replace 'cloudconfig' entries in fstab rather than appending (LP: #524562)

This marks the comment option of fs_mntops in fstab (man fstab) with
cloudconfig for each of the mount options added by cloudconfig.  It will
search through existing lines, any entry written by cloudconfig will
be deleted.

LP: #524562

1 files changed, 24 insertions, 4 deletions

diff --git a/cloudinit/CloudConfig.py b/cloudinit/CloudConfig.py
index 9eb2d00b..487e9872 100644
--- a/cloudinit/CloudConfig.py
+++ b/cloudinit/CloudConfig.py
@@ -26,6 +26,8 @@ import os
 import glob
 import sys
 import time
+import re
+import string
 
 per_instance="once-per-instance"
 cronpre = "/etc/cron.d/cloudinit"
@@ -344,15 +346,33 @@ class CloudConfig():
     
         if len(actlist) == 0: return
     
+        comment="comment=cloudconfig"
+        cc_lines = [ ]
         needswap = False
         dirs = [ ]
-
-        fstab=file("/etc/fstab","ab")
-        fstab.write("# cloud-config mounts\n")
         for line in actlist:
-            fstab.write('\t'.join(line) + "\n")
+            # write 'comment' in the fs_mntops, entry,  claiming this
+            line[3]="%s,comment=cloudconfig" % line[3]
             if line[2] == "swap": needswap = True
             if line[1].startswith("/"): dirs.append(line[1])
+            cc_lines.append('\t'.join(line))
+
+        fstab_lines = [ ]
+        fstab=open("/etc/fstab","r+")
+        ws = re.compile("[%s]+" % string.whitespace)
+        for line in fstab.read().splitlines():
+            try:
+                toks = ws.split(line)
+                if toks[3].find(comment) != -1: continue
+            except:
+                pass
+            fstab_lines.append(line)
+
+        fstab_lines.extend(cc_lines)
+            
+        fstab.seek(0)
+        fstab.write("%s\n" % '\n'.join(fstab_lines))
+        fstab.truncate()
         fstab.close()
     
         if needswap: