saveconfig: compress the backup config files

We have noticed saveconfig.json with 100 storage objects and 100 targets
(each holding a single tpg and a portal) consumes disk space around ~500K.

Which is very expensive, and backing-up such 100 saveconfig.json files will
take ~50M of disk space under /etc/target/backup/

And at scale like 1000 storage objects and targets, this will become worst.

Hence this patch attempts to compress(gzip) and store saveconfig.json while
backing-up.

Saved space example:

[root@localhost ~]# targetcli ls | grep -e "user:glfs" -e "iscsi"
  | o- user:glfs ......................... [Storage Objects: 100]
  o- iscsi ............................... [Targets: 100]

[root@localhost ~]# du -sh /etc/target/saveconfig.json
448K    /etc/target/saveconfig.json

[root@localhost ~]# du -sh /etc/target/backup/saveconfig-20181128-18\:20\:43-json.gz
12K     /etc/target/backup/saveconfig-20181128-18:20:43-json.gz

Reducing disk usage per backup file from 448K to 12K is very efficient right.

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>

1 files changed, 39 insertions, 5 deletions

diff --git a/targetcli/ui_root.py b/targetcli/ui_root.py
index 38118bd..6f3a79b 100644
--- a/targetcli/ui_root.py
+++ b/targetcli/ui_root.py
@@ -24,6 +24,7 @@ import re
 import shutil
 import stat
 import filecmp
+import gzip
 
 from configshell_fb import ExecutionError
 from rtslib_fb import RTSRoot
@@ -62,6 +63,38 @@ class UIRoot(UINode):
             if fm.wwns == None or any(fm.wwns):
                 UIFabricModule(fm, self)
 
+    def _compare_files(self, backupfile, savefile):
+        '''
+        Compare backfile and saveconfig file
+        '''
+        if (os.path.splitext(backupfile)[1] == '.gz'):
+            try:
+                with gzip.open(backupfile, 'rb') as fbkp:
+                    fdata_bkp = fbkp.read()
+            except IOError as e:
+                self.shell.log.warning("Could not gzip open backupfile %s: %s"
+                                       % (backupfile, e.strerror))
+
+        else:
+            try:
+                with open(backupfile, 'rb') as fbkp:
+                    fdata_bkp = fbkp.read()
+            except IOError as e:
+                self.shell.log.warning("Could not open backupfile %s: %s"
+                                       % (backupfile, e.strerror))
+
+        try:
+            with open(savefile, 'rb') as f:
+                fdata = f.read()
+        except IOError as e:
+            self.shell.log.warning("Could not open saveconfig file %s: %s"
+                                   % (savefile, e.strerror))
+
+        if fdata_bkp == fdata:
+            return True
+        else:
+            return False
+
     def _save_backups(self, savefile):
         '''
         Take backup of config-file if needed.
@@ -72,7 +105,7 @@ class UIRoot(UINode):
 
         backup_dir = os.path.dirname(savefile) + "/backup/"
         backup_name = "saveconfig-" + \
-                      datetime.now().strftime("%Y%m%d-%H:%M:%S") + ".json"
+                      datetime.now().strftime("%Y%m%d-%H:%M:%S") + "-json.gz"
         backupfile = backup_dir + backup_name
         backup_error = None
 
@@ -88,13 +121,14 @@ class UIRoot(UINode):
             return
 
         backed_files_list = sorted(glob(os.path.dirname(savefile) + \
-                                   "/backup/*.json"))
+                                   "/backup/saveconfig-*json*"))
 
         # Save backup if backup dir is empty, or savefile is differnt from recent backup copy
-        if not backed_files_list or not filecmp.cmp(backed_files_list[-1], savefile):
+        if not backed_files_list or not self._compare_files(backed_files_list[-1], savefile):
             try:
-                shutil.copy(savefile, backupfile)
-
+                with open(savefile, 'rb') as f_in, gzip.open(backupfile, 'wb') as f_out:
+                    shutil.copyfileobj(f_in, f_out)
+                    f_out.flush()
             except IOError as ioe:
                 backup_error = ioe.strerror or "Unknown error"