Supports Passing SSH Agent Socket to Build Options

lib/kamal/commands/builder/base.rb

@@ -3,7 +3,7 @@ class Kamal::Commands::Builder::Base < Kamal::Commands::Base
   class BuilderError < StandardError; end
 
   delegate :argumentize, to: Kamal::Utils
-  delegate :args, :secrets, :dockerfile, :local_arch, :local_host, :remote_arch, :remote_host, :cache_from, :cache_to, to: :builder_config
+  delegate :args, :secrets, :dockerfile, :local_arch, :local_host, :remote_arch, :remote_host, :cache_from, :cache_to, :ssh_agent_socket?, to: :builder_config
 
   def clean
     docker :image, :rm, "--force", config.absolute_image
@@ -14,7 +14,7 @@ def pull
   end
 
   def build_options
-    [ *build_tags, *build_cache, *build_labels, *build_args, *build_secrets, *build_dockerfile ]
+    [ *build_tags, *build_cache, *build_labels, *build_args, *build_secrets, *build_dockerfile, *build_ssh_agent_socket ]
   end
 
   def build_context
@@ -54,6 +54,12 @@ def build_dockerfile
       end
     end
 
+    def build_ssh_agent_socket
+      if ssh_agent_socket?
+        [ "--ssh", "default=$SSH_AUTH_SOCK" ]
+      end
+    end
+
     def builder_config
       config.builder
     end

lib/kamal/configuration/builder.rb

@@ -81,6 +81,10 @@ def cache_to
     end
   end
 
+  def ssh_agent_socket?
+    @options["ssh_agent_socket"] == true
+  end
+
   private
     def valid?
       if @options["cache"] && @options["cache"]["type"]

test/commands/builder_test.rb

@@ -103,6 +103,14 @@ class CommandsBuilderTest < ActiveSupport::TestCase
       builder.push.join(" ")
   end
 
+  test "build with ssh agent socket" do
+    builder = new_builder_command(builder: { "ssh_agent_socket" => true })
+
+    assert_equal \
+      "-t dhh/app:123 -t dhh/app:latest --label service=\"app\" --file Dockerfile --ssh default=$SSH_AUTH_SOCK",
+      builder.target.build_options.join(" ")
+  end
+
   private
     def new_builder_command(additional_config = {})
       Kamal::Commands::Builder.new(Kamal::Configuration.new(@config.merge(additional_config), version: "123"))

test/configuration/builder_test.rb

@@ -148,4 +148,16 @@ class ConfigurationBuilderTest < ActiveSupport::TestCase
 
     assert_equal "..", @config_with_builder_option.builder.context
   end
+
+  test "ssh_agent_socket?" do
+    assert_not @config.builder.ssh_agent_socket?
+  end
+
+  test "setting ssh_agent_socket" do
+    @deploy_with_builder_option[:builder] = { "ssh_agent_socket" => true }
+
+    assert @config_with_builder_option.builder.ssh_agent_socket?
+    assert_equal "type=registry,ref=dhh/app-build-cache", @config_with_builder_option.builder.cache_from
+    # assert_equal "type=registry,mode=max,image-manifest=true,oci-mediatypes=true,ref=dhh/app-build-cache", @config_with_builder_option.builder.cache_to
+  end
 end