Allow custom user and port for builder host

lib/kamal/cli/build.rb

@@ -114,8 +114,11 @@ def verify_local_dependencies
     def connect_to_remote_host(remote_host)
       remote_uri = URI.parse(remote_host)
       if remote_uri.scheme == "ssh"
-        options = { user: remote_uri.user, port: remote_uri.port }.compact
-        on(remote_uri.host, options) do
+        host = SSHKit::Host.new(
+          hostname: remote_uri.host,
+          ssh_options: { user: remote_uri.user, port: remote_uri.port }.compact
+        )
+        on(host, options) do
           execute "true"
         end
       end

test/cli/build_test.rb

@@ -79,6 +79,14 @@ class CliBuildTest < CliTestCase
     end
   end
 
+  test "create remote with custom ports" do
+    run_command("create", fixture: :with_remote_builder_and_custom_ports).tap do |output|
+      assert_match "Running /usr/bin/env true on 1.1.1.5", output
+      assert_match "docker context create kamal-app-native-remote-amd64 --description 'kamal-app-native-remote amd64 native host' --docker 'host=ssh://app@1.1.1.5:2122'", output
+      assert_match "docker buildx create --name kamal-app-native-remote kamal-app-native-remote-amd64 --platform linux/amd64", output
+    end
+  end
+
   test "create with error" do
     stub_setup
     SSHKit::Backend::Abstract.any_instance.stubs(:execute)

test/fixtures/deploy_with_remote_builder_and_custom_ports.yml

@@ -0,0 +1,45 @@
+service: app
+image: dhh/app
+servers:
+  web:
+    - "1.1.1.1"
+    - "1.1.1.2"
+  workers:
+    - "1.1.1.3"
+    - "1.1.1.4"
+registry:
+  username: user
+  password: pw
+
+accessories:
+  mysql:
+    image: mysql:5.7
+    host: 1.1.1.3
+    port: 3306
+    env:
+      clear:
+        MYSQL_ROOT_HOST: '%'
+      secret:
+        - MYSQL_ROOT_PASSWORD
+    files:
+      - test/fixtures/files/my.cnf:/etc/mysql/my.cnf
+    directories:
+      - data:/var/lib/mysql
+  redis:
+    image: redis:latest
+    roles:
+      - web
+    port: 6379
+    directories:
+      - data:/data
+
+readiness_delay: 0
+
+ssh:
+  user: root
+  port: 22
+
+builder:
+  remote:
+    arch: amd64
+    host: ssh://app@1.1.1.5:2122