"
+	"syscall"
+
+	"github.com/block/proto-fleet/server/internal/updater"
+)
+
+var version = "dev"
+
+func main() {
+	defaultInstallRoot := os.Getenv("PROTO_FLEET_INSTALL_ROOT")
+	if defaultInstallRoot == "" {
+		defaultInstallRoot = "/opt/proto-fleet"
+	}
+	defaultStateDir := os.Getenv("PROTO_FLEET_UPDATER_STATE_DIR")
+	if defaultStateDir == "" {
+		defaultStateDir = "/var/lib/proto-fleet-updater"
+	}
+	defaultSocketPath := os.Getenv("PROTO_FLEET_UPDATER_SOCKET_PATH")
+	if defaultSocketPath == "" {
+		defaultSocketPath = "/run/proto-fleet-updater/updater.sock"
+	}
+	defaultDownloadBase := os.Getenv("PROTO_FLEET_DOWNLOAD_BASE_URL")
+	if defaultDownloadBase == "" {
+		defaultDownloadBase = "https://github.com/block/proto-fleet/releases/download"
+	}
+	defaultSelfUpdatePath := os.Getenv("PROTO_FLEET_UPDATER_BINARY_PATH")
+
+	installRoot := flag.String("install-root", defaultInstallRoot, "Proto Fleet installation root")
+	stateDir := flag.String("state-dir", defaultStateDir, "Durable updater state directory")
+	socketPath := flag.String("socket-path", defaultSocketPath, "Unix socket path")
+	downloadBase := flag.String("download-base-url", defaultDownloadBase, "Official release download base URL")
+	selfUpdatePath := flag.String("self-update-path", defaultSelfUpdatePath, "Installed updater binary path to atomically refresh")
+	showVersion := flag.Bool("version", false, "Print version and exit")
+	flag.Parse()
+
+	if *showVersion {
+		fmt.Println(version)
+		return
+	}
+	absoluteInstallRoot, err := filepath.Abs(*installRoot)
+	if err != nil {
+		log.Fatal(err)
+	}
+	manager, err := updater.NewManager(updater.Config{
+		InstallRoot:     absoluteInstallRoot,
+		StateDir:        *stateDir,
+		DownloadBaseURL: *downloadBase,
+		SelfUpdatePath:  *selfUpdatePath,
+	})
+	if err != nil {
+		log.Fatalf("initialize updater: %v", err)
+	}
+	server := updater.NewServer(manager)
+	errs := make(chan error, 1)
+	go func() {
+		log.Printf("proto-fleet-updater %s listening on %s", version, *socketPath)
+		errs <- server.Serve(*socketPath)
+	}()
+
+	signals := make(chan os.Signal, 1)
+	signal.Notify(signals, syscall.SIGINT, syscall.SIGTERM)
+	select {
+	case sig := <-signals:
+		log.Printf("received %s, shutting down", sig)
+		if err := server.Shutdown(); err != nil {
+			log.Printf("shutdown: %v", err)
+		}
+	case err := <-errs:
+		if !errors.Is(err, http.ErrServerClosed) {
+			log.Fatalf("serve updater API: %v", err)
+		}
+	}
+}