make caching opt-in

app/main.py

@@ -43,7 +43,9 @@ class ActivityResult:
 app = FastAPI(title=os.getenv("SERVICE_TITLE", "git-activity-merge"))
 
 
-def get_cache(settings: Settings = Depends(get_settings)) -> FileCache:
+def get_cache(settings: Settings = Depends(get_settings)) -> FileCache | None:
+    if settings.cache_dir is None or settings.cache_ttl_seconds is None:
+        return None
     return FileCache(cache_dir=settings.cache_dir, default_ttl_seconds=settings.cache_ttl_seconds)
 
 
@@ -88,10 +90,14 @@ def _date_keys(from_date: date, to_date: date) -> list[str]:
 
 
 async def _fetch_with_cache(
-    cache: FileCache,
+    cache: FileCache | None,
     key: str,
     fetcher,
 ) -> tuple[dict[str, int], bool]:
+    if cache is None:
+        fresh = await fetcher()
+        return fresh, False
+
     cached = cache.get_json(key, allow_stale=True)
     if cached and not cached.stale:
         return {k: int(v) for k, v in cached.value.items()}, False
@@ -109,7 +115,7 @@ async def _fetch_with_cache(
 
 async def collect_merged_activity(
     settings: Settings,
-    cache: FileCache,
+    cache: FileCache | None,
     options: QueryOptions,
 ) -> ActivityResult:
     from_date, to_date, days_count = compute_date_range(options)
@@ -178,7 +184,7 @@ async def health(settings: Settings = Depends(get_settings)) -> dict[str, str]:
 @app.get("/activity.json")
 async def activity_json(
     settings: Settings = Depends(get_settings),
-    cache: FileCache = Depends(get_cache),
+    cache: FileCache | None = Depends(get_cache),
     options: QueryOptions = Depends(get_query_options),
 ) -> JSONResponse:
     try:
@@ -203,7 +209,7 @@ async def activity_json(
 @app.get("/activity.svg")
 async def activity_svg(
     settings: Settings = Depends(get_settings),
-    cache: FileCache = Depends(get_cache),
+    cache: FileCache | None = Depends(get_cache),
     options: QueryOptions = Depends(get_query_options),
 ) -> Response:
     try:
@@ -213,9 +219,10 @@ async def activity_svg(
         raise HTTPException(status_code=502, detail="Failed to fetch activity data") from exc
 
     cache_key = _image_cache_key("svg", options, result)
-    cached = cache.get_json(cache_key)
-    if cached is not None:
-        return Response(content=str(cached.value), media_type="image/svg+xml")
+    if cache is not None:
+        cached = cache.get_json(cache_key)
+        if cached is not None:
+            return Response(content=str(cached.value), media_type="image/svg+xml")
 
     daily_totals = _daily_totals(result.merged)
     total = sum(daily_totals.values())
@@ -227,14 +234,15 @@ async def activity_svg(
         total_contributions=total,
         theme=options.theme,
     )
-    cache.set_json(cache_key, svg)
+    if cache is not None:
+        cache.set_json(cache_key, svg)
     return Response(content=svg, media_type="image/svg+xml")
 
 
 @app.get("/activity.png")
 async def activity_png(
     settings: Settings = Depends(get_settings),
-    cache: FileCache = Depends(get_cache),
+    cache: FileCache | None = Depends(get_cache),
     options: QueryOptions = Depends(get_query_options),
 ) -> Response:
     try:
@@ -244,10 +252,11 @@ async def activity_png(
         raise HTTPException(status_code=502, detail="Failed to fetch activity data") from exc
 
     cache_key = _image_cache_key("png", options, result)
-    cached = cache.get_json(cache_key)
-    if cached is not None:
-        png_data = bytes.fromhex(str(cached.value))
-        return Response(content=png_data, media_type="image/png")
+    if cache is not None:
+        cached = cache.get_json(cache_key)
+        if cached is not None:
+            png_data = bytes.fromhex(str(cached.value))
+            return Response(content=png_data, media_type="image/png")
 
     daily_totals = _daily_totals(result.merged)
     total = sum(daily_totals.values())
@@ -264,5 +273,6 @@ async def activity_png(
     except Exception as exc:
         logger.exception("failed to render png")
         raise HTTPException(status_code=500, detail="PNG rendering failed") from exc
-    cache.set_json(cache_key, png_data.hex())
+    if cache is not None:
+        cache.set_json(cache_key, png_data.hex())
     return Response(content=png_data, media_type="image/png")