Add build args

README.md

@@ -146,6 +146,28 @@ builder:
   multiarch: false
 ```
 
+### Configuring build args for new images
+
+Some images might need an argument passed in during build time, like a GITHUB_TOKEN to give access to private gem repositories. This can be done like so:
+
+```yaml
+builder:
+  args:
+    GITHUB_TOKEN: <create-a-new-token-from-github>
+```
+
+This build arg can then be used in the Dockerfile:
+
+```
+# Private repositories need an access token during the build
+ARG GITHUB_TOKEN
+ENV BUNDLE_GITHUB__COM=x-access-token:$GITHUB_TOKEN
+
+# Install application gems
+COPY Gemfile Gemfile.lock ./
+RUN bundle install
+```
+
 ## Commands
 
 ### Remote execution

lib/mrsk/commands/builder.rb

@@ -10,14 +10,12 @@ class Mrsk::Commands::Builder < Mrsk::Commands::Base
 
   def target
     case
-    when config.builder.nil?
+    when config.builder && config.builder["multiarch"] == false
-      multiarch
-    when config.builder["multiarch"] == false
       native
-    when config.builder["local"] && config.builder["remote"]
+    when config.builder && config.builder["local"] && config.builder["remote"]
       multiarch_remote
     else
-      raise ArgumentError, "Builder configuration incorrect: #{config.builder.inspect}"
+      multiarch
     end
   end
 

lib/mrsk/commands/builder/base.rb

@@ -0,0 +1,18 @@
+require "mrsk/commands/base"
+
+class Mrsk::Commands::Builder::Base < Mrsk::Commands::Base
+  delegate :argumentize, to: Mrsk::Configuration
+
+  def pull
+    docker :pull, config.absolute_image
+  end
+
+  def build_args
+    argumentize "--build-args", args
+  end
+
+  private
+    def args
+      config.builder["args"] || {}
+    end
+end

lib/mrsk/commands/builder/multiarch.rb

@@ -1,6 +1,6 @@
-require "mrsk/commands/base"
+require "mrsk/commands/builder/base"
 
-class Mrsk::Commands::Builder::Multiarch < Mrsk::Commands::Base
+class Mrsk::Commands::Builder::Multiarch < Mrsk::Commands::Builder::Base
   def create
     docker :buildx, :create, "--use", "--name", builder_name
   end
@@ -10,11 +10,7 @@ class Mrsk::Commands::Builder::Multiarch < Mrsk::Commands::Base
   end
 
   def push
-    docker :buildx, :build, "--push", "--platform linux/amd64,linux/arm64", "-t", config.absolute_image, "."
+    docker :buildx, :build, "--push", "--platform linux/amd64,linux/arm64", "-t", config.absolute_image, *build_args, "."
-  end
-
-  def pull
-    docker :pull, config.absolute_image
   end
 
   def info

lib/mrsk/commands/builder/native.rb

@@ -1,6 +1,6 @@
-require "mrsk/commands/base"
+require "mrsk/commands/builder/base"
 
-class Mrsk::Commands::Builder::Native < Mrsk::Commands::Base
+class Mrsk::Commands::Builder::Native < Mrsk::Commands::Builder::Base
   def create
     # No-op on native
   end
@@ -11,14 +11,10 @@ class Mrsk::Commands::Builder::Native < Mrsk::Commands::Base
 
   def push
     combine \
-      docker(:build, "-t", config.absolute_image, "."),
+      docker(:build, "-t", *build_args, config.absolute_image, "."),
       docker(:push, config.absolute_image)
   end
 
-  def pull
-    docker :pull, config.absolute_image
-  end
-
   def info
     # No-op on native
   end

test/builder_command_test.rb

@@ -21,4 +21,19 @@ class BuilderCommandTest < ActiveSupport::TestCase
     builder = Mrsk::Commands::Builder.new(Mrsk::Configuration.new(@config.merge({ builder: { "local" => { }, "remote" => { } } })))
     assert builder.remote?
   end
+
+  test "build args" do
+    builder = Mrsk::Commands::Builder.new(Mrsk::Configuration.new(@config.merge({ builder: { "args" => { "a" => 1, "b" => 2 } } })))
+    assert_equal [ "--build-args", "a=1", "--build-args", "b=2" ], builder.target.build_args
+  end
+
+  test "native push with build args" do
+    builder = Mrsk::Commands::Builder.new(Mrsk::Configuration.new(@config.merge({ builder: { "multiarch" => false, "args" => { "a" => 1, "b" => 2 } } })))
+    assert_equal [ :docker, :build, "-t", "--build-args", "a=1", "--build-args", "b=2", "dhh/app:123", ".", "&&", :docker, :push, "dhh/app:123" ], builder.push
+  end
+
+  test "multiarch push with build args" do
+    builder = Mrsk::Commands::Builder.new(Mrsk::Configuration.new(@config.merge({ builder: { "args" => { "a" => 1, "b" => 2 } } })))
+    assert_equal [ :docker, :buildx, :build, "--push", "--platform linux/amd64,linux/arm64", "-t", "dhh/app:123", "--build-args", "a=1", "--build-args", "b=2", "." ], builder.push
+  end
 end