make caching opt-in

.env.example

@@ -5,8 +5,9 @@ GITEA_BASE_URL=https://gitea.example.com
 GITEA_USERNAME=octocat
 GITEA_TOKEN=
 
-CACHE_TTL_SECONDS=3600
-CACHE_DIR=/app/cache
+# Leave both unset to disable caching.
+# CACHE_TTL_SECONDS=3600
+# CACHE_DIR=/app/cache
 
 DEFAULT_THEME=light
 SERVICE_TITLE=git-activity-merge

README.md

@@ -68,11 +68,12 @@ Optional:
 
 - `GITHUB_TOKEN`
 - `GITEA_TOKEN`
-- `CACHE_TTL_SECONDS` (default: `3600`)
-- `CACHE_DIR` (default: `./cache` locally, `/app/cache` in container)
+- `CACHE_TTL_SECONDS` and `CACHE_DIR` enable caching when both are set
 - `DEFAULT_THEME` (`light` or `dark`, default: `light`)
 - `SERVICE_TITLE` (default: `git-activity-merge`)
 
+If you leave `CACHE_TTL_SECONDS` and `CACHE_DIR` undefined, the app skips caching entirely.
+
 ### 3. Run
 
 ```bash

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:
@@ -213,6 +219,7 @@ 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)
+    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")
@@ -227,6 +234,7 @@ async def activity_svg(
         total_contributions=total,
         theme=options.theme,
     )
+    if cache is not None:
         cache.set_json(cache_key, svg)
     return Response(content=svg, media_type="image/svg+xml")
 
@@ -234,7 +242,7 @@ async def activity_svg(
 @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:
@@ -244,6 +252,7 @@ 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)
+    if cache is not None:
         cached = cache.get_json(cache_key)
         if cached is not None:
             png_data = bytes.fromhex(str(cached.value))
@@ -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
+    if cache is not None:
         cache.set_json(cache_key, png_data.hex())
     return Response(content=png_data, media_type="image/png")

app/settings.py

@@ -14,8 +14,8 @@ class Settings(BaseSettings):
     gitea_username: str = Field(alias="GITEA_USERNAME")
     gitea_token: str | None = Field(default=None, alias="GITEA_TOKEN")
 
-    cache_ttl_seconds: int = Field(default=3600, alias="CACHE_TTL_SECONDS")
-    cache_dir: str = Field(default="./cache", alias="CACHE_DIR")
+    cache_ttl_seconds: int | None = Field(default=None, alias="CACHE_TTL_SECONDS")
+    cache_dir: str | None = Field(default=None, alias="CACHE_DIR")
 
     default_theme: str = Field(default="light", alias="DEFAULT_THEME")
     service_title: str = Field(default="git-activity-merge", alias="SERVICE_TITLE")

tests/test_cache.py

@@ -1,10 +1,16 @@
 import time
 
+import tempfile
+from pathlib import Path
+
 from app.cache import FileCache
+from app.main import get_cache
+from app.settings import Settings
 
 
-def test_cache_returns_fresh_entry(tmp_path) -> None:
-    cache = FileCache(cache_dir=str(tmp_path), default_ttl_seconds=10)
+def test_cache_returns_fresh_entry() -> None:
+    with tempfile.TemporaryDirectory(dir=Path.cwd()) as temp_dir:
+        cache = FileCache(cache_dir=temp_dir, default_ttl_seconds=10)
         cache.set_json("sample", {"x": 1})
 
         entry = cache.get_json("sample")
@@ -14,8 +20,9 @@ def test_cache_returns_fresh_entry(tmp_path) -> None:
         assert entry.value == {"x": 1}
 
 
-def test_cache_can_serve_stale_when_requested(tmp_path) -> None:
-    cache = FileCache(cache_dir=str(tmp_path), default_ttl_seconds=0)
+def test_cache_can_serve_stale_when_requested() -> None:
+    with tempfile.TemporaryDirectory(dir=Path.cwd()) as temp_dir:
+        cache = FileCache(cache_dir=temp_dir, default_ttl_seconds=0)
         cache.set_json("sample", {"x": 1})
         time.sleep(0.01)
 
@@ -26,3 +33,26 @@ def test_cache_can_serve_stale_when_requested(tmp_path) -> None:
         assert stale is not None
         assert stale.stale is True
         assert stale.value == {"x": 1}
+
+
+def test_cache_is_disabled_when_not_configured() -> None:
+    settings = Settings(
+        _env_file=None,
+        GITHUB_USERNAME="octocat",
+        GITEA_BASE_URL="https://gitea.example.com",
+        GITEA_USERNAME="octocat",
+    )
+
+    cache = get_cache(settings)
+
+    assert cache is None
+
+
+def test_cache_works_in_workspace_tempdir() -> None:
+    with tempfile.TemporaryDirectory(dir=Path.cwd()) as temp_dir:
+        cache = FileCache(cache_dir=temp_dir, default_ttl_seconds=10)
+        cache.set_json("sample", {"x": 1})
+        entry = cache.get_json("sample")
+
+        assert entry is not None
+        assert entry.value == {"x": 1}

tests/test_routes.py

@@ -1,3 +1,5 @@
+import tempfile
+from pathlib import Path
 from datetime import date
 
 from fastapi.testclient import TestClient
@@ -6,11 +8,12 @@ from app.main import ActivityResult, app
 from app.settings import get_settings
 
 
-def test_activity_svg_returns_svg_content_type(monkeypatch, tmp_path) -> None:
+def test_activity_svg_returns_svg_content_type(monkeypatch) -> None:
     monkeypatch.setenv("GITHUB_USERNAME", "octocat")
     monkeypatch.setenv("GITEA_BASE_URL", "https://gitea.example.com")
     monkeypatch.setenv("GITEA_USERNAME", "octocat")
-    monkeypatch.setenv("CACHE_DIR", str(tmp_path))
+    with tempfile.TemporaryDirectory(dir=Path.cwd()) as temp_dir:
+        monkeypatch.setenv("CACHE_DIR", temp_dir)
         get_settings.cache_clear()
 
         async def fake_collect_merged_activity(settings, cache, options):