Add 'hsts' as config option

src/invidious.cr

@@ -193,7 +193,7 @@ before_all do |env|
   env.response.headers["Content-Security-Policy"] = "default-src blob: data: 'self' #{host_url} 'unsafe-inline' 'unsafe-eval'; media-src blob: 'self' #{host_url} https://*.googlevideo.com:443"
   env.response.headers["Referrer-Policy"] = "same-origin"
 
-  if Kemal.config.ssl || config.https_only
+  if (Kemal.config.ssl || config.https_only) && config.hsts
     env.response.headers["Strict-Transport-Security"] = "max-age=31536000; includeSubDomains; preload"
   end
 
@@ -5355,7 +5355,9 @@ if Kemal.config.ssl
         redirect_url += "?#{env.request.query}"
       end
 
-      env.response.headers["Strict-Transport-Security"] = "max-age=31536000; includeSubDomains; preload"
+      if config.hsts
+        env.response.headers["Strict-Transport-Security"] = "max-age=31536000; includeSubDomains; preload"
+      end
       env.response.headers["Location"] = redirect_url
       env.response.status_code = 301
     end

src/invidious/helpers/helpers.cr

@@ -128,6 +128,7 @@ user: String,
     check_tables:      {type: Bool, default: false},                 # Check table integrity, automatically try to add any missing columns, create tables, etc.
     cache_annotations: {type: Bool, default: false},                 # Cache annotations requested from IA, will not cache empty annotations or annotations that only contain cards
     banner:            {type: String?, default: nil},                # Optional banner to be displayed along top of page for announcements, etc.
+    hsts:              {type: Bool?, default: true},                 # Enables 'Strict-Transport-Security'. Ensure that `domain` and all subdomains are served securely
   })
 end