Deprecate support for using `HOST` environment to specify server IP (#32540)

At SuSE, `$HOST` is set by default and is equal to `$HOSTNAME`.
https://www.suse.com/documentation/sled11/book_sle_admin/data/sec_adm_variables.html

Therefore, by default, it binds to hostname instead of `localhost`.
This seems not to be appropriate as default behavior.

In order to avoid the name of the environment variable being used,
I changed the environment variable from `HOST` to `BINDING`.

Fixes #29516.

1 files changed, 12 insertions, 2 deletions

diff --git a/railties/lib/rails/commands/server/server_command.rb b/railties/lib/rails/commands/server/server_command.rb
index 6da300e356..77b6c1f65d 100644
--- a/railties/lib/rails/commands/server/server_command.rb
+++ b/railties/lib/rails/commands/server/server_command.rb
@@ -219,7 +219,7 @@ module Rails
                 user_supplied_options << name
               end
             end
-            user_supplied_options << :Host if ENV["HOST"]
+            user_supplied_options << :Host if ENV["HOST"] || ENV["BINDING"]
             user_supplied_options << :Port if ENV["PORT"]
             user_supplied_options.uniq
           end
@@ -234,7 +234,17 @@ module Rails
             options[:binding]
           else
             default_host = environment == "development" ? "localhost" : "0.0.0.0"
-            ENV.fetch("HOST", default_host)
+
+            if ENV["HOST"] && !ENV["BINDING"]
+              ActiveSupport::Deprecation.warn(<<-MSG.squish)
+                Using the `HOST` environment to specify the IP is deprecated and will be removed in Rails 6.1.
+                Please use `BINDING` environment instead.
+              MSG
+
+              return ENV["HOST"]
+            end
+
+            ENV.fetch("BINDING", default_host)
           end
         end