Add CORS header to Element's map_style.json for Element Desktop

Element Desktop (Electron) loads the location-sharing map style from a
`vector://vector` origin, so fetching map_style.json from the Element
domain is a cross-origin request. Without an Access-Control-Allow-Origin
header, the request is blocked and maps fail to load with "This homeserver
is not configured correctly to display maps".

Add a dedicated Traefik router for map_style.json that attaches an
Access-Control-Allow-Origin header (configurable via
matrix_client_element_location_sharing_map_style_access_control_allow_origin,
defaulting to `*`). It is only defined when location sharing is enabled.

Fixes #2291

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Slavi Pantaleev
2026-07-13 08:58:52 +03:00
parent d0f877fb86
commit b32272ef40
2 changed files with 21 additions and 0 deletions
@@ -51,6 +51,23 @@ traefik.http.routers.matrix-client-element.tls={{ matrix_client_element_containe
traefik.http.routers.matrix-client-element.tls.certResolver={{ matrix_client_element_container_labels_traefik_tls_certResolver }}
{% endif %}
{% if matrix_client_element_location_sharing_enabled %}
{#
A dedicated router for the map style file, which attaches an Access-Control-Allow-Origin header.
Element Desktop loads the map style from a `vector://vector` origin, so it needs to be allowed cross-origin access.
#}
traefik.http.middlewares.matrix-client-element-map-style-add-headers.headers.customresponseheaders.Access-Control-Allow-Origin={{ matrix_client_element_location_sharing_map_style_access_control_allow_origin }}
traefik.http.routers.matrix-client-element-map-style.rule={{ matrix_client_element_container_labels_traefik_rule }} && Path(`{{ (matrix_client_element_container_labels_traefik_path_prefix ~ '/map_style.json') | regex_replace('^//', '/') }}`)
traefik.http.routers.matrix-client-element-map-style.service=matrix-client-element
traefik.http.routers.matrix-client-element-map-style.middlewares={{ (middlewares + ['matrix-client-element-map-style-add-headers']) | join(',') }}
traefik.http.routers.matrix-client-element-map-style.entrypoints={{ matrix_client_element_container_labels_traefik_entrypoints }}
traefik.http.routers.matrix-client-element-map-style.tls={{ matrix_client_element_container_labels_traefik_tls | to_json }}
{% if matrix_client_element_container_labels_traefik_tls %}
traefik.http.routers.matrix-client-element-map-style.tls.certResolver={{ matrix_client_element_container_labels_traefik_tls_certResolver }}
{% endif %}
{% endif %}
{% endif %}
{{ matrix_client_element_container_labels_additional_labels }}