reverse_proxy,endpoint,uploaded_media: add immutable cache-control flag

lib/pleroma/reverse_proxy.ex

@@ -12,7 +12,7 @@ defmodule Pleroma.ReverseProxy do
   @keep_resp_headers @resp_cache_headers ++
                        ~w(content-length content-type content-disposition content-encoding) ++
                        ~w(content-range accept-ranges vary)
-  @default_cache_control_header "public, max-age=1209600"
+  @default_cache_control_header "public, max-age=1209600, immutable"
   @valid_resp_codes [200, 206, 304]
   @max_read_duration :timer.seconds(30)
   @max_body_length :infinity

lib/pleroma/web/endpoint.ex

@@ -46,7 +46,7 @@ defmodule Pleroma.Web.Endpoint do
   plug(Pleroma.Web.Plugs.HTTPSecurityPlug)
   plug(Pleroma.Web.Plugs.UploadedMedia)
 
-  @static_cache_control "public, max-age=1209600"
+  @static_cache_control "public, max-age=1209600, immutable"
   @static_cache_disabled "public, no-cache"
 
   # InstanceStatic needs to be before Plug.Static to be able to override shipped-static files

lib/pleroma/web/plugs/uploaded_media.ex

@@ -17,7 +17,7 @@ defmodule Pleroma.Web.Plugs.UploadedMedia do
   # no slashes
   @path "media"
 
-  @default_cache_control_header "public, max-age=1209600"
+  @default_cache_control_header "public, max-age=1209600, immutable"
 
   def init(_opts) do
     static_plug_opts =