Add prefix-ed borg prune command

Also adjust archive naming to make for easy prefix-ing

Author: HubbeKing

README.md

@@ -16,7 +16,7 @@ This repo will soon contain a docker image and kubernetes resource YAMLs for bac
   - Uses this dictionary to save backups using the PVC name rather than the volume name
     - The PVC name is typically specified by the user in a PVC resource YAML
     - The volume name may be automatically generated by a dynamic volume provisioner
-    - Goal is to have archives in borg repo named something like `2020-03-01-sonarr` rather than `2020-03-01-pvc-b1397318-8fa4-4216-aa6b-6568d1394e89`
+    - Goal is to have archives in borg repo named something like `sonarr-2020-03-01` rather than `pvc-b1397318-8fa4-4216-aa6b-6568d1394e89-2020-03-01`
     - Archive contents will be a 1:1 reproduction of the PVC storage contents at time of archive creation
 - TBD:
   - Generic script to restore a borg backup to a k8s volume

k8s-volume-backup.py

@@ -37,11 +37,17 @@
     # get the pvc metadata name using the parsed get pvc output
     pvc_name = pvc_data.get(volume_name, "")
     if pvc_name:
-        # create a borg archive named according to YYYY-MM-DD-pvc.metadata.name, cd-ing into the volume directory first
+        # create a borg archive named according to pvc.metadata.name-YYYY-MM-DD, cd-ing into the volume directory first
         # contents of archive will be identical to contents of the PVC at time of archive creation, to simplify backup restore
-        # to restore a backup to the current folder: 'borg extract ${REPOSITORY}::YYYY-MM-DD-pvc.metadata.name'
-        # example backup command : borg create /mnt/repo::2020-02-01-sonarr .
-        # example restory command: borg extract /mnt/repo::2020-02-01-sonarr
+        # to restore a backup to the current folder: 'borg extract ${REPOSITORY}::pvc.metadata.name-YYYY-MM-DD'
+        # example backup command : borg create /mnt/repo::sonarr-2020-02-01 .
+        # example restory command: borg extract /mnt/repo::sonarr-2020-02-01
         subprocess.check_call(["borg", "create", "-v", "--stats", "--compression", "auto,zstd",
-                              f"{REPOSITORY}::{{now:%Y-%m-%d}}-{pvc_name}", "."],
+                              f"{REPOSITORY}::{pvc_name}-{{now:%Y-%m-%d}}", "."],
                               cwd=volume, env={"BORG_PASSPHRASE": BORG_PASSPHRASE})
+
+        # prune borg repo, removing old backups for this pvc_name
+        # note the --prefix, to limit pruning
+        subprocess.check_call(["borg", "prune", "-v", "--list", REPOSITORY, "--prefix", pvc_name,
+                              "--keep-daily=7", "--keep-weekly=4", "--keep-monthly=6", "--keep-yearly=1"],
+                              env={"BORG_PASSPHRASE": BORG_PASSPHRASE})