Ensure `authorized_keys_enabled` defaults to true

Locally, if Spring was not restarted, `current_application_settings` was still cached, which prevented the migration from editing the file. This will also ensure that any app server somehow hitting old cache data will properly default this setting regardless.

lib/gitlab/shell.rb

@@ -415,6 +415,8 @@ module Gitlab
     end
 
     def authorized_keys_enabled?
+      return true if current_application_settings.authorized_keys_enabled.nil?
+
       current_application_settings.authorized_keys_enabled
     end
   end

spec/lib/gitlab/shell_spec.rb

@@ -126,6 +126,21 @@ describe Gitlab::Shell, lib: true do
         gitlab_shell.add_key('key-123', 'ssh-rsa foobar trailing garbage')
       end
     end
+
+    context 'when authorized_keys_enabled is nil' do
+      before do
+        stub_application_setting(authorized_keys_enabled: nil)
+      end
+
+      it 'removes trailing garbage' do
+        allow(gitlab_shell).to receive(:gitlab_shell_keys_path).and_return(:gitlab_shell_keys_path)
+        expect(Gitlab::Utils).to receive(:system_silent).with(
+          [:gitlab_shell_keys_path, 'add-key', 'key-123', 'ssh-rsa foobar']
+        )
+
+        gitlab_shell.add_key('key-123', 'ssh-rsa foobar trailing garbage')
+      end
+    end
   end
 
   describe '#batch_add_keys' do
@@ -152,6 +167,20 @@ describe Gitlab::Shell, lib: true do
         end
       end
     end
+
+    context 'when authorized_keys_enabled is nil' do
+      before do
+        stub_application_setting(authorized_keys_enabled: nil)
+      end
+
+      it 'instantiates KeyAdder' do
+        expect_any_instance_of(Gitlab::Shell::KeyAdder).to receive(:add_key).with('key-123', 'ssh-rsa foobar')
+
+        gitlab_shell.batch_add_keys do |adder|
+          adder.add_key('key-123', 'ssh-rsa foobar')
+        end
+      end
+    end
   end
 
   describe '#remove_key' do
@@ -178,6 +207,21 @@ describe Gitlab::Shell, lib: true do
       end
     end
 
+    context 'when authorized_keys_enabled is nil' do
+      before do
+        stub_application_setting(authorized_keys_enabled: nil)
+      end
+
+      it 'removes trailing garbage' do
+        allow(gitlab_shell).to receive(:gitlab_shell_keys_path).and_return(:gitlab_shell_keys_path)
+        expect(Gitlab::Utils).to receive(:system_silent).with(
+          [:gitlab_shell_keys_path, 'rm-key', 'key-123', 'ssh-rsa foobar']
+        )
+
+        gitlab_shell.remove_key('key-123', 'ssh-rsa foobar')
+      end
+    end
+
     context 'when key content is not given' do
       it 'calls rm-key with only one argument' do
         allow(gitlab_shell).to receive(:gitlab_shell_keys_path).and_return(:gitlab_shell_keys_path)
@@ -211,6 +255,19 @@ describe Gitlab::Shell, lib: true do
         gitlab_shell.remove_all_keys
       end
     end
+
+    context 'when authorized_keys_enabled is nil' do
+      before do
+        stub_application_setting(authorized_keys_enabled: nil)
+      end
+
+      it 'removes trailing garbage' do
+        allow(gitlab_shell).to receive(:gitlab_shell_keys_path).and_return(:gitlab_shell_keys_path)
+        expect(Gitlab::Utils).to receive(:system_silent).with([:gitlab_shell_keys_path, 'clear'])
+
+        gitlab_shell.remove_all_keys
+      end
+    end
   end
 
   describe '#remove_keys_not_found_in_db' do