net: add renderers for automatically selecting the renderer.

Previously, the distro had hard coded which network renderer it would
use. This adds support for just picking the right renderer based
on what is available.

Now, that can be set via a priority in system_info, but should
generally work. That config looks like:
 system_info:
   network:
     renderers: ["eni", "sysconfig"]

When no renderers are found, a specific RendererNotFoundError is raised.
stages.py is modified to catch that and log it at error level. This
path should not really be exercised, but could occur if for example an
Ubuntu system did not have ifupdown, or a rhel system did not have
sysconfig. In such a system previously we would have quietly rendered
ENI configuration but that would have been ignored. This is one step
better in that we at least log the error.

1 files changed, 29 insertions, 14 deletions

diff --git a/cloudinit/util.py b/cloudinit/util.py
index 7196a7ca..82f2f76b 100644
--- a/cloudinit/util.py
+++ b/cloudinit/util.py
@@ -2099,21 +2099,36 @@ def get_mount_info(path, log=LOG):
         return parse_mount(path)
 
 
-def which(program):
-    # Return path of program for execution if found in path
-    def is_exe(fpath):
-        return os.path.isfile(fpath) and os.access(fpath, os.X_OK)
-
-    _fpath, _ = os.path.split(program)
-    if _fpath:
-        if is_exe(program):
+def is_exe(fpath):
+    # return boolean indicating if fpath exists and is executable.
+    return os.path.isfile(fpath) and os.access(fpath, os.X_OK)
+
+
+def which(program, search=None, target=None):
+    target = target_path(target)
+
+    if os.path.sep in program:
+        # if program had a '/' in it, then do not search PATH
+        # 'which' does consider cwd here. (cd / && which bin/ls) = bin/ls
+        # so effectively we set cwd to / (or target)
+        if is_exe(target_path(target, program)):
             return program
-    else:
-        for path in os.environ.get("PATH", "").split(os.pathsep):
-            path = path.strip('"')
-            exe_file = os.path.join(path, program)
-            if is_exe(exe_file):
-                return exe_file
+
+    if search is None:
+        paths = [p.strip('"') for p in
+                 os.environ.get("PATH", "").split(os.pathsep)]
+        if target == "/":
+            search = paths
+        else:
+            search = [p for p in paths if p.startswith("/")]
+
+    # normalize path input
+    search = [os.path.abspath(p) for p in search]
+
+    for path in search:
+        ppath = os.path.sep.join((path, program))
+        if is_exe(target_path(target, ppath)):
+            return ppath
 
     return None