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:
@@ -213,9 +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")

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

@@ -1,28 +1,58 @@
 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)
-    cache.set_json("sample", {"x": 1})
+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")
+        entry = cache.get_json("sample")
 
-    assert entry is not None
-    assert entry.stale is False
-    assert entry.value == {"x": 1}
+        assert entry is not None
+        assert entry.stale is False
+        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)
-    cache.set_json("sample", {"x": 1})
-    time.sleep(0.01)
+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)
 
-    fresh = cache.get_json("sample")
-    stale = cache.get_json("sample", allow_stale=True)
+        fresh = cache.get_json("sample")
+        stale = cache.get_json("sample", allow_stale=True)
 
-    assert fresh is None
-    assert stale is not None
-    assert stale.stale is True
-    assert stale.value == {"x": 1}
+        assert fresh is 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
@@ -6,30 +8,31 @@ 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))
-    get_settings.cache_clear()
+    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):
-        return ActivityResult(
-            merged={
-                "2026-01-01": {"github": 1, "gitea": 2, "total": 3},
-                "2026-01-02": {"github": 0, "gitea": 0, "total": 0},
-            },
-            stale=False,
-            from_date=date(2026, 1, 1),
-            to_date=date(2026, 1, 2),
-            days_count=2,
-        )
+        async def fake_collect_merged_activity(settings, cache, options):
+            return ActivityResult(
+                merged={
+                    "2026-01-01": {"github": 1, "gitea": 2, "total": 3},
+                    "2026-01-02": {"github": 0, "gitea": 0, "total": 0},
+                },
+                stale=False,
+                from_date=date(2026, 1, 1),
+                to_date=date(2026, 1, 2),
+                days_count=2,
+            )
 
-    monkeypatch.setattr("app.main.collect_merged_activity", fake_collect_merged_activity)
+        monkeypatch.setattr("app.main.collect_merged_activity", fake_collect_merged_activity)
 
-    client = TestClient(app)
-    response = client.get("/activity.svg")
+        client = TestClient(app)
+        response = client.get("/activity.svg")
 
-    assert response.status_code == 200
-    assert response.headers["content-type"].startswith("image/svg+xml")
-    assert "<svg" in response.text
+        assert response.status_code == 200
+        assert response.headers["content-type"].startswith("image/svg+xml")
+        assert "<svg" in response.text