add retention policies

resticbackup/cli.py

@@ -144,17 +144,67 @@ def cmd_backup(args, parser):
                 raise Exception(stdout)
 
             # run backup
-            backup_cmd = [RESTIC_BIN, "backup", "./", "--json"]
+            backup_cmd = [RESTIC_BIN, "backup", "./"]
             for k, v in backup_tags.items():
                 backup_cmd.append("--tag")
                 backup_cmd.append("{}={}".format(k, v))
 
-            proc = subprocess.Popen(backup_cmd, env=env, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
-            stdout, _ = proc.communicate(input=None, timeout=None)
-            stdout = stdout.decode()
+            proc = subprocess.Popen(backup_cmd, env=env)
+            proc.communicate(input=None, timeout=None)
 
     # perform retention
+    schedule = backup_config.get('schedule')
+    if not schedule:
+        return
 
+    retention_args = get_retention_args(schedule)
+    if not retention_args:
+        return
+
+    proc = subprocess.Popen([RESTIC_BIN, "forget"] + retention_args, env=env)
+    proc.communicate(input=None, timeout=None)
+
+    # perform junk deletion
+    proc = subprocess.Popen([RESTIC_BIN, "prune"], env=env)
+    proc.communicate(input=None, timeout=None)
+
+
+def get_retention_args(schedule):
+    """
+    given a retention schedule, return restic command(s) needed to make it so
+    """
+    mode = schedule["function"]
+    if mode == "forever":
+        # do not perform deletions
+        return None
+    elif mode == "keep":
+        # just keep the last X snapshots
+        return ["--keep-last", str(mode["count"])]
+    elif mode == "cycle":
+        # keep the last $last backups.
+        # keep a daily backup after that for the past $daily days.
+        # keep a weekly backup after that for the past $weekly weeks.
+        # keep a monthly backup after that for the past $monthly months.
+        cmd = []
+        last = schedule.get("last")
+        if last is not None:
+            cmd.extend(["--keep-last", str(last)])
+
+        daily = schedule.get("daily")
+        if daily is not None:
+            cmd.extend(["--keep-daily", str(daily)])
+
+        weekly = schedule.get("weekly")
+        if weekly is not None:
+            cmd.extend(["--keep-weekly", str(weekly)])
+
+        monthly = schedule.get("monthly")
+        if monthly is not None:
+            cmd.extend(["--keep-monthly", str(monthly)])
+
+        return cmd or None
+    else:
+        raise Exception("unknown retention function {}".format(mode))
 
 
 def cmd_restore(args, parser):