Add no-cache headers to avoid browser caching (#575)

Author: Dreamsorcerer

aiohttp_devtools/cli.py

@@ -26,19 +26,24 @@ def cli() -> None:
 verbose_help = 'Enable verbose output.'
 livereload_help = ('Whether to inject livereload.js into html page footers to autoreload on changes. '
                    'env variable AIO_LIVERELOAD')
+browser_cache_help = ("When disabled (the default), sends no-cache headers to "
+                      "disable browser caching.")
 
 
 @cli.command()
 @click.argument('path', type=_dir_existing, required=True)
 @click.option('--livereload/--no-livereload', envvar='AIO_LIVERELOAD', default=True, help=livereload_help)
 @click.option('-p', '--port', default=8000, type=int)
 @click.option('-v', '--verbose', is_flag=True, help=verbose_help)
-def serve(path: str, livereload: bool, port: int, verbose: bool) -> None:
+@click.option("--browser-cache/--no-browser-cache", envvar="AIO_BROWSER_CACHE", default=False,
+              help=browser_cache_help)
+def serve(path: str, livereload: bool, port: int, verbose: bool, browser_cache: bool) -> None:
     """
     Serve static files from a directory.
     """
     setup_logging(verbose)
-    run_app(**serve_static(static_path=path, livereload=livereload, port=port))
+    run_app(**serve_static(static_path=path, livereload=livereload, port=port,
+                           browser_cache=browser_cache))
 
 
 static_help = "Path of static files to serve, if excluded static files aren't served. env variable: AIO_STATIC_STATIC"
@@ -73,6 +78,8 @@ def serve(path: str, livereload: bool, port: int, verbose: bool) -> None:
 @click.option('-p', '--port', 'main_port', envvar='AIO_PORT', type=click.INT, help=port_help)
 @click.option('--aux-port', envvar='AIO_AUX_PORT', type=click.INT, help=aux_port_help)
 @click.option('-v', '--verbose', is_flag=True, help=verbose_help)
+@click.option("--browser-cache/--no-browser-cache", envvar="AIO_BROWSER_CACHE", default=None,
+              help=browser_cache_help)
 @click.argument('project_args', nargs=-1)
 def runserver(**config: Any) -> None:
     """

aiohttp_devtools/runserver/config.py

@@ -43,7 +43,8 @@ def __init__(self, *,
                  app_factory_name: Optional[str] = None,
                  host: str = INFER_HOST,
                  main_port: int = 8000,
-                 aux_port: Optional[int] = None):
+                 aux_port: Optional[int] = None,
+                 browser_cache: bool = False):
         if root_path:
             self.root_path = Path(root_path).resolve()
             logger.debug('Root path specified: %s', self.root_path)
@@ -75,6 +76,7 @@ def __init__(self, *,
         self.host = 'localhost' if self.infer_host else host
         self.main_port = main_port
         self.aux_port = aux_port or (main_port + 1)
+        self.browser_cache = browser_cache
         logger.debug('config loaded:\n%s', self)
 
     @property

aiohttp_devtools/runserver/main.py

@@ -66,10 +66,12 @@ def runserver(**config_kwargs: Any) -> RunServer:
             "shutdown_timeout": 0.01, "access_log_class": AuxAccessLogger}
 
 
-def serve_static(*, static_path: str, livereload: bool = True, port: int = 8000) -> RunServer:
+def serve_static(*, static_path: str, livereload: bool = True, port: int = 8000,
+                 browser_cache: bool = False) -> RunServer:
     logger.debug('Config: path="%s", livereload=%s, port=%s', static_path, livereload, port)
 
-    app = create_auxiliary_app(static_path=static_path, livereload=livereload)
+    app = create_auxiliary_app(static_path=static_path, livereload=livereload,
+                               browser_cache=browser_cache)
 
     if livereload:
         livereload_manager = LiveReloadTask(static_path)

aiohttp_devtools/runserver/serve.py

@@ -68,6 +68,16 @@ async def on_prepare(request: web.Request, response: web.StreamResponse) -> None
             response.headers[CONTENT_LENGTH] = str(len(response.body))
         app.on_response_prepare.append(on_prepare)
 
+    if not config.browser_cache:
+        @web.middleware
+        async def no_cache_middleware(request: web.Request, handler: Handler) -> web.StreamResponse:
+            """Add no-cache header to avoid browser caching in local development."""
+            response = await handler(request)
+            response.headers["Cache-Control"] = "no-cache"
+            return response
+
+        app.middlewares.append(no_cache_middleware)
+
     static_path = config.static_url.strip('/')
     if config.infer_host and config.static_path is not None:
         # we set the app key even in middleware to make the switch to production easier and for backwards compat.
@@ -226,7 +236,8 @@ async def cleanup_aux_app(app: web.Application) -> None:
 
 
 def create_auxiliary_app(
-        *, static_path: Optional[str], static_url: str = "/", livereload: bool = True) -> web.Application:
+        *, static_path: Optional[str], static_url: str = "/", livereload: bool = True,
+        browser_cache: bool = False) -> web.Application:
     app = web.Application()
     app[WS] = set()
     app.update(
@@ -248,7 +259,8 @@ def create_auxiliary_app(
             static_path + '/',
             name='static-router',
             add_tail_snippet=livereload,
-            follow_symlinks=True
+            follow_symlinks=True,
+            browser_cache=browser_cache
         )
         app.router.register_resource(route)
 
@@ -315,8 +327,10 @@ async def websocket_handler(request: web.Request) -> web.WebSocketResponse:
 
 
 class CustomStaticResource(StaticResource):
-    def __init__(self, *args: Any, add_tail_snippet: bool = False, **kwargs: Any):
+    def __init__(self, *args: Any, add_tail_snippet: bool = False,
+                 browser_cache: bool = False, **kwargs: Any):
         self._add_tail_snippet = add_tail_snippet
+        self._browser_cache = browser_cache
         super().__init__(*args, **kwargs)
         self._show_index = True
 
@@ -377,7 +391,8 @@ async def _handle(self, request: web.Request) -> web.StreamResponse:
             # Inject CORS headers to allow webfonts to load correctly
             response.headers['Access-Control-Allow-Origin'] = '*'
 
-        # Add no-cache header to avoid browser caching in local development.
-        response.headers["Cache-Control"] = "no-cache"
+        if not self._browser_cache:
+            # Add no-cache header to avoid browser caching in local development.
+            response.headers["Cache-Control"] = "no-cache"
 
         return response

tests/test_runserver_main.py

@@ -123,10 +123,24 @@ async def test_run_app_aiohttp_client(tmpworkdir, aiohttp_client):
     cli = await aiohttp_client(app)
     r = await cli.get('/')
     assert r.status == 200
+    assert r.headers["Cache-Control"] == "no-cache"
     text = await r.text()
     assert text == 'hello world'
 
 
+@forked
+async def test_run_app_browser_cache(tmpworkdir, aiohttp_client):
+    mktree(tmpworkdir, SIMPLE_APP)
+    config = Config(app_path="app.py", browser_cache=True)
+    app_factory = config.import_app_factory()
+    app = await config.load_app(app_factory)
+    modify_main_app(app, config)
+    cli = await aiohttp_client(app)
+    r = await cli.get("/")
+    assert r.status == 200
+    assert "Cache-Control" not in r.headers
+
+
 async def test_aux_app(tmpworkdir, aiohttp_client):
     mktree(tmpworkdir, {
         'test.txt': 'test value',

tests/test_runserver_serve.py

@@ -136,7 +136,8 @@ def add_subapp(self, path, app):
 
 def test_modify_main_app_all_off(tmpworkdir):
     mktree(tmpworkdir, SIMPLE_APP)
-    config = Config(app_path='app.py', livereload=False, host='foobar.com', static_path='.')
+    config = Config(app_path="app.py", livereload=False, host="foobar.com",
+                    static_path=".", browser_cache=True)
     app = DummyApplication()
     subapp = DummyApplication()
     app.add_subapp("/sub/", subapp)
@@ -156,7 +157,7 @@ def test_modify_main_app_all_on(tmpworkdir):
     app.add_subapp("/sub/", subapp)
     modify_main_app(app, config)  # type: ignore[arg-type]
     assert len(app.on_response_prepare) == 1
-    assert len(app.middlewares) == 1
+    assert len(app.middlewares) == 2
     assert app['static_root_url'] == 'http://localhost:8001/static'
     assert subapp['static_root_url'] == "http://localhost:8001/static"
     assert app._debug is True

tests/test_serve.py

@@ -21,6 +21,7 @@ async def test_simple_serve(cli, tmpworkdir):
     assert r.status == 200
     assert r.headers['content-type'] == 'application/octet-stream'
     assert 'Access-Control-Allow-Origin' in r.headers and r.headers['Access-Control-Allow-Origin'] == '*'
+    assert r.headers["Cache-Control"] == "no-cache"
     text = await r.text()
     assert text == 'hello world'
 
@@ -32,6 +33,16 @@ async def test_file_missing(cli):
     assert '404: Not Found\n' in text
 
 
+async def test_browser_cache(event_loop, aiohttp_client, tmpworkdir):
+    args = serve_static(static_path=str(tmpworkdir), browser_cache=True)
+    assert args["port"] == 8000
+    cli = await aiohttp_client(args["app"])
+    mktree(tmpworkdir, {"foo": "hello world"})
+    r = await cli.get("/foo")
+    assert r.status == 200
+    assert "Cache-Control" not in r.headers
+
+
 async def test_html_file_livereload(event_loop, aiohttp_client, tmpworkdir):
     args = serve_static(static_path=str(tmpworkdir), livereload=True)
     assert args["port"] == 8000