fs_setup: if cmd is specified, use shell interpretation.

If 'cmd' is provided to a fs_setup entry, then cloud-init was trying
to execute the rendered string as a single name, rather than
splitting the string.  The change here will pass the string to
shell for interpretation so that it is split there.

Also fix some documentation errors and warn when fs_opts or overwrite
is provided along with 'cmd'.

LP: #1687712

1 files changed, 16 insertions, 5 deletions

diff --git a/cloudinit/config/cc_disk_setup.py b/cloudinit/config/cc_disk_setup.py
index f49386e3..6f827ddc 100644
--- a/cloudinit/config/cc_disk_setup.py
+++ b/cloudinit/config/cc_disk_setup.py
@@ -910,12 +910,23 @@ def mkfs(fs_cfg):
                         "must be set.", label)
 
     # Create the commands
+    shell = False
     if fs_cmd:
         fs_cmd = fs_cfg['cmd'] % {
             'label': label,
             'filesystem': fs_type,
             'device': device,
         }
+        shell = True
+
+        if overwrite:
+            LOG.warning(
+                "fs_setup:overwrite ignored because cmd was specified: %s",
+                fs_cmd)
+        if fs_opts:
+            LOG.warning(
+                "fs_setup:extra_opts ignored because cmd was specified: %s",
+                fs_cmd)
     else:
         # Find the mkfs command
         mkfs_cmd = util.which("mkfs.%s" % fs_type)
@@ -936,14 +947,14 @@ def mkfs(fs_cfg):
         if overwrite or device_type(device) == "disk":
             fs_cmd.append(lookup_force_flag(fs_type))
 
-    # Add the extends FS options
-    if fs_opts:
-        fs_cmd.extend(fs_opts)
+        # Add the extends FS options
+        if fs_opts:
+            fs_cmd.extend(fs_opts)
 
     LOG.debug("Creating file system %s on %s", label, device)
-    LOG.debug("     Using cmd: %s", " ".join(fs_cmd))
+    LOG.debug("     Using cmd: %s", str(fs_cmd))
     try:
-        util.subp(fs_cmd)
+        util.subp(fs_cmd, shell=shell)
     except Exception as e:
         raise Exception("Failed to exec of '%s':\n%s" % (fs_cmd, e))