support $MIRROR and $RELEASE in apt-source cloud-config lines (LP: #693292)

sources can use $MIRROR and $RELEASE and they will be replaced
with the local mirror for this cloud, and the running release
this:
 - source: deb $MIRROR $RELEASE multiverse
would possibly be turned into:
 - source: deb http://us-east-1.ec2.archive.ubuntu.com/ubuntu natty multiverse

LP: #693292

3 files changed, 25 insertions, 9 deletions

diff --git a/cloudinit/CloudConfig/cc_apt_update_upgrade.py b/cloudinit/CloudConfig/cc_apt_update_upgrade.py
index 396c5e09..e918e8c8 100644
--- a/cloudinit/CloudConfig/cc_apt_update_upgrade.py
+++ b/cloudinit/CloudConfig/cc_apt_update_upgrade.py
@@ -25,20 +25,23 @@ def handle(name,cfg,cloud,log,args):
     update = util.get_cfg_option_bool(cfg, 'apt_update', False)
     upgrade = util.get_cfg_option_bool(cfg, 'apt_upgrade', False)
 
+    release = get_release()
+    if cfg.has_key("apt_mirror"):
+        mirror = cfg["apt_mirror"]
+    else:
+        mirror = cloud.get_mirror()
+
     if not util.get_cfg_option_bool(cfg, \
         'apt_preserve_sources_list', False):
-        if cfg.has_key("apt_mirror"):
-            mirror = cfg["apt_mirror"]
-        else:
-            mirror = cloud.get_mirror()
-        generate_sources_list(mirror)
+        generate_sources_list(release, mirror)
         old_mir = util.get_cfg_option_str(cfg,'apt_old_mirror', \
             "archive.ubuntu.com/ubuntu")
         rename_apt_lists(old_mir, mirror)
 
     # process 'apt_sources'
     if cfg.has_key('apt_sources'):
-        errors = add_sources(cfg['apt_sources'])
+        errors = add_sources(cfg['apt_sources'],
+                             { 'MIRROR' : mirror, 'RELEASE' : release } )
         for e in errors:
             log.warn("Source Error: %s\n" % ':'.join(e))
 
@@ -96,17 +99,18 @@ def rename_apt_lists(omirror,new_mirror,lists_d="/var/lib/apt/lists"):
     for file in glob.glob("%s_*" % oprefix):
         os.rename(file,"%s%s" % (nprefix, file[olen:]))
 
-def generate_sources_list(mirror):
+def get_release():
     stdout, stderr = subprocess.Popen(['lsb_release', '-cs'], stdout=subprocess.PIPE).communicate()
-    codename = stdout.strip()
+    return(stdout.strip())
 
+def generate_sources_list(codename, mirror):
     util.render_to_file('sources.list', '/etc/apt/sources.list', \
         { 'mirror' : mirror, 'codename' : codename })
 
 # srclist is a list of dictionaries, 
 # each entry must have: 'source'
 # may have: key, ( keyid and keyserver)
-def add_sources(srclist):
+def add_sources(srclist, searchList={ }):
     elst = []
 
     for ent in srclist:
@@ -121,6 +125,8 @@ def add_sources(srclist):
                 elst.append([source, "add-apt-repository failed"])
             continue
 
+        source = util.render_string(source, searchList)
+
         if not ent.has_key('filename'):
             ent['filename']='cloud_config_sources.list'
 
diff --git a/cloudinit/util.py b/cloudinit/util.py
index 7c9e60d5..d5ae2bec 100644
--- a/cloudinit/util.py
+++ b/cloudinit/util.py
@@ -136,6 +136,10 @@ def render_to_file(template, outfile, searchList):
     f.write(t.respond())
     f.close()
 
+def render_string(template, searchList):
+    return(Template(template, searchList=[searchList]).respond())
+
+
 # read_optional_seed
 # returns boolean indicating success or failure (presense of files)
 # if files are present, populates 'fill' dictionary with 'user-data' and
diff --git a/doc/examples/cloud-config.txt b/doc/examples/cloud-config.txt
index 58082667..a32fd038 100644
--- a/doc/examples/cloud-config.txt
+++ b/doc/examples/cloud-config.txt
@@ -48,6 +48,12 @@ apt_sources:
  #    See sources.list man page for more information about the format
  - source: deb http://archive.ubuntu.com/ubuntu karmic-backports main universe multiverse restricted
 
+ # sources can use $MIRROR and $RELEASE and they will be replaced
+ # with the local mirror for this cloud, and the running release
+ # the entry below would be possibly turned into:
+ # - source: deb http://us-east-1.ec2.archive.ubuntu.com/ubuntu natty multiverse
+ - source: deb $MIRROR $RELEASE multiverse
+
  # this would have the same end effect as 'ppa:byobu/ppa'
  - source: "deb http://ppa.launchpad.net/byobu/ppa/ubuntu karmic main"
    keyid: F430BBA5 # GPG key ID published on a key server