US08-02: Build a Reproducible Application Image (#97)

photo_pipeline/integrations/exiftool.py

@@ -12,8 +12,10 @@ nt-apply-list, pa-nsfw-filter). No dependency on the archived entry points.
 
 from __future__ import annotations
 
+import functools
 import json
 import os
+import shutil
 import subprocess
 from collections.abc import Iterable
 
@@ -32,6 +34,27 @@ def _timeout() -> float:
         return DEFAULT_TIMEOUT_SECONDS
 
 
+def find_binary(binary: str = "exiftool") -> str | None:
+    """Absolute path of exiftool, or ``None`` when it is not installed."""
+    return shutil.which(binary)
+
+
+@functools.lru_cache(maxsize=1)
+def version() -> str | None:
+    """Reported exiftool version, or ``None`` when it is missing or unusable.
+
+    Cached: it cannot change inside a running process, and diagnostics asks for it
+    on every report (US08-02, where a container image pins this version).
+    """
+    try:
+        result = subprocess.run(
+            ["exiftool", "-ver"], capture_output=True, text=True, timeout=_timeout()
+        )
+    except (OSError, subprocess.SubprocessError):
+        return None
+    return (result.stdout or "").strip() or None
+
+
 def read_keyword_sets(paths: Iterable[str]) -> dict[str, set[str]]:
     """Map each path to its lowercased set of ``Keywords`` + ``Subject`` values.