Print console messages to $stderr if present

Using ConsoleHelper::write_stderr

lib/gitlab_access_status.rb

@@ -3,12 +3,14 @@ require 'json'
 class GitAccessStatus
   HTTP_MULTIPLE_CHOICES = '300'.freeze
 
-  attr_reader :message, :gl_repository, :gl_project_path, :gl_id, :gl_username, :gitaly, :git_protocol, :git_config_options, :payload
+  attr_reader :message, :gl_repository, :gl_project_path, :gl_id, :gl_username,
+              :gitaly, :git_protocol, :git_config_options, :payload,
+              :gl_console_messages
 
   def initialize(status, status_code, message, gl_repository: nil,
                  gl_project_path: nil, gl_id: nil,
                  gl_username: nil, gitaly: nil, git_protocol: nil,
-                 git_config_options: nil, payload: nil)
+                 git_config_options: nil, payload: nil, gl_console_messages: [])
     @status = status
     @status_code = status_code
     @message = message
@@ -20,6 +22,7 @@ class GitAccessStatus
     @gitaly = gitaly
     @git_protocol = git_protocol
     @payload = payload
+    @gl_console_messages = gl_console_messages
   end
 
   def self.create_from_json(json, status_code)
@@ -34,7 +37,8 @@ class GitAccessStatus
         git_config_options: values["git_config_options"],
         gitaly: values["gitaly"],
         git_protocol: values["git_protocol"],
-        payload: values["payload"])
+        payload: values["payload"],
+        gl_console_messages: values["gl_console_messages"])
   end
 
   def allowed?

lib/gitlab_shell.rb

@@ -66,6 +66,8 @@ class GitlabShell # rubocop:disable Metrics/ClassLength
       @username = access_status.gl_username
       @git_config_options = access_status.git_config_options
       @gl_id = access_status.gl_id if defined?(@who)
+
+      write_stderr(access_status.gl_console_messages)
     elsif !defined?(@gl_id)
       # We're processing an API command like 2fa_recovery_codes, but
       # don't have a @gl_id yet, that means we're in the "username"

spec/gitlab_shell_spec.rb

@@ -33,7 +33,8 @@ describe GitlabShell do
       gl_username: gl_username,
       git_config_options: git_config_options,
       gitaly: { 'repository' => { 'relative_path' => repo_name, 'storage_name' => 'default'} , 'address' => 'unix:gitaly.socket' },
-      git_protocol: git_protocol
+      git_protocol: git_protocol,
+      gl_console_messages:  gl_console_messages
     )
   end
 
@@ -69,6 +70,7 @@ describe GitlabShell do
   let(:gl_username) { 'testuser' }
   let(:git_config_options) { ['receive.MaxInputSize=10000'] }
   let(:git_protocol) { 'version=2' }
+  let(:gl_console_messages) { nil }
 
   before do
     allow_any_instance_of(GitlabConfig).to receive(:audit_usernames).and_return(false)
@@ -438,6 +440,19 @@ describe GitlabShell do
         end
       end
     end
+
+    context 'with a console message' do
+      let(:ssh_cmd) { "git-receive-pack gitlab-ci.git" }
+      let(:gl_console_messages) { 'Very important message' }
+
+      before do
+        allow(api).to receive(:check_access).and_return(gitaly_check_access)
+      end
+
+      it 'displays the message on $stderr' do
+        expect { subject.exec(ssh_cmd) }.to output("> GitLab: #{gl_console_messages}\n").to_stderr
+      end
+    end
   end
 
   describe '#validate_access' do