Add verified Prometheus backup pull to Atlas

ansible/roles/profile_atlas/files/atlas-prometheus-prune.py

@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+"""Prune only verified, named Prometheus backup versions after publication."""
+
+import datetime as dt
+import pathlib
+import re
+import shutil
+import sys
+
+
+def main() -> None:
+    if len(sys.argv) != 5:
+        raise SystemExit("Usage: atlas-prometheus-prune SNAPSHOTS DAILY WEEKLY MONTHLY")
+    root = pathlib.Path(sys.argv[1])
+    counts = [int(value) for value in sys.argv[2:]]
+    if not root.is_dir() or root.is_symlink() or min(counts) < 1:
+        raise SystemExit("Invalid backup directory or retention counts")
+    versions = []
+    for entry in root.iterdir():
+        if not entry.is_dir() or entry.is_symlink():
+            continue
+        if not re.fullmatch(r"[0-9]{8}T[0-9]{6}Z", entry.name):
+            continue
+        try:
+            when = dt.datetime.strptime(entry.name, "%Y%m%dT%H%M%SZ")
+        except ValueError:
+            continue
+        if not all((entry / name).is_file() for name in ("payload.tar", "payload.sha256", "metadata.json")):
+            continue
+        versions.append((when, entry))
+    versions.sort(reverse=True)
+    if not versions:
+        raise SystemExit("No published backup versions found; refusing to prune")
+
+    keep = {entry for _, entry in versions[: counts[0]]}
+    for count, key in (
+        (counts[1], lambda when: when.isocalendar()[:2]),
+        (counts[2], lambda when: (when.year, when.month)),
+    ):
+        periods = set()
+        for when, entry in versions:
+            period = key(when)
+            if period in periods:
+                continue
+            periods.add(period)
+            keep.add(entry)
+            if len(periods) >= count:
+                break
+
+    for _, entry in versions:
+        if entry not in keep:
+            shutil.rmtree(entry)
+
+
+if __name__ == "__main__":
+    main()