Use a separate D-Bus server

README.md

@@ -49,7 +49,8 @@ SUSE is working on its next generation operating system called ALP (Adaptable Li
 
 ## Architecture
 
-This project is designed as a service-client system, using D-Bus for process communication.
+This project is designed as a service-client system, using a dedicated D-Bus server for process
+communication.
 
 ![Architecture](./doc/images/architecture.png)
 
@@ -109,8 +110,8 @@ $ sudo zypper in gcc gcc-c++ make openssl-devel ruby-devel augeas-devel npm cock
 * Setup the D-Installer services:
 
 ~~~
-$ sudo cp service/share/dbus.conf /usr/share/dbus-1/system.d/org.opensuse.DInstaller.conf
-$ cd service;
+$ sudo cp service/share/dbus.conf /usr/share/dbus-1/d-installer.conf
+$ cd service
 $ bundle config set --local path 'vendor/bundle';
 $ bundle install
 $ cd -

Rakefile

@@ -84,6 +84,8 @@ task package: [] do
   end
 end
 
+SERVICES_DIR = "/usr/share/dbus-1/d-installer-services"
+
 # support for patching by the yupdate script,
 # only when running in the inst-sys or live medium
 if File.exist?("/.packages.initrd") || `mount`.match?(/^[\w]+ on \/ type overlay/)
@@ -97,8 +99,9 @@ if File.exist?("/.packages.initrd") || `mount`.match?(/^[\w]+ on \/ type overlay
       sh "gem install --local --force --no-format-exec --no-doc --build-root #{destdir.shellescape} d-installer-*.gem"
 
       # update the DBus configuration files
-      sh "cp share/org.opensuse.DInstaller*.service /usr/share/dbus-1/system-services"
-      sh "cp share/dbus.conf /usr/share/dbus-1/system.d/org.opensuse.DInstaller.conf"
+      FileUtils.mkdir_p(SERVICES_DIR)
+      sh "cp share/org.opensuse.DInstaller*.service #{SERVICES_DIR}"
+      sh "cp share/dbus.conf /usr/share/dbus-1/d-installer.conf"
 
       # update the systemd service file
       source_file = "share/systemd.service"

service/bin/d-installer

@@ -33,6 +33,7 @@ Dir.chdir(__dir__) do
   require "bundler/setup"
 end
 require "dinstaller/dbus/service_runner"
+require "dinstaller/dbus/server_manager"
 
 # Set up a {Logger} suitable either for terminal (started manually)
 # or syslog (D-Bus activated)
@@ -80,6 +81,8 @@ def start_all_services
   end
 end
 
+dbus_server_manager = DInstaller::DBus::ServerManager.new
+
 if ARGV.empty?
   start_all_services
   Signal.trap("SIGINT") do
@@ -93,17 +96,25 @@ elsif ["-h", "--help"].include?(ARGV[0])
   puts "#{me} -h|--help"
   puts "#{me} -s|--status"
   puts "#{me} -k|--kill"
+  puts "#{me} -d|--daemon"
   puts "#{me} #{ORDERED_SERVICES.sort.join("|")}"
 elsif ["-s", "--status"].include?(ARGV[0])
   # The .[a-z] ensures matching the forked processes
   # which can be distinguished by having a non-option argument
   system "pgrep -fl bin/d-installer.[a-z]"
   # busctl is prettier but will find nothing until the service files are installed,
   # hence the pgrep above
-  system "busctl | grep -E '^NAME|DInstaller'"
+  system "busctl --address #{dbus_server_manager.address} | grep -E '^NAME|DInstaller'"
 elsif ["-k", "--kill"].include?(ARGV[0])
   system "pkill -f bin/d-installer.[a-z]"
+  # stop the d-bus daemon
+  dbus_server_manager.stop_server
+elsif ["-d", "--daemon"].include?(ARGV[0])
+  # start the D-Bus server
+  pid = dbus_server_manager.find_or_start_server
+  puts pid
 else
+  dbus_server_manager.find_or_start_server
   name = ARGV[0]
   Signal.trap("SIGINT") do
     puts "Stopping #{name} service..."

service/lib/dinstaller/dbus/bus.rb

@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+# Copyright (c) [2022] SUSE LLC
+#
+# All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of version 2 of the GNU General Public License as published
+# by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, contact SUSE LLC.
+#
+# To contact SUSE LLC about this file by physical or electronic mail, you may
+# find current contact information at www.suse.com.
+
+require "dbus"
+require "dinstaller/dbus/server_manager"
+
+module DInstaller
+  module DBus
+    # Represents the D-Installer bus, a distinct one from the system and session buses.
+    class Bus < ::DBus::Connection
+      class << self
+        # Returns the current D-Bus connection
+        #
+        # @return [Bus] D-Bus connection
+        def current
+          return @current if @current
+
+          dbus_manager = ServerManager.new
+          dbus_manager.find_or_start_server
+          @current = new(dbus_manager.address)
+        end
+
+        def reset
+          @current = nil
+        end
+      end
+
+      # @param address [String] a connectable address
+      # @see https://dbus.freedesktop.org/doc/dbus-specification.html#addresses
+      def initialize(address)
+        super(address)
+        send_hello
+      end
+    end
+  end
+end

service/lib/dinstaller/dbus/clients/base.rb

@@ -20,6 +20,7 @@
 # find current contact information at www.suse.com.
 
 require "dbus"
+require "dinstaller/dbus/bus"
 require "abstract_method"
 
 module DInstaller
@@ -63,7 +64,7 @@ def on_properties_change(dbus_object, &block)
         end
 
         def bus
-          @bus ||= ::DBus::SystemBus.instance
+          @bus ||= Bus.current
         end
       end
     end

service/lib/dinstaller/dbus/language_service.rb

@@ -20,6 +20,7 @@
 # find current contact information at www.suse.com.
 
 require "dbus"
+require "dinstaller/dbus/bus"
 require "dinstaller/dbus/language"
 require "dinstaller/language"
 
@@ -45,7 +46,7 @@ class LanguageService
       # @param logger [Logger]
       def initialize(_config, logger = nil)
         @logger = logger || Logger.new($stdout)
-        @bus = ::DBus::SystemBus.instance
+        @bus = Bus.current
       end
 
       # Exports the installer object through the D-Bus service

service/lib/dinstaller/dbus/manager_service.rb

@@ -22,6 +22,7 @@
 require "dbus"
 require "dinstaller/manager"
 require "dinstaller/cockpit_manager"
+require "dinstaller/dbus/bus"
 require "dinstaller/dbus/manager"
 require "dinstaller/dbus/storage/proposal"
 
@@ -54,7 +55,7 @@ def initialize(config, logger = nil)
         @config = config
         @manager = DInstaller::Manager.new(config, logger)
         @logger = logger || Logger.new($stdout)
-        @bus = ::DBus::SystemBus.instance
+        @bus = Bus.current
       end
 
       # Initializes and exports the D-Bus API

service/lib/dinstaller/dbus/questions_service.rb

@@ -20,6 +20,7 @@
 # find current contact information at www.suse.com.
 
 require "dbus"
+require "dinstaller/dbus/bus"
 require "dinstaller/dbus/questions"
 require "dinstaller/questions_manager"
 
@@ -42,7 +43,7 @@ class QuestionsService
       # @param logger [Logger]
       def initialize(_config, logger = nil)
         @logger = logger || Logger.new($stdout)
-        @bus = ::DBus::SystemBus.instance
+        @bus = Bus.current
         @backend ||= DInstaller::QuestionsManager.new(logger)
       end
 

service/lib/dinstaller/dbus/server_manager.rb

@@ -0,0 +1,135 @@
+# frozen_string_literal: true
+
+# Copyright (c) [2022] SUSE LLC
+#
+# All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of version 2 of the GNU General Public License as published
+# by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, contact SUSE LLC.
+#
+# To contact SUSE LLC about this file by physical or electronic mail, you may
+# find current contact information at www.suse.com.
+
+require "cheetah"
+require "fileutils"
+
+module DInstaller
+  module DBus
+    # This class takes care of setting up the D-Installer D-Bus server
+    #
+    # @example Find the current server or start a new if it is not running
+    #   manager = DBusManager.new
+    #   manager.find_or_start_server
+    class ServerManager
+      # @return [String] Default run directory path
+      DEFAULT_RUN_DIRECTORY = "/run/d-installer"
+      private_constant :DEFAULT_RUN_DIRECTORY
+
+      attr_reader :run_directory
+
+      def initialize(run_directory: DEFAULT_RUN_DIRECTORY)
+        @run_directory = run_directory
+      end
+
+      # Finds the current D-Bus server or starts a new one
+      #
+      # @return [Integer,nil] PID of the server process or nil if it
+      #   was not possible to start a new one
+      def find_or_start_server
+        find_server || start_server
+      end
+
+      # Starts a D-Bus server
+      #
+      # @return [Integer,nil] PID of the new server. Returns nil if it failed to start
+      #   the server.
+      def start_server
+        FileUtils.mkdir_p(run_directory)
+
+        output = Cheetah.run(
+          "/usr/bin/dbus-daemon",
+          "--config-file", config_file,
+          "--address", address,
+          "--fork", "--systemd-activation",
+          "--print-pid",
+          stdout: :capture
+        )
+        File.write(address_file, address)
+        pid = output.strip
+        File.write(pid_file, pid)
+        pid.to_i
+      rescue Cheetah::ExecutionFailed => e
+        puts "Could not start the DBus daemon: #{e.message}"
+        nil
+      end
+
+      # Gets the PID of the running server
+      #
+      # @return [Integer,nil] PID of the process if it exists, nil otherwise.
+      def find_server
+        return nil unless File.exist?(pid_file)
+
+        pid = File.read(pid_file).to_i
+        return nil if pid.zero?
+
+        begin
+          Process.getpgid(pid)
+          pid
+        rescue Errno::ESRCH # the process is not found
+          nil
+        end
+      end
+
+      # Stops the running server
+      def stop_server
+        pid = find_server
+        return unless pid
+
+        Process.kill("KILL", pid.to_i)
+      end
+
+      # Returns the D-Bus address
+      #
+      # @return [String]
+      def address
+        @address ||= "unix:path=#{File.join(run_directory, "bus")}"
+      end
+
+    private
+
+      # Returns the path to the configuration file
+      #
+      # It prefers a local configuration under `share/dbus.conf`. Otherwise, it falls back to a
+      # system-wide location.
+      def config_file
+        file = File.join(Dir.pwd, "share", "dbus.conf")
+        return file if File.exist?(file)
+
+        "/usr/share/dbus-1/d-installer.conf"
+      end
+
+      # Returns the path to the file containing the PID
+      #
+      # @return [String]
+      def pid_file
+        @pid_file ||= File.join(run_directory, "bus.pid")
+      end
+
+      # Returns the path to the file containing the D-Bus address
+      #
+      # @return [String]
+      def address_file
+        @address_file ||= File.join(run_directory, "bus.address")
+      end
+    end
+  end
+end

service/lib/dinstaller/dbus/software_service.rb

@@ -20,6 +20,7 @@
 # find current contact information at www.suse.com.
 
 require "dbus"
+require "dinstaller/dbus/bus"
 require "dinstaller/dbus/software"
 require "dinstaller/software"
 
@@ -42,7 +43,7 @@ class SoftwareService
       # @param logger [Logger]
       def initialize(config, logger = nil)
         @logger = logger || Logger.new($stdout)
-        @bus = ::DBus::SystemBus.instance
+        @bus = Bus.current
         @backend = DInstaller::Software::Manager.new(config, logger)
         @backend.on_progress_change { dispatch }
       end

service/lib/dinstaller/dbus/storage_service.rb

@@ -20,6 +20,7 @@
 # find current contact information at www.suse.com.
 
 require "dbus"
+require "dinstaller/dbus/bus"
 require "dinstaller/dbus/storage"
 require "dinstaller/storage"
 
@@ -42,7 +43,7 @@ class StorageService
       # @param logger [Logger]
       def initialize(config, logger = nil)
         @logger = logger || Logger.new($stdout)
-        @bus = ::DBus::SystemBus.instance
+        @bus = Bus.current
         @backend = DInstaller::Storage::Manager.new(config, logger)
         @backend.on_progress_change { dispatch }
       end

service/lib/dinstaller/dbus/users_service.rb

@@ -20,6 +20,7 @@
 # find current contact information at www.suse.com.
 
 require "dbus"
+require "dinstaller/dbus/bus"
 require "dinstaller/dbus/users"
 require "dinstaller/users"
 
@@ -45,7 +46,7 @@ class UsersService
       # @param logger [Logger]
       def initialize(_config, logger = nil)
         @logger = logger || Logger.new($stdout)
-        @bus = ::DBus::SystemBus.instance
+        @bus = Bus.current
       end
 
       # Exports the installer object through the D-Bus service