Use dedicated section for networkcache.

If it is possible to use slapos.libnetworkcache check if parameter
networkcache-section exists. If so, try to find section named by this parameter.

Such section has two required parameters: download-cache-url and
download-dir-url. upload-cache-url and upload-dir-url are optional parameters.

Minimalistic profile for networkcache control looks like:

  [buildout]
  parts =

  networkcache-section = readcache

  [readcache]
  download-cache-url = http:///
  download-dir-url = http:///
  #upload-cache-url = http:///
  #upload-dir-url = http:///

src/zc/buildout/buildout.py

@@ -336,6 +336,32 @@ class Buildout(UserDict.DictMixin):
 
         os.chdir(options['directory'])
 
+        if LIBNETWORKCACHE_ENABLED:
+            # support networkcache
+            networkcache_section_name = options.get('networkcache-section')
+            if networkcache_section_name:
+                networkcache_section = self[networkcache_section_name]
+                self.download_cache_url = networkcache_section[
+                    'download-cache-url']
+                self.download_dir_url = networkcache_section[
+                    'download-dir-url']
+                self.upload_cache_url = networkcache_section.get(
+                    'upload-cache-url', '')
+                self.upload_dir_url = networkcache_section.get(
+                    'upload-dir-url', '')
+                self._logger.info('Networkcache enabled.')
+                self._logger.info('Networkcache download cache: %r, directory '
+                    '%r' % (self.download_cache_url, self.download_dir_url))
+                self._logger.info('Networkcache upload cache: %r, directory %r'%
+                    (self.upload_cache_url, self.upload_dir_url))
+            else:
+                self._logger.warning('Networkcache functionality not enabled.')
+                self.download_cache_url = None
+                self.download_dir_url = None
+                self.upload_cache_url = None
+                self.upload_dir_url = None
+
+
     def _buildout_path(self, name):
         if '${' in name:
             return name
@@ -370,8 +396,8 @@ class Buildout(UserDict.DictMixin):
                 newest=self.newest,
                 allow_hosts=self._allow_hosts,
                 prefer_final=not self.accept_buildout_test_releases,
-                sha_cache=options.get('sha-cache'),
-                sha_dir=options.get('sha-dir'),
+                sha_cache=self.download_cache_url,
+                sha_dir=self.download_dir_url,
                 )
 
         # Now copy buildout and setuptools eggs, and record destination eggs:
@@ -873,8 +899,8 @@ class Buildout(UserDict.DictMixin):
             path = [options['develop-eggs-directory']],
             allow_hosts = self._allow_hosts,
             prefer_final=not self.accept_buildout_test_releases,
-            sha_cache=options.get('sha-cache'),
-            sha_dir=options.get('sha-cache'),
+            sha_cache=self.download_cache_url,
+            sha_dir=self.download_dir_url,
             )
 
         upgraded = []
@@ -1103,8 +1129,8 @@ def _install_and_load(spec, group, entry, buildout):
                 newest=buildout.newest,
                 allow_hosts=buildout._allow_hosts,
                 prefer_final=not buildout.accept_buildout_test_releases,
-                sha_dir=buildout_options.get('sha-dir'),
-                sha_cache=buildout_options.get('sha-cache'))
+                sha_cache=self.download_cache_url,
+                sha_dir=self.download_dir_url)
 
         __doing__ = 'Loading %s recipe entry %s:%s.', group, spec, entry
         return pkg_resources.load_entry_point(