Add option for remote building of single-arch

README.md

@@ -164,6 +164,21 @@ Note: You must have Docker running on the remote host being used as a builder.
 
 With that configuration in place, you can setup the local/remote configuration using `mrsk build create`. If you wish to remove the contexts and buildx instances again, you can run `mrsk build remove`. If you had already built using the standard emulation setup, run `mrsk build remove` before doing `mrsk build remote`.
 
+### Configuring remote builder for single-arch
+
+If you're developing on ARM64 (like Apple Silicon), want to deploy on AMD64 (x86 64-bit), but don't need to run the image locally (or on other ARM64 hosts), you can configure a remote builder that just targets AMD64. This is a bit faster than building with multi-arch, as there's nothing to build locally.
+
+```yaml
+builder:
+  remote:
+    arch: amd64
+    host: ssh://root@192.168.0.1
+```
+
+Note: You must have Docker running on the remote host being used as a builder.
+
+With that configuration in place, you can setup the remote configuration using `mrsk build create`. If you wish to remove the contexts and buildx instances again, you can run `mrsk build remove`. If you had already built using the standard emulation setup, run `mrsk build remove` before doing `mrsk build remote`.
+
 ### Configuring native builder when multi-arch isn't needed
 
 If you're developing on the same architecture as the one you're deploying on, you can speed up the build a lot by forgoing a multi-arch image. This can be done by configuring the builder like so:

lib/mrsk/commands/builder.rb

@@ -2,10 +2,9 @@ require "mrsk/commands/base"
 
 class Mrsk::Commands::Builder < Mrsk::Commands::Base
   delegate :create, :remove, :push, :pull, :info, to: :target
-  delegate :native?, :multiarch?, :remote?, to: :name
 
   def name
-    target.class.to_s.demodulize.downcase.inquiry
+    target.class.to_s.remove("Mrsk::Commands::Builder::").underscore
   end
 
   def target
@@ -14,6 +13,8 @@ class Mrsk::Commands::Builder < Mrsk::Commands::Base
       native
     when config.builder && config.builder["local"] && config.builder["remote"]
       multiarch_remote
+    when config.builder && config.builder["remote"]
+      native_remote
     else
       multiarch
     end
@@ -23,6 +24,10 @@ class Mrsk::Commands::Builder < Mrsk::Commands::Base
     @native ||= Mrsk::Commands::Builder::Native.new(config)
   end
 
+  def native_remote
+    @native ||= Mrsk::Commands::Builder::Native::Remote.new(config)
+  end
+
   def multiarch
     @multiarch ||= Mrsk::Commands::Builder::Multiarch.new(config)
   end
@@ -33,5 +38,6 @@ class Mrsk::Commands::Builder < Mrsk::Commands::Base
 end
 
 require "mrsk/commands/builder/native"
+require "mrsk/commands/builder/native/remote"
 require "mrsk/commands/builder/multiarch"
 require "mrsk/commands/builder/multiarch/remote"

lib/mrsk/commands/builder/native/remote.rb

@@ -0,0 +1,71 @@
+require "mrsk/commands/builder/native"
+
+class Mrsk::Commands::Builder::Native::Remote < Mrsk::Commands::Builder::Native
+  def create
+    combine \
+      create_context,
+      create_buildx
+  end
+
+  def remove
+    combine \
+      remove_context,
+      remove_buildx
+  end
+
+  def push
+    docker :buildx, :build,
+      "--push",
+      "--platform", platform,
+      "-t", config.absolute_image,
+      *build_args,
+      *build_secrets,
+      "."
+  end
+
+  def info
+    combine \
+      docker(:context, :ls),
+      docker(:buildx, :ls)
+  end
+
+
+  private
+    def arch
+      config.builder["remote"]["arch"]
+    end
+
+    def host
+      config.builder["remote"]["host"]
+    end
+
+    def builder_name
+      "mrsk-#{config.service}"
+    end
+
+    def builder_name_with_arch
+      "#{builder_name}-#{arch}"
+    end
+
+    def platform
+      "linux/#{arch}"
+    end
+
+    def create_context
+      docker :context, :create,
+        builder_name_with_arch, "--description", "'#{builder_name} #{arch} native host'", "--docker", "'host=#{host}'"
+    end
+
+    def remove_context
+      docker :context, :rm, builder_name_with_arch
+    end
+
+    def create_buildx
+      docker :buildx, :create,
+        "--use", "--name", builder_name, builder_name_with_arch, "--platform", platform
+    end
+
+    def remove_buildx
+      docker :buildx, :rm, builder_name
+    end
+end

test/commands/builder_test.rb

@@ -8,15 +8,27 @@ class CommandsBuilderTest < ActiveSupport::TestCase
   end
 
   test "target multiarch by default" do
-    assert new_builder_command.multiarch?
+    builder = new_builder_command
+    assert_equal "multiarch", builder.name
+    assert_equal [:docker, :buildx, :build, "--push", "--platform linux/amd64,linux/arm64", "-t", "dhh/app:123", "."], builder.push
   end
 
   test "target native when multiarch is off" do
-    assert new_builder_command(builder: { "multiarch" => false }).native?
+    builder = new_builder_command(builder: { "multiarch" => false })
+    assert_equal "native", builder.name
+    assert_equal [:docker, :build, "-t", "dhh/app:123", ".", "&&", :docker, :push, "dhh/app:123"], builder.push
   end
 
   test "target multiarch remote when local and remote is set" do
-    assert new_builder_command(builder: { "local" => { }, "remote" => { } }).remote?
+    builder = new_builder_command(builder: { "local" => { }, "remote" => { } })
+    assert_equal "multiarch/remote", builder.name
+    assert_equal [:docker, :buildx, :build, "--push", "--platform linux/amd64,linux/arm64", "-t", "dhh/app:123", "."], builder.push
+  end
+
+  test "target native remote when only remote is set" do
+    builder = new_builder_command(builder: { "remote" => { "arch" => "amd64" } })
+    assert_equal "native/remote", builder.name
+    assert_equal [:docker, :buildx, :build, "--push", "--platform", "linux/amd64", "-t", "dhh/app:123", "."], builder.push
   end
 
   test "build args" do