Move subp into its own module. (#416)

This was painful, but it finishes a TODO from cloudinit/subp.py.

It moves the following from util to subp:
  ProcessExecutionError
  subp
  which
  target_path

I moved subp_blob_in_tempfile into cc_chef, which is its only caller.
That saved us from having to deal with it using write_file
and temp_utils from subp (which does not import any cloudinit things now).

It is arguable that 'target_path' could be moved to a 'path_utils' or
something, but in order to use it from subp and also from utils,
we had to get it out of utils.

1 files changed, 3 insertions, 2 deletions

diff --git a/cloudinit/config/cc_seed_random.py b/cloudinit/config/cc_seed_random.py
index b65f3ed9..4fb9b44e 100644
--- a/cloudinit/config/cc_seed_random.py
+++ b/cloudinit/config/cc_seed_random.py
@@ -65,6 +65,7 @@ from io import BytesIO
 
 from cloudinit import log as logging
 from cloudinit.settings import PER_INSTANCE
+from cloudinit import subp
 from cloudinit import util
 
 frequency = PER_INSTANCE
@@ -92,14 +93,14 @@ def handle_random_seed_command(command, required, env=None):
         return
 
     cmd = command[0]
-    if not util.which(cmd):
+    if not subp.which(cmd):
         if required:
             raise ValueError(
                 "command '{cmd}' not found but required=true".format(cmd=cmd))
         else:
             LOG.debug("command '%s' not found for seed_command", cmd)
             return
-    util.subp(command, env=env, capture=False)
+    subp.subp(command, env=env, capture=False)
 
 
 def handle(name, cfg, cloud, log, _args):