prune --keep-all: alias for --keep-last <inf>, fixes #6656

src/borg/archiver/prune_cmd.py

@@ -138,9 +138,29 @@ def do_prune(self, args, repository, manifest):
                 'At least one of the "keep-within", "keep-last", '
                 '"keep-secondly", "keep-minutely", "keep-hourly", "keep-daily", '
                 '"keep-weekly", "keep-monthly", "keep-13weekly", "keep-3monthly", '
-                'or "keep-yearly" settings must be specified.'
+                '"keep-yearly", or "keep-all" settings must be specified.'
             )
 
+        # --keep-all is an alias for --keep-last=<infinite> and must not be
+        # used together with any other --keep-... option, because that would be
+        # misleading. Enforce this at argument parsing/validation time.
+        keep_all = args.secondly == float("inf")
+        if keep_all:
+            if any(
+                (
+                    args.minutely,
+                    args.hourly,
+                    args.daily,
+                    args.weekly,
+                    args.monthly,
+                    args.quarterly_13weekly,
+                    args.quarterly_3monthly,
+                    args.yearly,
+                    args.within,
+                )
+            ):
+                raise CommandError("--keep-all cannot be combined with other --keep-... options.")
+
         if args.format is not None:
             format = args.format
         elif args.short:
@@ -320,6 +340,13 @@ def build_parser_prune(self, subparsers, common_parser, mid_common_parser):
             action=Highlander,
             help="number of secondly archives to keep",
         )
+        subparser.add_argument(
+            "--keep-all",
+            dest="secondly",
+            action="store_const",
+            const=float("inf"),
+            help="keep all archives (alias of --keep-last=<infinite>)",
+        )
         subparser.add_argument(
             "--keep-minutely",
             dest="minutely",

src/borg/testsuite/archiver/prune_cmd_test.py

@@ -6,7 +6,7 @@
 from ...constants import *  # NOQA
 from ...archiver.prune_cmd import prune_split, prune_within
 from . import cmd, RK_ENCRYPTION, src_dir, generate_archiver_tests
-from ...helpers import interval
+from ...helpers import interval, CommandError
 
 pytest_generate_tests = lambda metafunc: generate_archiver_tests(metafunc, kinds="local,remote,binary")  # NOQA
 
@@ -272,6 +272,76 @@ def __repr__(self):
         return f"{self.id}: {self.ts.isoformat()}"
 
 
+def test_prune_keep_all(archivers, request):
+    archiver = request.getfixturevalue(archivers)
+    cmd(archiver, "repo-create", RK_ENCRYPTION)
+    # create a few archives with distinct seconds so 'secondly' rule can keep all
+    _create_archive_ts(archiver, "a1", 2025, 1, 1, 0, 0, 0)
+    _create_archive_ts(archiver, "a2", 2025, 1, 1, 0, 0, 1)
+    _create_archive_ts(archiver, "a3", 2025, 1, 1, 0, 0, 2)
+
+    # Dry-run prune: nothing should be pruned, all should be kept under 'secondly' rule
+    output = cmd(archiver, "prune", "--list", "--dry-run", "--keep-all")
+    assert re.search(r"Keeping archive \(rule: secondly(?:\[oldest\])? #\d+\):\s+a1", output)
+    assert re.search(r"Keeping archive \(rule: secondly(?:\[oldest\])? #\d+\):\s+a2", output)
+    assert re.search(r"Keeping archive \(rule: secondly(?:\[oldest\])? #\d+\):\s+a3", output)
+    assert "Would prune:" not in output
+    assert "Pruning archive" not in output
+    output = cmd(archiver, "repo-list", "--format", "{name}{NL}")
+    names = set(output.splitlines())
+    assert names == {"a1", "a2", "a3"}
+
+    # Real prune with --keep-all should also not delete anything
+    cmd(archiver, "prune", "--keep-all")
+    output = cmd(archiver, "repo-list", "--format", "{name}{NL}")
+    names = set(output.splitlines())
+    assert names == {"a1", "a2", "a3"}
+
+
+def test_prune_keep_all_mutually_exclusive_with_others(archivers, request):
+    archiver = request.getfixturevalue(archivers)
+    cmd(archiver, "repo-create", RK_ENCRYPTION)
+    # create a single archive
+    _create_archive_ts(archiver, "x1", 2025, 1, 1, 0, 0, 0)
+    # Using --keep-all together with any other keep option must error out
+    output = cmd(archiver, "prune", "--keep-all", "--keep-daily=1", exit_code=CommandError().exit_code, fork=True)
+    assert "--keep-all cannot be combined" in output
+
+
+def test_prune_keep_all_mutually_exclusive_with_within(archivers, request):
+    archiver = request.getfixturevalue(archivers)
+    cmd(archiver, "repo-create", RK_ENCRYPTION)
+    _create_archive_ts(archiver, "x1", 2025, 1, 1, 0, 0, 0)
+    output = cmd(archiver, "prune", "--keep-all", "--keep-within", "1d", exit_code=CommandError().exit_code, fork=True)
+    assert "--keep-all cannot be combined" in output
+
+
+def test_prune_keep_all_and_keep_last_2(archivers, request):
+    # Problem: --keep-all, --keep-secondly and --keep-last=X use the same variable
+    archiver = request.getfixturevalue(archivers)
+    cmd(archiver, "repo-create", RK_ENCRYPTION)
+    # Create three archives with distinct seconds
+    _create_archive_ts(archiver, "c1", 2025, 1, 1, 0, 0, 0)
+    _create_archive_ts(archiver, "c2", 2025, 1, 1, 0, 0, 1)
+    _create_archive_ts(archiver, "c3", 2025, 1, 1, 0, 0, 2)
+
+    # Dry-run prune: with conflicting options, keep-all dominates
+    output = cmd(archiver, "prune", "--list", "--dry-run", "--keep-all", "--keep-last=2")
+    # Expect all kept under 'secondly' rule, nothing would be pruned
+    assert re.search(r"Keeping archive \(rule: secondly(?:\[oldest\])? #\d+\):\s+c1", output)
+    assert re.search(r"Keeping archive \(rule: secondly(?:\[oldest\])? #\d+\):\s+c2", output)
+    assert re.search(r"Keeping archive \(rule: secondly(?:\[oldest\])? #\d+\):\s+c3", output)
+    assert "Would prune:" not in output
+
+    # Dry-run prune: with conflicting options, keep-all dominates
+    output = cmd(archiver, "prune", "--list", "--dry-run", "--keep-last=2", "--keep-all")
+    # Expect all kept under 'secondly' rule, nothing would be pruned
+    assert re.search(r"Keeping archive \(rule: secondly(?:\[oldest\])? #\d+\):\s+c1", output)
+    assert re.search(r"Keeping archive \(rule: secondly(?:\[oldest\])? #\d+\):\s+c2", output)
+    assert re.search(r"Keeping archive \(rule: secondly(?:\[oldest\])? #\d+\):\s+c3", output)
+    assert "Would prune:" not in output
+
+
 # This is the local timezone of the system running the tests.
 # We need this e.g. to construct archive timestamps for the prune tests,
 # because borg prune operates in the local timezone (it first converts the