Dockerfile: Add sidecar support

Author: saleemrashid

Dockerfile

@@ -10,8 +10,11 @@ RUN --mount=type=cache,target=/root/.cache/go-build \
 	--mount=type=cache,target=/go/pkg \
 	go build -ldflags "-s -w -X 'main.Version=${LITEFS_VERSION}' -X 'main.Commit=${LITEFS_COMMIT}' -extldflags '-static'" -tags osusergo,netgo,sqlite_omit_load_extension -o /usr/local/bin/litefs ./cmd/litefs
 
+FROM alpine
+
+RUN apk add --no-cache fuse3
 
-FROM scratch
 COPY --from=builder /usr/local/bin/litefs /usr/local/bin/litefs
+
 ENTRYPOINT ["/usr/local/bin/litefs"]
-CMD []
+CMD ["mount", "-no-unmount"]

cmd/litefs/mount_linux.go

@@ -31,8 +31,9 @@ import (
 
 // MountCommand represents a command to mount the file system.
 type MountCommand struct {
-	cmd    *exec.Cmd  // subcommand
-	execCh chan error // subcommand error channel
+	cmd       *exec.Cmd  // subcommand
+	execCh    chan error // subcommand error channel
+	noUnmount bool
 
 	Config Config
 
@@ -73,6 +74,7 @@ func (c *MountCommand) ParseFlags(ctx context.Context, args []string) (err error
 	fs := flag.NewFlagSet("litefs-mount", flag.ContinueOnError)
 	configPath := fs.String("config", "", "config file path")
 	noExpandEnv := fs.Bool("no-expand-env", false, "do not expand env vars in config")
+	noUnmount := fs.Bool("no-unmount", false, "do not unmount before mounting")
 	fuseDebug := fs.Bool("fuse.debug", false, "enable FUSE debug logging")
 	debug := fs.Bool("debug", false, "enable DEBUG level logging")
 	tracing := fs.Bool("tracing", false, "enable trace logging to stdout")
@@ -110,6 +112,8 @@ Arguments:
 		c.Config.Exec = ExecConfigSlice{{Cmd: strings.Join(args1, " ")}}
 	}
 
+	c.noUnmount = *noUnmount
+
 	// Override "debug" field if specified on the CLI.
 	if *fuseDebug {
 		c.Config.FUSE.Debug = true
@@ -489,7 +493,7 @@ func (c *MountCommand) initFileSystem(ctx context.Context) error {
 	fsys := fuse.NewFileSystem(c.Config.FUSE.Dir, c.Store)
 	fsys.AllowOther = c.Config.FUSE.AllowOther
 	fsys.Debug = c.Config.FUSE.Debug
-	if err := fsys.Mount(); err != nil {
+	if err := fsys.Mount(c.noUnmount); err != nil {
 		return fmt.Errorf("cannot open file system: %s", err)
 	}
 

fuse/file_system.go

@@ -58,9 +58,11 @@ func (fsys *FileSystem) Path() string { return fsys.path }
 func (fsys *FileSystem) Store() *litefs.Store { return fsys.store }
 
 // Mount mounts the file system to the mount point.
-func (fsys *FileSystem) Mount() (err error) {
-	// Attempt to unmount if it did not close cleanly before.
-	_ = fuse.Unmount(fsys.path)
+func (fsys *FileSystem) Mount(noUnmount bool) (err error) {
+	if !noUnmount {
+		// Attempt to unmount if it did not close cleanly before.
+		_ = fuse.Unmount(fsys.path)
+	}
 
 	// Ensure mount directory exists before trying to mount to it.
 	if err := os.MkdirAll(fsys.path, 0777); err != nil {

fuse/file_system_test.go

@@ -927,7 +927,7 @@ func newOpenFileSystem(tb testing.TB, path string, leaser *litefs.StaticLeaser)
 	tb.Helper()
 
 	fs := newFileSystem(tb, path, leaser)
-	if err := fs.Mount(); err != nil {
+	if err := fs.Mount(false); err != nil {
 		tb.Fatalf("cannot open file system: %s", err)
 	}