Ask for proxy URL if proxy enabled.

Also change the true/false question to y/n

lib/mix/tasks/generate_config.ex

@@ -8,12 +8,20 @@ def run(_) do
     domain = IO.gets("What is your domain name? (e.g. pleroma.soykaf.com): ") |> String.trim
     name = IO.gets("What is the name of your instance? (e.g. Pleroma/Soykaf): ") |> String.trim
     email = IO.gets("What's your admin email address: ") |> String.trim
-    mediaproxy = IO.gets("Do you want to activate the mediaproxy? (true/false): ") |> String.trim
+    mediaproxy = IO.gets("Do you want to activate the mediaproxy? (y/N): ")
+    |> String.trim()
+    |> String.downcase()
+    |> String.starts_with?("y")
+    proxy_url = if mediaproxy do
+      IO.gets("What is the mediaproxy's URL? (e.g. https://cache.example.com): ") |> String.trim
+    else
+      "https://cache.example.com"
+    end
     secret =  :crypto.strong_rand_bytes(64) |> Base.encode64 |> binary_part(0, 64)
     dbpass =  :crypto.strong_rand_bytes(64) |> Base.encode64 |> binary_part(0, 64)
 
     resultSql = EEx.eval_file("lib/mix/tasks/sample_psql.eex", [dbpass: dbpass])
-    result = EEx.eval_file("lib/mix/tasks/sample_config.eex", [domain: domain, email: email, name: name, secret: secret, mediaproxy: mediaproxy, dbpass: dbpass])
+    result = EEx.eval_file("lib/mix/tasks/sample_config.eex", [domain: domain, email: email, name: name, secret: secret, mediaproxy: mediaproxy, proxy_url: proxy_url, dbpass: dbpass])
 
     IO.puts("\nWriting config to config/generated_config.exs.\n\nCheck it and configure your database, then copy it to either config/dev.secret.exs or config/prod.secret.exs")
     File.write("config/generated_config.exs", result)

lib/mix/tasks/sample_config.eex

@@ -13,7 +13,7 @@ config :pleroma, :instance,
 config :pleroma, :media_proxy,
   enabled: <%= mediaproxy %>,
   redirect_on_failure: true,
-  #base_url: "https://cache.pleroma.social"
+  base_url: "<%= proxy_url %>"
 
 # Configure your database
 config :pleroma, Pleroma.Repo,