Generate permissive or restrictive robots.txt in the config generator

lib/mix/tasks/pleroma/instance.ex

@@ -81,6 +81,14 @@ def run(["gen" | rest]) do
 
       email = Common.get_option(options, :admin_email, "What is your admin email address?")
 
+      indexable =
+        Common.get_option(
+          options,
+          :indexable,
+          "Do you want search engines to index your site? (y/n)",
+          "y"
+        ) === "y"
+
       dbhost =
         Common.get_option(options, :dbhost, "What is the hostname of your database?", "localhost")
 
@@ -142,6 +150,8 @@ def run(["gen" | rest]) do
       Mix.shell().info("Writing #{psql_path}.")
       File.write(psql_path, result_psql)
 
+      write_robots_txt(indexable)
+
       Mix.shell().info(
         "\n" <>
           """
@@ -163,4 +173,28 @@ def run(["gen" | rest]) do
       )
     end
   end
+
+  defp write_robots_txt(indexable) do
+    robots_txt =
+      EEx.eval_file(
+        Path.expand("robots_txt.eex", __DIR__),
+        indexable: indexable
+      )
+
+    static_dir = Pleroma.Config.get([:instance, :static_dir], "instance/static/")
+
+    unless File.exists?(static_dir) do
+      File.mkdir_p!(static_dir)
+    end
+
+    robots_txt_path = Path.join(static_dir, "robots.txt")
+
+    if File.exists?(robots_txt_path) do
+      File.cp!(robots_txt_path, "#{robots_txt_path}.bak")
+      Mix.shell().info("Backing up existing robots.txt to #{robots_txt_path}.bak")
+    end
+
+    File.write(robots_txt_path, robots_txt)
+    Mix.shell().info("Writing #{robots_txt_path}.")
+  end
 end

lib/mix/tasks/pleroma/robots_txt.eex

@@ -0,0 +1,2 @@
+User-Agent: *
+Disallow: <%= if indexable, do: "", else: "/" %>