Richard Zink
f55d96f462
Direct fetching from a.basemaps.cartocdn.com was returning stripped/missing CORS headers in the user's browser, blocking the img.src load. Even with cache-busters the failure persisted. Solution: local nginx proxy at /carto/ that forwards to the upstream and always adds Access-Control-Allow-Origin: *. Key detail: the 'resolver' directive is required inside the proxy_pass location block so nginx can resolve the upstream hostname. Without it, the location block silently fails (the '/' location falls through to try_files ... =404, and the ~*\.(png|jpg)$ regex also matches and silently fails for GETs). Also added 'location ^~ /carto/' to give prefix matching strict priority over the .png regex match that was stealing the request. JS now uses /carto/voyager/ (relative URL through the same origin) so CORS preflight is not even needed.
38 lines
1.4 KiB
Plaintext
38 lines
1.4 KiB
Plaintext
server {
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listen 58881 default_server;
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server_name localhost _;
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root /usr/share/nginx/html;
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index background.html;
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location / {
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try_files $uri $uri/ =404;
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}
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# CORS proxy for map tiles. Forwards to the upstream tile server
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# but injects permissive CORS headers so the browser can load
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# tiles via cross-origin img.src requests. The 'resolver' is
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# required by the proxy module to resolve the upstream hostname.
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location ^~ /carto/ {
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resolver 1.1.1.1 8.8.8.8 ipv6=off valid=300s;
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proxy_pass https://a.basemaps.cartocdn.com/;
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proxy_ssl_server_name on;
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proxy_set_header Host a.basemaps.cartocdn.com;
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proxy_set_header User-Agent "Mozilla/5.0 (compatible; tile-proxy)";
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add_header Access-Control-Allow-Origin "*" always;
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add_header Access-Control-Allow-Methods "GET, HEAD, OPTIONS" always;
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add_header Access-Control-Max-Age 86400 always;
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}
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# CORS preflight handler
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location ~* \.(png|jpg)$ {
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if ($request_method = 'OPTIONS') {
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add_header Access-Control-Allow-Origin "*" always;
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add_header Access-Control-Allow-Methods "GET, HEAD, OPTIONS" always;
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add_header Access-Control-Max-Age 86400 always;
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add_header Content-Length 0;
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return 204;
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}
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add_header Access-Control-Allow-Origin "*" always;
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}
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}
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