rework package mirror selection

There are several changes here.
 * Datasource now has a 'availability_zone' getter.
 * get_package_mirror_info
   * Datasource convenience 'get_package_mirror_info' that calls
     the configured distro, and passes it the availability-zone
   * distro has a get_package_mirror_info method
   * get_package_mirror_info returns a dict that of name:mirror
     this is to facilitate use of 'security' and 'primary' archive.
   * this supports searching based on templates. Any template
     that references undefined values is skipped. These templates
     can contain 'availability_zone' (LP: #1037727)
   * distro's mirrors can be arch specific (LP: #1028501)
   * 'ec2_region' substitution variable is present only if this
     appears (by availability-zone naming convention) to be in EC2.
 * rename_apt_lists supports the "mirror_info" rather than single mirror
 * generate_sources_list supports mirror_info, and as a result, the
   ubuntu mirrors reference '$security' rather than security (LP: #1006963)
 * remove the DataSourceEc2 specific mirror selection, but instead
   rely on the above filtering, and the fact that 'ec2_region' is only
   defined if the availability_zone looks like a ec2 az.
 * package_mirrors is now required in the system_info config, a dict like:
   package_mirrors:
     - arches: [i386, amd64]
       failsafe:
         primary: http://archive.ubuntu.com/ubuntu
         security: http://security.ubuntu.com/ubuntu
       search:
         primary:
           - http://%(ec2_region)s.ec2.archive.ubuntu.com/ubuntu/
           - http://%(availability_zone)s.clouds.archive.ubuntu.com/ubuntu/
         security: []
     - arches: [armhf, armel, default]
       failsafe:
         primary: http://ports.ubuntu.com/ubuntu
         security: http://ports.ubuntu.com/ubuntu

LP: #1006963, #1028501, #1037727

1 files changed, 7 insertions, 3 deletions

diff --git a/cloudinit/sources/__init__.py b/cloudinit/sources/__init__.py
index ca9f58e5..4719d254 100644
--- a/cloudinit/sources/__init__.py
+++ b/cloudinit/sources/__init__.py
@@ -117,9 +117,9 @@ class DataSource(object):
     def get_locale(self):
         return 'en_US.UTF-8'
 
-    def get_local_mirror(self):
-        # ??
-        return None
+    @property
+    def availability_zone(self):
+        return self.metadata.get('availability-zone')
 
     def get_instance_id(self):
         if not self.metadata or 'instance-id' not in self.metadata:
@@ -166,6 +166,10 @@ class DataSource(object):
         else:
             return hostname
 
+    def get_package_mirror_info(self):
+        return self.distro.get_package_mirror_info(
+            availability_zone=self.availability_zone)
+
 
 def find_source(sys_cfg, distro, paths, ds_deps, cfg_list, pkg_list):
     ds_list = list_sources(cfg_list, ds_deps, pkg_list)