Add frontend dev proxy for WDS

homeassistant/components/frontend/__init__.py

@@ -341,6 +341,11 @@ async def async_setup(hass: HomeAssistant, config: ConfigType) -> bool:
     is_dev = repo_path is not None
     root_path = _frontend_root(repo_path)
 
+    if is_dev:
+        from .dev import async_setup_frontend_dev
+
+        async_setup_frontend_dev(hass)
+
     for path, should_cache in (
         ("service_worker.js", False),
         ("robots.txt", False),

homeassistant/components/frontend/dev.py

@@ -0,0 +1,60 @@
+"""Development helpers for the frontend."""
+import aiohttp
+from aiohttp import hdrs, web
+
+from homeassistant.components.http.view import HomeAssistantView
+from homeassistant.core import HomeAssistant, callback
+from homeassistant.helpers import aiohttp_client
+
+
+@callback
+def async_setup_frontend_dev(hass: HomeAssistant) -> None:
+    """Set up frontend dev views."""
+    hass.http.register_view(  # type: ignore
+        FrontendDevView(
+            "http://localhost:8000", aiohttp_client.async_get_clientsession(hass)
+        )
+    )
+
+
+FILTER_RESPONSE_HEADERS = {hdrs.CONTENT_LENGTH, hdrs.CONTENT_ENCODING}
+
+
+class FrontendDevView(HomeAssistantView):
+    """Frontend dev view."""
+
+    name = "_dev:frontend"
+    url = "/_dev_frontend/{path:.*}"
+    requires_auth = False
+    extra_urls = ["/__web-dev-server__/{path:.*}"]
+
+    def __init__(self, forward_base: str, websession: aiohttp.ClientSession):
+        """Initialize a Hass.io ingress view."""
+        self._forward_base = forward_base
+        self._websession = websession
+
+    async def get(self, request: web.Request, path: str) -> web.Response:
+        """Frontend routing."""
+        # To deal with: import * as commonjsHelpers from '/__web-dev-server__/rollup/commonjsHelpers.js
+        if request.path.startswith("/__web-dev-server__/"):
+            path = f"__web-dev-server__/{path}"
+
+        url = f"{self._forward_base}/{path}"
+
+        if request.query_string:
+            url += f"?{request.query_string}"
+
+        async with self._websession.get(
+            url,
+            headers=request.headers,
+            allow_redirects=False,
+        ) as result:
+            return web.Response(
+                headers={
+                    hdr: val
+                    for hdr, val in result.headers.items()
+                    if hdr not in FILTER_RESPONSE_HEADERS
+                },
+                status=result.status,
+                body=await result.read(),
+            )