Allow a url to cloud-config data to be specified on kernel config line

In order to allow an ephemeral, or otherwise pristine image to
receive some configuration, cloud-init will read a url directed by
the kernel command line and proceed as if its data had previously existed.

For more information, see doc/kernel-cmdline.txt

1 files changed, 26 insertions, 0 deletions

diff --git a/cloudinit/__init__.py b/cloudinit/__init__.py
index 6d276d84..85c6fd1b 100644
--- a/cloudinit/__init__.py
+++ b/cloudinit/__init__.py
@@ -137,7 +137,9 @@ class CloudInit:
 
         if ds_deps != None:
             self.ds_deps = ds_deps
+
         self.sysconfig = sysconfig
+
         self.cfg = self.read_cfg()
 
     def read_cfg(self):
@@ -639,3 +641,27 @@ class InternalPartHandler:
 
     def handle_part(self, data, ctype, filename, payload, frequency):
         return(self.handler(data, ctype, filename, payload, frequency))
+
+
+def get_cmdline_url(names=('cloud-config-url', 'url'),
+                    starts="#cloud-config", cmdline=None):
+
+    if cmdline == None:
+        cmdline = util.get_cmdline()
+
+    data = util.keyval_str_to_dict(cmdline)
+    url = None
+    key = None
+    for key in names:
+        if key in data:
+            url = data[key]
+            break
+    if url == None:
+        return (None, None, None)
+
+    contents = util.readurl(url)
+
+    if contents.startswith(starts):
+        return (key, url, contents)
+
+    return (key, url, None)