Add instructions to serve media on another domain

docs/configuration/hardening.md

@@ -62,6 +62,20 @@ An additional “Expect-CT” header will be sent with the configured `ct_max_ag
 
 If you click on a link, your browser’s request to the other site will include from where it is coming from. The “Referrer policy” header tells the browser how and if it should send this information. (see [Referrer policy](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referrer-Policy))
 
+### Uploaded media and media proxy
+
+It is STRONGLY RECOMMENDED to serve both the locally-uploaded media and the media proxy from another domain than the domain that Pleroma runs on, if applicable.
+
+```elixir
+config :pleroma, :media_proxy,
+  base_url: "https://some.other.domain"
+
+config :pleroma, Pleroma.Upload,
+  base_url: "https://some.other.domain"
+```
+
+See `installation/pleroma-mediaproxy.nginx` for examples on how to configure your media proxy.
+
 ## systemd
 
 A systemd unit example is provided at `installation/pleroma.service`.

installation/pleroma-mediaproxy.nginx

@@ -0,0 +1,97 @@
+# This file is for those who want to serve uploaded media and media proxy over
+# another domain. This is STRONGLY RECOMMENDED.
+# This is meant to be used ALONG WITH `pleroma.nginx`.
+
+# If this is a new instance, replace the `location ~ ^/(media|proxy)` section in
+# `pleroma.nginx` with the following to completely disable access to media from the main domain:
+# location ~ ^/(media|proxy) {
+#     return 404;
+# }
+#
+# If you are configuring an existing instance to use another domain
+# for media, you will want to keep redirecting all existing local media to the new domain
+# so already-uploaded media will not break.
+# Replace the `location ~ ^/(media|proxy)` section in `pleroma.nginx` with the following:
+#
+# location /media {
+#     return 301 https://some.other.domain$request_uri;
+# }
+#
+# location /proxy {
+#     return 404;
+# }
+
+server {
+    server_name    some.other.domain;
+
+    listen         80;
+    listen         [::]:80;
+
+    # Uncomment this if you need to use the 'webroot' method with certbot. Make sure
+    # that the directory exists and that it is accessible by the webserver. If you followed
+    # the guide, you already ran 'mkdir -p /var/lib/letsencrypt' to create the folder.
+    # You may need to load this file with the ssl server block commented out, run certbot
+    # to get the certificate, and then uncomment it.
+    #
+    # location ~ /\.well-known/acme-challenge {
+    #     root /var/lib/letsencrypt/;
+    # }
+    location / {
+      return         301 https://$server_name$request_uri;
+    }
+}
+
+server {
+    server_name some.other.domain;
+
+    listen 443 ssl http2;
+    listen [::]:443 ssl http2;
+    ssl_session_timeout 1d;
+    ssl_session_cache shared:MozSSL:10m;  # about 40000 sessions
+    ssl_session_tickets off;
+
+    ssl_trusted_certificate   /etc/letsencrypt/live/some.other.domain/chain.pem;
+    ssl_certificate           /etc/letsencrypt/live/some.other.domain/fullchain.pem;
+    ssl_certificate_key       /etc/letsencrypt/live/some.other.domain/privkey.pem;
+
+    ssl_protocols TLSv1.2 TLSv1.3;
+    ssl_ciphers "ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:!aNULL:!eNULL:!EXPORT:!DES:!MD5:!PSK:!RC4";
+    ssl_prefer_server_ciphers off;
+    # In case of an old server with an OpenSSL version of 1.0.2 or below,
+    # leave only prime256v1 or comment out the following line.
+    ssl_ecdh_curve X25519:prime256v1:secp384r1:secp521r1;
+    ssl_stapling on;
+    ssl_stapling_verify on;
+
+    gzip_vary on;
+    gzip_proxied any;
+    gzip_comp_level 6;
+    gzip_buffers 16 8k;
+    gzip_http_version 1.1;
+    gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript application/activity+json application/atom+xml;
+
+    # the nginx default is 1m, not enough for large media uploads
+    client_max_body_size 16m;
+    ignore_invalid_headers off;
+
+    proxy_http_version 1.1;
+    proxy_set_header Upgrade $http_upgrade;
+    proxy_set_header Connection "upgrade";
+    proxy_set_header Host $http_host;
+    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+
+    location / { return 404; }
+
+    location ~ ^/(media|proxy) {
+        proxy_cache        pleroma_media_cache;
+        slice              1m;
+        proxy_cache_key    $host$uri$is_args$args$slice_range;
+        proxy_set_header   Range $slice_range;
+        proxy_cache_valid  200 206 301 304 1h;
+        proxy_cache_lock   on;
+        proxy_ignore_client_abort on;
+        proxy_buffering    on;
+        chunked_transfer_encoding on;
+        proxy_pass         http://phoenix;
+    }
+}