Add jsonschema for namespaced and verifiable module

configuration checking as well as make most of the
module logic happen in the module itself instead of
interacting with the distro object.

4 files changed, 107 insertions, 22 deletions

diff --git a/Requires b/Requires
index f19c9691..b00dd58e 100644
--- a/Requires
+++ b/Requires
@@ -34,3 +34,7 @@ boto
 
 # For patching pieces of cloud-config together
 jsonpatch
+
+# For validating that a config modules needed configuration specified
+# in a correct format that the module can understand
+jsonschema
diff --git a/cloudinit/config/cc_seed_random.py b/cloudinit/config/cc_seed_random.py
index 5d9890d5..acacb8f7 100644
--- a/cloudinit/config/cc_seed_random.py
+++ b/cloudinit/config/cc_seed_random.py
@@ -16,21 +16,91 @@
 #    You should have received a copy of the GNU General Public License
 #    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+import base64
+from StringIO import StringIO
+
+import jsonschema
+from jsonschema import exceptions as js_exc
+
+from cloudinit import exceptions as exc
 from cloudinit.settings import PER_INSTANCE
+from cloudinit import util
 
 frequency = PER_INSTANCE
+schema = {
+    'type': 'object',
+    'properties': {
+        "random_seed": {
+            "type": "object",
+            "oneOf": [
+                {"$ref": "#/definitions/random_seed"},
+            ],
+        },
+    },
+    "required": ["random_seed"],
+    "additionalProperties": True,
+    "definitions": {
+        'random_seed': {
+            'type': 'object',
+            "properties" : {
+                'data': {
+                    'type': "string",
+                },
+                'file': {
+                    'type': 'string',
+                },
+                'encoding': {
+                    "enum": ["base64", 'gzip', 'b64', 'gz', ''],
+                },
+            },
+            "additionalProperties": True,
+        },
+    },
+}
+
+
+def validate(cfg):
+    """Method that can be used to ask if the given configuration will be
+    accepted as valid by this module, without having to actually activate this
+    module."""
+    try:
+        jsonschema.validate(cfg, schema)
+    except js_exc.ValidationError as e:
+        raise exc.FormatValidationError("Invalid configuration: %s" % str(e))
+
+
+def _decode(data, encoding=None):
+    if not encoding:
+        return data
+    if not data:
+        return ''
+    if encoding.lower() in ['base64', 'b64']:
+        return base64.b64decode(data)
+    elif encoding.lower() in ['gzip', 'gz']:
+        return util.decomp_gzip(data, quiet=False)
+    else:
+        raise IOError("Unknown random_seed encoding: %s" % (encoding))
 
 
 def handle(name, cfg, cloud, log, _args):
-    random_seed = None
-    # Prefer metadata over cfg for random_seed
-    for src in (cloud.datasource.metadata, cfg):
-        if not src:
-            continue
-        tmp_random_seed = src.get('random_seed')
-        if tmp_random_seed and isinstance(tmp_random_seed, (str, basestring)):
-            random_seed = tmp_random_seed
-            break
-    if random_seed:
-        log.debug("%s: setting random seed", name)
-        cloud.distro.set_random_seed(random_seed)
+    if not cfg or "random_seed" not in cfg:
+        log.debug(("Skipping module named %s, "
+                   "no 'random_seed' configuration found"), name)
+        return
+
+    validate(cfg)
+    my_cfg = cfg['random_seed']
+    seed_path = my_cfg.get('file', '/dev/urandom')
+    seed_buf = StringIO()
+    seed_buf.write(_decode(my_cfg.get('data', ''),
+                           encoding=my_cfg.get('encoding')))
+
+    metadata = cloud.datasource.metadata
+    if metadata and 'random_seed' in metadata:
+        seed_buf.write(metadata['random_seed'])
+
+    seed_data = seed_buf.getvalue()
+    if len(seed_data):
+        log.debug("%s: adding %s bytes of random seed entrophy to %s", name,
+                  len(seed_data), seed_path)
+        util.append_file(seed_path, seed_data)
diff --git a/cloudinit/distros/__init__.py b/cloudinit/distros/__init__.py
index 5642b529..74e95797 100644
--- a/cloudinit/distros/__init__.py
+++ b/cloudinit/distros/__init__.py
@@ -52,7 +52,6 @@ class Distro(object):
     ci_sudoers_fn = "/etc/sudoers.d/90-cloud-init-users"
     hostname_conf_fn = "/etc/hostname"
     tz_zone_dir = "/usr/share/zoneinfo"
-    random_seed_fn = '/dev/urandom'
 
     def __init__(self, name, cfg, paths):
         self._paths = paths
@@ -170,15 +169,6 @@ class Distro(object):
             distros.extend(OSFAMILIES[family])
         return distros
 
-    def set_random_seed(self, seed):
-        if not self.random_seed_fn or not os.path.exists(self.random_seed_fn):
-            raise IOError("No random seed filename provided for %s"
-                          % (self.name))
-        if not seed:
-            raise IOError("Unable to set empty random seed")
-        # Ensure we only write 512 bytes worth
-        util.append_file(self.random_seed_fn, seed[0:512])
-
     def update_hostname(self, hostname, fqdn, prev_hostname_fn):
         applying_hostname = hostname
 
diff --git a/cloudinit/exceptions.py b/cloudinit/exceptions.py
new file mode 100644
index 00000000..c09d15b1
--- /dev/null
+++ b/cloudinit/exceptions.py
@@ -0,0 +1,21 @@
+# vi: ts=4 expandtab
+#
+#    Copyright (C) 2013 Yahoo! Inc.
+#
+#    Author: Joshua Harlow <harlowja@yahoo-inc.com>
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License version 3, as
+#    published by the Free Software Foundation.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+class FormatValidationError(Exception):
+    pass