Hetzner: support reading user-data that is base64 encoded. (#448)

Hetzner cloud only supports user-data as a string (presumably utf-8).

In order to allow users on Hetzner to provide binary data to cloud-init,
we will attempt to base64decode the userdata.

The change here adds a 'maybe_b64decode' function that will decode data
if and only if is base64 encoded.

The reason for not using util.b64d is that we do not want the return value
decoded to a string, and util.b64d will do that if it can.  Additionally
we call decode with validate=True which oddly is not the default.

LP: #1884071

1 files changed, 8 insertions, 1 deletions

diff --git a/cloudinit/sources/DataSourceHetzner.py b/cloudinit/sources/DataSourceHetzner.py
index 50298330..70e4274c 100644
--- a/cloudinit/sources/DataSourceHetzner.py
+++ b/cloudinit/sources/DataSourceHetzner.py
@@ -59,7 +59,14 @@ class DataSourceHetzner(sources.DataSource):
                 self.userdata_address, timeout=self.timeout,
                 sec_between=self.wait_retry, retries=self.retries)
 
-        self.userdata_raw = ud
+        # Hetzner cloud does not support binary user-data. So here, do a
+        # base64 decode of the data if we can. The end result being that a
+        # user can provide base64 encoded (possibly gzipped) data as user-data.
+        #
+        # The fallout is that in the event of b64 encoded user-data,
+        # /var/lib/cloud-init/cloud-config.txt will not be identical to the
+        # user-data provided.  It will be decoded.
+        self.userdata_raw = hc_helper.maybe_b64decode(ud)
         self.metadata_full = md
 
         """hostname is name provided by user at launch.  The API enforces