Do not require useless metadata

url would be more useful than file+urlmd5
(slapos.buildout will be changed this way)

However, prevent the user from passing empty metadata inadvertently.
Of course, that won't reject dummy information but it's unlikely there's
nothing useful to add.

slapos/libnetworkcache.py

@@ -330,8 +330,7 @@ class NetworkcacheClient(object):
     finally:
       f is None or f.close()
 
-  def upload(self, file_descriptor, key=None, urlmd5=None, file_name=None,
-                                    valid_until=None, architecture=None, **kw):
+  def upload(self, file_descriptor, key=None, **kw):
     ''' Upload the file to the server.
     If key is None it must only upload to SHACACHE.
     Otherwise, it must create a new entry on SHADIR.
@@ -374,16 +373,9 @@ class NetworkcacheClient(object):
       f is None or f.close()
 
     if key is not None:
-      kw['sha512'] = sha512sum # always update sha512sum
-      file_name = kw.pop('file', file_name)
-      if file_name is None or urlmd5 is None:
-        raise NetworkcacheException(
-          'file_name and urlmd5 are required for non-generic upload')
-      if valid_until is not None:
-        kw['valid-until'] = valid_until
-      if architecture is not None:
-        kw['architecture'] = architecture
-      self.index(key, file=file_name, urlmd5=urlmd5, **kw)
+      if not kw:
+          raise NetworkcacheException('metadata should not be empty')
+      self.index(key, sha512=sha512sum, **kw)
 
     return sha512sum
 
@@ -504,15 +496,13 @@ def cmd_upload(*args):
         nc.upload(f)
         return
     elif args.url:
-      parser.error('either --file or --url is required')
-    elif os.path.isdir(args.url):
-      f = nc.archive(args.url)
+      f = (nc.archive if os.path.isdir(args.url) else urlopen)(args.url)
     else:
-      f = urlopen(args.url)
+      parser.error('either --file or --url is required')
+    kw = dict(x.split('=', 1) for x in args.meta)
+    kw.setdefault('url', args.url)
     urlmd5 = hashlib.md5(args.url.encode()).hexdigest()
-    nc.upload(f, args.prefix_key + urlmd5 + args.suffix_key, urlmd5=urlmd5,
-              file_name=os.path.basename(args.url) or "file",
-              **dict(x.split('=', 1) for x in args.meta))
+    nc.upload(f, args.prefix_key + urlmd5 + args.suffix_key, **kw)
   finally:
     f is None or f.close()