fix: altair now works in voila

Fixes #486

We now default to not using the CDN proxy when we detect we are running
in voila.

solara/settings.py

@@ -39,7 +39,7 @@ class Config:
 
 
 # in colab or vscode there is not solara cdn proxy available
-_should_use_proxy = not (solara.util.is_running_in_colab() or solara.util.is_running_in_vscode())
+_should_use_proxy = not (solara.util.is_running_in_colab() or solara.util.is_running_in_vscode() or solara.util.is_running_in_voila())
 
 
 class Assets(BaseSettings):

solara/util.py

@@ -280,3 +280,7 @@ def is_running_in_colab():
 
 def is_running_in_vscode():
     return "VSCODE_PID" in os.environ or "VSCODE_CWD" in os.environ
+
+
+def is_running_in_voila():
+    return os.environ.get("SERVER_SOFTWARE", "").startswith("voila")

tests/integration/cdn_test.py

@@ -10,9 +10,6 @@
 def test_cdn_via_altair(ipywidgets_runner, page_session: playwright.sync_api.Page, request, assert_solara_snapshot):
     if request.node.callspec.params["ipywidgets_runner"] != "solara" and request.node.callspec.params["solara_server"] != SERVERS[0]:
         pytest.skip("No need to run this test for all servers.")
-    if request.node.callspec.params["ipywidgets_runner"] == "voila":
-        # see https://github.com/widgetti/solara/issues/486
-        pytest.skip("Does not work with Voila.")
 
     # this function (or rather its lines) will be executed in the kernel
     # voila, lab, classic notebook and solara will all execute it