Add ability to run the provisioner directly on the ZFS host.

The default is to run kubernetes-zfs-provisioner in a container and
create datasets via SSH on a remote host.
To do that, the docker image is created with the zfs and
update-permissions stubs that will both call commands on the remote host
using SSH.

Allows running kubernetes-zfs-provisioner directly on the ZFS host by
making the update-permissions script presence optional. The zfs stub is
already optional because it merely replaces the command of the same name
on the remote host. The provisionner now uses the update-permissions
executable if it's present in the current PATH, otherwise it falls back
to executing chmod g+w directly.

Fixes #130.

docker/update-permissions.sh

@@ -5,7 +5,9 @@ set -eo pipefail
 zfs_mod="${ZFS_MOD:-g+w}"
 chmod_bin=${ZFS_CHOWN_BIN:-sudo -H chmod}
 
-zfs_host="${1}"
-zfs_mountpoint="${2}"
+zfs_mountpoint="${1}"
+
+# Do not try to manually modify these Env vars, they will be updated by the provisioner just before invoking the script.
+zfs_host="${ZFS_HOST}"
 
 ssh "${zfs_host}" "${chmod_bin} ${zfs_mod} ${zfs_mountpoint}"

pkg/zfs/zfs.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
+	"path/filepath"
 	"sync"
 
 	gozfs "github.com/mistifyio/go-zfs/v3"
@@ -114,7 +115,18 @@ func (z *zfsImpl) SetPermissions(dataset *Dataset) error {
 	if dataset.Mountpoint == "" {
 		return fmt.Errorf("undefined mountpoint for dataset: %s", dataset.Name)
 	}
-	cmd := exec.Command("update-permissions", dataset.Hostname, dataset.Mountpoint)
+
+	globalLock.Lock()
+	defer globalLock.Unlock()
+	if err := setEnvironmentVars(dataset.Hostname); err != nil {
+		return err
+	}
+	cmd := exec.Command("update-permissions", dataset.Mountpoint)
+	if !filepath.IsAbs(cmd.Path) {
+		// update-permissions not found in PATH
+		cmd = exec.Command("chmod", "g+w", dataset.Mountpoint)
+	}
+
 	out, err := cmd.CombinedOutput()
 	if err != nil {
 		return fmt.Errorf("could not update permissions on '%s': %w: %s", dataset.Hostname, err, out)

test/update-permissions

@@ -5,6 +5,6 @@ set -eo pipefail
 zfs_mod="${ZFS_MOD:-g+w}"
 chmod_bin=${ZFS_CHOWN_BIN:-chmod}
 
-zfs_mountpoint="${2}"
+zfs_mountpoint="${1}"
 
 ${chmod_bin} ${zfs_mod} ${zfs_mountpoint}