Implement new Go based Desktop app

This focuses on Windows first, but coudl be used for Mac
and possibly linux in the future.

app/lifecycle/updater.go

@@ -0,0 +1,216 @@
+package lifecycle
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"log/slog"
+	"mime"
+	"net/http"
+	"os"
+	"path"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"time"
+
+	"github.com/jmorganca/ollama/auth"
+	"github.com/jmorganca/ollama/version"
+)
+
+var (
+	UpdateCheckURLBase = "https://ollama.ai/api/update"
+	UpdateDownloaded   = false
+)
+
+// TODO - maybe move up to the API package?
+type UpdateResponse struct {
+	UpdateURL     string `json:"url"`
+	UpdateVersion string `json:"version"`
+}
+
+func getClient(req *http.Request) http.Client {
+	proxyURL, err := http.ProxyFromEnvironment(req)
+	if err != nil {
+		slog.Warn(fmt.Sprintf("failed to handle proxy: %s", err))
+		return http.Client{}
+	}
+
+	return http.Client{
+		Transport: &http.Transport{
+			Proxy: http.ProxyURL(proxyURL),
+		},
+	}
+}
+
+func IsNewReleaseAvailable(ctx context.Context) (bool, UpdateResponse) {
+	var updateResp UpdateResponse
+	updateCheckURL := UpdateCheckURLBase + "?os=" + runtime.GOOS + "&arch=" + runtime.GOARCH + "&version=" + version.Version
+	headers := make(http.Header)
+	err := auth.SignRequest(http.MethodGet, updateCheckURL, nil, headers)
+	if err != nil {
+		slog.Info(fmt.Sprintf("failed to sign update request %s", err))
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, updateCheckURL, nil)
+	if err != nil {
+		slog.Warn(fmt.Sprintf("failed to check for update: %s", err))
+		return false, updateResp
+	}
+	req.Header = headers
+	req.Header.Set("User-Agent", fmt.Sprintf("ollama/%s (%s %s) Go/%s", version.Version, runtime.GOARCH, runtime.GOOS, runtime.Version()))
+	client := getClient(req)
+
+	slog.Debug(fmt.Sprintf("checking for available update at %s with headers %v", updateCheckURL, headers))
+	resp, err := client.Do(req)
+	if err != nil {
+		slog.Warn(fmt.Sprintf("failed to check for update: %s", err))
+		return false, updateResp
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode == 204 {
+		slog.Debug("check update response 204 (current version is up to date)")
+		return false, updateResp
+	}
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		slog.Warn(fmt.Sprintf("failed to read body response: %s", err))
+	}
+	err = json.Unmarshal(body, &updateResp)
+	if err != nil {
+		slog.Warn(fmt.Sprintf("malformed response checking for update: %s", err))
+		return false, updateResp
+	}
+	// Extract the version string from the URL in the github release artifact path
+	updateResp.UpdateVersion = path.Base(path.Dir(updateResp.UpdateURL))
+
+	slog.Info("New update available at " + updateResp.UpdateURL)
+	return true, updateResp
+}
+
+// Returns true if we downloaded a new update, false if we already had it
+func DownloadNewRelease(ctx context.Context, updateResp UpdateResponse) error {
+	// Do a head first to check etag info
+	req, err := http.NewRequestWithContext(ctx, http.MethodHead, updateResp.UpdateURL, nil)
+	if err != nil {
+		return err
+	}
+	client := getClient(req)
+	resp, err := client.Do(req)
+	if err != nil {
+		return fmt.Errorf("error checking update: %w", err)
+	}
+	if resp.StatusCode != 200 {
+		return fmt.Errorf("unexpected status attempting to download update %d", resp.StatusCode)
+	}
+	resp.Body.Close()
+	etag := strings.Trim(resp.Header.Get("etag"), "\"")
+	if etag == "" {
+		slog.Debug("no etag detected, falling back to filename based dedup")
+		etag = "_"
+	}
+	filename := Installer
+	_, params, err := mime.ParseMediaType(resp.Header.Get("content-disposition"))
+	if err == nil {
+		filename = params["filename"]
+	}
+
+	stageFilename := filepath.Join(UpdateStageDir, etag, filename)
+
+	// Check to see if we already have it downloaded
+	_, err = os.Stat(stageFilename)
+	if err == nil {
+		slog.Debug("update already downloaded")
+		return nil
+	}
+
+	cleanupOldDownloads()
+
+	req.Method = http.MethodGet
+	resp, err = client.Do(req)
+	if err != nil {
+		return fmt.Errorf("error checking update: %w", err)
+	}
+	defer resp.Body.Close()
+	etag = strings.Trim(resp.Header.Get("etag"), "\"")
+	if etag == "" {
+		slog.Debug("no etag detected, falling back to filename based dedup") // TODO probably can get rid of this redundant log
+		etag = "_"
+	}
+
+	stageFilename = filepath.Join(UpdateStageDir, etag, filename)
+
+	_, err = os.Stat(filepath.Dir(stageFilename))
+	if errors.Is(err, os.ErrNotExist) {
+		if err := os.MkdirAll(filepath.Dir(stageFilename), 0o755); err != nil {
+			return fmt.Errorf("create ollama dir %s: %v", filepath.Dir(stageFilename), err)
+		}
+	}
+
+	payload, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("failed to read body response: %w", err)
+	}
+	fp, err := os.OpenFile(stageFilename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0o755)
+	if err != nil {
+		return fmt.Errorf("write payload %s: %w", stageFilename, err)
+	}
+	defer fp.Close()
+	if n, err := fp.Write(payload); err != nil || n != len(payload) {
+		return fmt.Errorf("write payload %s: %d vs %d -- %w", stageFilename, n, len(payload), err)
+	}
+	slog.Info("new update downloaded " + stageFilename)
+
+	UpdateDownloaded = true
+	return nil
+}
+
+func cleanupOldDownloads() {
+	files, err := os.ReadDir(UpdateStageDir)
+	if err != nil && errors.Is(err, os.ErrNotExist) {
+		// Expected behavior on first run
+		return
+	} else if err != nil {
+		slog.Warn(fmt.Sprintf("failed to list stage dir: %s", err))
+		return
+	}
+	for _, file := range files {
+		fullname := filepath.Join(UpdateStageDir, file.Name())
+		slog.Debug("cleaning up old download: " + fullname)
+		err = os.RemoveAll(fullname)
+		if err != nil {
+			slog.Warn(fmt.Sprintf("failed to cleanup stale update download %s", err))
+		}
+	}
+}
+
+func StartBackgroundUpdaterChecker(ctx context.Context, cb func(string) error) {
+	go func() {
+		// Don't blast an update message immediately after startup
+		// time.Sleep(30 * time.Second)
+		time.Sleep(3 * time.Second)
+
+		for {
+			available, resp := IsNewReleaseAvailable(ctx)
+			if available {
+				err := DownloadNewRelease(ctx, resp)
+				if err != nil {
+					slog.Error(fmt.Sprintf("failed to download new release: %s", err))
+				}
+				err = cb(resp.UpdateVersion)
+				if err != nil {
+					slog.Warn(fmt.Sprintf("failed to register update available with tray: %s", err))
+				}
+			}
+			select {
+			case <-ctx.Done():
+				slog.Debug("stopping background update checker")
+				return
+			default:
+				time.Sleep(60 * 60 * time.Second)
+			}
+		}
+	}()
+}