Add .deb file metadata extractor

app/services/packages/debian/extract_deb_metadata_service.rb

+# frozen_string_literal: true
+
+module Packages
+  module Debian
+    # Returns .deb file metadata
+    class ExtractDebMetadataService
+      CommandFailedError = Class.new(StandardError)
+
+      def initialize(file_path)
+        @file_path = file_path
+      end
+
+      def execute
+        unless success?
+          raise CommandFailedError, "The `#{cmd}` command failed (status: #{result.status}) with the following error:\n#{result.stderr}"
+        end
+
+        sections = ParseDebian822Service.new(result.stdout).execute
+
+        sections.each_value.first
+      end
+
+      private
+
+      def cmd
+        @cmd ||= begin
+          dpkg_deb_path = Gitlab.config.packages.dpkg_deb_path
+          [dpkg_deb_path, '--field', @file_path]
+        end
+      end
+
+      def result
+        @result ||= Gitlab::Popen.popen_with_detail(cmd)
+      end
+
+      def success?
+        result.status&.exitstatus == 0
+      end
+    end
+  end
+end

changelogs/unreleased/debian_parsers.yml

+---
+title: Debian RFC822 and .deb metadata extractor
+merge_request: 44029
+author: Mathieu Parent
+type: added

config/gitlab.yml.example

@@ -317,6 +317,7 @@ production: &base
   ## Packages (maven repository, npm registry, etc...)
   packages:
     enabled: true
+    dpkg_deb_path: /usr/bin/dpkg-deb
     # The location where build packages are stored (default: shared/packages).
     # storage_path: shared/packages
     object_store:

config/initializers/1_settings.rb

@@ -354,9 +354,10 @@
 # Packages
 #
 Settings['packages'] ||= Settingslogic.new({})
-Settings.packages['enabled']      = true if Settings.packages['enabled'].nil?
-Settings.packages['storage_path'] = Settings.absolute(Settings.packages['storage_path'] || File.join(Settings.shared['path'], "packages"))
-Settings.packages['object_store'] = ObjectStoreSettings.legacy_parse(Settings.packages['object_store'])
+Settings.packages['enabled']       = true if Settings.packages['enabled'].nil?
+Settings.packages['dpkg_deb_path'] = '/usr/bin/dpkg-deb' if Settings.packages['dpkg_deb_path'].nil?
+Settings.packages['storage_path']  = Settings.absolute(Settings.packages['storage_path'] || File.join(Settings.shared['path'], "packages"))
+Settings.packages['object_store']  = ObjectStoreSettings.legacy_parse(Settings.packages['object_store'])
 
 #
 # Dependency Proxy

spec/services/packages/debian/extract_deb_metadata_service_spec.rb

+# frozen_string_literal: true
+require 'spec_helper'
+
+RSpec.describe Packages::Debian::ExtractDebMetadataService do
+  subject { described_class.new(file_path) }
+
+  let(:file_name) { 'libsample0_1.2.3~alpha2_amd64.deb' }
+  let(:file_path) { "spec/fixtures/packages/debian/#{file_name}" }
+
+  context 'with correct file' do
+    it 'return as expected' do
+      expected = {
+        'Package': 'libsample0',
+        'Source': 'sample',
+        'Version': '1.2.3~alpha2',
+        'Architecture': 'amd64',
+        'Maintainer': 'John Doe <john.doe@example.com>',
+        'Installed-Size': '7',
+        'Section': 'libs',
+        'Priority': 'optional',
+        'Multi-Arch': 'same',
+        'Homepage': 'https://gitlab.com/',
+        'Description': "Some mostly empty lib\nUsed in GitLab tests.\n\nTesting another paragraph."
+      }
+
+      expect(subject.execute).to eq expected
+    end
+  end
+
+  context 'with incorrect file' do
+    let(:file_name) { 'README.md' }
+
+    it 'raise error' do
+      expect {subject.execute}.to raise_error(described_class::CommandFailedError, /is not a Debian format archive/i)
+    end
+  end
+end