Merge lp:~ltrager/maas-images/import_all_centos_images into lp:maas-images

[Lee Trager]

Download CentOS images with a short version string

http://cloud.centos.org/centos/ now contains images using a shorter version string in the format of YYMM. We know the second format is referencing the year and month by looking at the timestamp of each image. To ensure MAAS chooses the correct version expand the short version into a long version.

Upstream is producing new CentOS images with a short version string. Previously the format YYYYMMDD_XX was used, now they are using YYMM. This modifies CentOS import to capture all images and converts the short version string into a long version string so MAAS uses the latest image, not the one with the longest version string.

[Scott Moser (smoser)]

ok. please fix with:
a.) clean up the inline comments as to where the YYMM (4 digit string) comes from
b.) improve the commit message to be
    summary
    blank line
    nice description like in your 'description of change' please describe also where YYMM comes from

[lp:~ltrager/maas-images/import_all_centos_images]

292. By Lee Trager on 2016-04-18

Merge centos-python23

293. By Lee Trager on 2016-04-18

Add better comment

=== modified file 'meph2/commands/meph2_util.py'
--- meph2/commands/meph2_util.py	2016-01-25 18:35:31 +0000
+++ meph2/commands/meph2_util.py	2016-04-18 22:40:32 +0000
@@ -332,7 +332,12 @@
     """
     ret = dict()
     content = geturl_text(url)
-    prog = re.compile('[0-9]{8}(_[0-9]+)')
+    # http://cloud.centos.org/centos/ contains images using two version
+    # strings. The first is only used on older images and uses the format
+    # YYYYMMDD_XX. The second is used on images generated monthly using the
+    # format YYMM. We know the second format is referencing the year and month
+    # by looking at the timestamp of each image.
+    prog = re.compile('([\d]{8}(_[\d]+))|(\d{4})')
 
     for i in content.split('\n'):
         try:
@@ -347,6 +352,11 @@
             continue
         img_version = m.group(0)
 
+        # Turn the short version string into a long version string so that MAAS
+        # uses the latest version, not the longest
+        if len(img_version) == 4:
+            img_version = "20%s01_01" % img_version
+
         # Prefer compressed image over uncompressed
         if (img_version in ret and
                 ret[img_version]['img_name'].endswith('qcow2.xz')):