fix: serve launcher icons for svg and png

docs/source/server-process.md

@@ -121,10 +121,8 @@ the following keys:
    Set to True (default) to make an entry in the launchers. Set to False to have no
    explicit entry.
 2. **icon_path**
-   Full path to an svg icon that could be used with a launcher. Currently only used by the
-   JupyterLab launcher, when category is "Notebook" (default) or "Console". Only text-based icon
-   formats, such as SVG, are supported. Using binary-based formats like PNG or JPEG will
-   result in an empty icon being displayed in kernels.
+   Full path to an icon file that could be used with a launcher (for example, `.svg` or `.png`).
+   Currently only used by the JupyterLab launcher, when category is "Notebook" (default) or "Console".
 3. **title**
    Title to be used for the launcher entry. Defaults to the name of the server if missing.
 4. **path_info**

jupyter_server_proxy/api.py

@@ -68,6 +68,6 @@ async def get(self, name):
         else:
             content_type = "application/octet-stream"
 
-        with open(self.icons[name]) as f:
+        with open(self.icons[name], "rb") as f:
             self.write(f.read())
         self.set_header("Content-Type", content_type)

tests/resources/jupyter_server_config.py

@@ -55,6 +55,18 @@ def my_env():
     "python-http": {
         "command": [sys.executable, _get_path("httpinfo.py"), "--port={port}"],
     },
+    "python-http-icon-svg": {
+        "command": [sys.executable, _get_path("httpinfo.py"), "--port={port}"],
+        "launcher_entry": {
+            "icon_path": _get_path("icon.svg"),
+        },
+    },
+    "python-http-icon-png": {
+        "command": [sys.executable, _get_path("httpinfo.py"), "--port={port}"],
+        "launcher_entry": {
+            "icon_path": _get_path("icon.png"),
+        },
+    },
     "python-http-abs": {
         "command": [sys.executable, _get_path("httpinfo.py"), "--port={port}"],
         "absolute_url": True,

tests/test_proxies.py

@@ -593,3 +593,35 @@ def test_server_proxy_redirect_location_header_absolute_url(
     # Backend returns whatever it wants, proxy doesn't rewrite it
     # In this case, backend adds trailing slash to the full path it received
     assert location == f"/python-redirect-abs/abc/?token={TOKEN}"
+
+
+def test_server_proxy_icon_handler_svg(
+    a_server_port_and_token: Tuple[int, str],
+) -> None:
+    PORT, TOKEN = a_server_port_and_token
+
+    r = request_get(PORT, "/server-proxy/icon/python-http-icon-svg", TOKEN)
+    assert r.code == 200
+
+    content_type = r.headers.get("Content-Type")
+    assert content_type is not None
+    assert content_type.startswith("image/svg")
+
+    body = r.read().decode("utf-8")
+    assert "<svg" in body
+
+
+def test_server_proxy_icon_handler_png(
+    a_server_port_and_token: Tuple[int, str],
+) -> None:
+    PORT, TOKEN = a_server_port_and_token
+
+    r = request_get(PORT, "/server-proxy/icon/python-http-icon-png", TOKEN)
+    assert r.code == 200
+
+    content_type = r.headers.get("Content-Type")
+    assert content_type is not None
+    assert content_type.startswith("image/png")
+
+    body = r.read()
+    assert body.startswith(b"\x89PNG\r\n\x1a\n")