read_file_or_url: raise UrlError with 404 on ENOENT

This makes it easier to call read_file_or_url and handle file or url
errors.  Now read_file_or_url will raise a UrlError in either case
on errors.

cloudinit/url_helper.py

@@ -20,6 +20,7 @@
 #    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 httplib
 import time
 
 import requests
@@ -32,6 +33,8 @@ from cloudinit import version
 
 LOG = logging.getLogger(__name__)
 
+NOT_FOUND = httplib.NOT_FOUND
+
 # Check if requests has ssl support (added in requests >= 0.8.8)
 SSL_ENABLED = False
 CONFIG_ENABLED = False  # This was added in 0.7 (but taken out in >=1.0)
@@ -58,6 +61,31 @@ def _cleanurl(url):
     return urlunparse(parsed_url)
 
 
+# Made to have same accessors as UrlResponse so that the
+# read_file_or_url can return this or that object and the
+# 'user' of those objects will not need to know the difference.
+class StringResponse(object):
+    def __init__(self, contents, code=200):
+        self.code = code
+        self.headers = {}
+        self.contents = contents
+        self.url = None
+
+    def ok(self, *args, **kwargs):  # pylint: disable=W0613
+        if self.code != 200:
+            return False
+        return True
+
+    def __str__(self):
+        return self.contents
+
+
+class FileResponse(StringResponse):
+    def __init__(self, path, contents, code=200):
+        StringResponse.__init__(self, contents, code=code)
+        self.url = path
+
+
 class UrlResponse(object):
     def __init__(self, response):
         self._response = response

cloudinit/util.py

@@ -74,31 +74,6 @@ FN_ALLOWED = ('_-.()' + string.digits + string.ascii_letters)
 CONTAINER_TESTS = ['running-in-container', 'lxc-is-container']
 
 
-# Made to have same accessors as UrlResponse so that the
-# read_file_or_url can return this or that object and the
-# 'user' of those objects will not need to know the difference.
-class StringResponse(object):
-    def __init__(self, contents, code=200):
-        self.code = code
-        self.headers = {}
-        self.contents = contents
-        self.url = None
-
-    def ok(self, *args, **kwargs):  # pylint: disable=W0613
-        if self.code != 200:
-            return False
-        return True
-
-    def __str__(self):
-        return self.contents
-
-
-class FileResponse(StringResponse):
-    def __init__(self, path, contents, code=200):
-        StringResponse.__init__(self, contents, code=code)
-        self.url = path
-
-
 class ProcessExecutionError(IOError):
 
     MESSAGE_TMPL = ('%(description)s\n'
@@ -651,8 +626,8 @@ def read_optional_seed(fill, base="", ext="", timeout=5):
         fill['user-data'] = ud
         fill['meta-data'] = md
         return True
-    except IOError as e:
+    except url_helper.UrlError as e:
-        if e.errno == errno.ENOENT:
+        if e.code == url_helper.NOT_FOUND:
             return False
         raise
 
@@ -699,7 +674,14 @@ def read_file_or_url(url, timeout=5, retries=10,
         if data:
             LOG.warn("Unable to post data to file resource %s", url)
         file_path = url[len("file://"):]
-        return FileResponse(file_path, contents=load_file(file_path))
+        try:
+            contents = load_file(file_path)
+        except IOError as e:
+            code = e.errno
+            if e.errno == errno.ENOENT:
+                code = url_helper.NOT_FOUND
+            raise url_helper.UrlError(cause=e, code=code, headers=None)
+        return url_helper.FileResponse(file_path, contents=contents)
     else:
         return url_helper.readurl(url,
                                   timeout=timeout,

tests/unittests/test__init__.py

@@ -196,7 +196,7 @@ class TestCmdlineUrl(MockerTestCase):
         mock_readurl = self.mocker.replace(url_helper.readurl,
                                            passthrough=False)
         mock_readurl(url, ARGS, KWARGS)
-        self.mocker.result(util.StringResponse(payload))
+        self.mocker.result(url_helper.StringResponse(payload))
         self.mocker.replay()
 
         self.assertEqual((key, url, None),
@@ -212,7 +212,7 @@ class TestCmdlineUrl(MockerTestCase):
         mock_readurl = self.mocker.replace(url_helper.readurl,
                                            passthrough=False)
         mock_readurl(url, ARGS, KWARGS)
-        self.mocker.result(util.StringResponse(payload))
+        self.mocker.result(url_helper.StringResponse(payload))
         self.mocker.replay()
 
         self.assertEqual((key, url, payload),
@@ -225,7 +225,7 @@ class TestCmdlineUrl(MockerTestCase):
         cmdline = "ro %s=%s bar=1" % (key, url)
 
         self.mocker.replace(url_helper.readurl, passthrough=False)
-        self.mocker.result(util.StringResponse(""))
+        self.mocker.result(url_helper.StringResponse(""))
         self.mocker.replay()
 
         self.assertEqual((None, None, None),

tests/unittests/test_datasource/test_maas.py

@@ -122,7 +122,7 @@ class TestMAASDataSource(mocker.MockerTestCase):
                          headers_cb=my_headers_cb,
                          exception_cb=mocker.ANY)
             resp = valid.get(key)
-            self.mocker.result(util.StringResponse(resp))
+            self.mocker.result(url_helper.StringResponse(resp))
         self.mocker.replay()
 
         (userdata, metadata) = DataSourceMAAS.read_maas_seed_url(my_seed,