AllocDirBuilder that creates the alloc directory structure

client/allocdir/alloc_dir_linux.go

@@ -0,0 +1,98 @@
+// +build !windows
+
+package allocdir
+
+import (
+	"fmt"
+	"github.com/hashicorp/nomad/nomad/structs"
+	"os"
+	"os/user"
+	"path/filepath"
+	"strconv"
+)
+
+func (d *AllocDir) Build(tasks []*structs.Task) error {
+	// Make the alloc directory, owned by the nomad process.
+	if err := os.Mkdir(d.AllocDir, 0700); err != nil {
+		return fmt.Errorf("Failed to make the alloc directory %v: %v", d.AllocDir, err)
+	}
+
+	nobody, err := user.Lookup("nobody")
+	if err != nil {
+		return fmt.Errorf("Could not set owner/group on shared alloc directory: %v", err)
+	}
+
+	uid, err := getUid(nobody)
+	if err != nil {
+		return err
+	}
+
+	gid, err := getGid(nobody)
+	if err != nil {
+		return err
+	}
+
+	// Make the shared directory and make it availabe to all user/groups.
+	if err := mkOwnedDir(d.SharedDir, uid, gid, 0777); err != nil {
+		return err
+	}
+
+	for _, dir := range SharedAllocDirs {
+		p := filepath.Join(d.SharedDir, dir)
+		if err := mkOwnedDir(p, uid, gid, 0777); err != nil {
+			return err
+		}
+	}
+
+	// Make the task directories.
+	for _, t := range tasks {
+		p := filepath.Join(d.AllocDir, t.Name)
+		if err := mkOwnedDir(p, uid, gid, 0777); err != nil {
+			return err
+		}
+
+		// Create a local directory that each task can use.
+		local := filepath.Join(p, TaskLocal)
+		if err := mkOwnedDir(local, uid, gid, 0777); err != nil {
+			return err
+		}
+		d.TaskDirs[t.Name] = local
+
+		// TODO: Mount the shared alloc dir into each task dir.
+	}
+
+	return nil
+}
+
+// mkOwnedDir creates the directory specified by the path with the passed
+// permissions. It also sets the passed uid and gid. It returns an error if any
+// of these operations fail.
+func mkOwnedDir(path string, uid, gid int, perm os.FileMode) error {
+	if err := os.Mkdir(path, perm); err != nil {
+		return fmt.Errorf("Failed to make directory %v: %v", path, err)
+	}
+
+	if err := os.Chown(path, uid, gid); err != nil {
+		return fmt.Errorf("Couldn't change owner/group of %v to (uid: %v, gid: %v): %v", path, uid, gid, err)
+	}
+
+	return nil
+}
+
+func getUid(u *user.User) (int, error) {
+	uid, err := strconv.Atoi(u.Uid)
+	if err != nil {
+		return 0, fmt.Errorf("Unable to convert Uid to an int: %v", err)
+	}
+
+	return uid, nil
+}
+
+func getGid(u *user.User) (int, error) {
+	gid, err := strconv.Atoi(u.Gid)
+	if err != nil {
+		return 0, fmt.Errorf("Unable to convert Gid to an int: %v", err)
+	}
+
+	return gid, nil
+}