Merge pull request #92 from testcontainers/feature/78-local-image-fallback

Support locally built images with Docker::Image.get  before pull

Author: guilleiguaran

core/lib/testcontainers/docker_container.rb

@@ -487,7 +487,18 @@ def start
 
       connection = Docker::Connection.new(Docker.url, Docker.options)
 
-      Docker::Image.create({"fromImage" => @image}.merge(@image_create_options), connection)
+      image_options = {"fromImage" => @image}.merge(@image_create_options)
+      image_reference = (image_options["fromImage"] || image_options[:fromImage] || @image).to_s
+      tag_option = image_options["tag"] || image_options[:tag]
+      if tag_option && !image_reference.end_with?(":#{tag_option}")
+        image_reference = "#{image_reference}:#{tag_option}"
+      end
+
+      begin
+        Docker::Image.get(image_reference, {}, connection)
+      rescue Docker::Error::NotFoundError
+        Docker::Image.create(image_options, connection)
+      end
 
       @_container ||= Docker::Container.create(_container_create_options)
       @_container.start

core/test/docker_container_test.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 require "test_helper"
+require "tmpdir"
+require "securerandom"
 
 class DockerContainerTest < TestcontainersTest
   def before_all
@@ -44,6 +46,38 @@ def test_it_creates_an_image_with_options
     bad_container.remove if bad_container.exists?
   end
 
+  def test_it_uses_locally_built_image_before_pulling
+    image_repo = "testcontainers-local-#{SecureRandom.hex(6)}"
+    image_tag = "latest"
+    image_reference = "#{image_repo}:#{image_tag}"
+    container = nil
+
+    Dir.mktmpdir do |dir|
+      dockerfile_path = File.join(dir, "Dockerfile")
+      File.write(dockerfile_path, <<~DOCKERFILE)
+        FROM alpine:latest
+        CMD ["sleep", "60"]
+      DOCKERFILE
+
+      Docker::Image.build_from_dir(dir, {"t" => image_reference, "dockerfile" => "Dockerfile"})
+    end
+
+    container = Testcontainers::DockerContainer.new(image_reference)
+    container.start
+
+    assert container.running?
+  ensure
+    if container
+      container.stop if container.running?
+      container.remove if container.exists?
+    end
+    begin
+      Docker::Image.get(image_reference).remove(force: true)
+    rescue Docker::Error::NotFoundError
+      # image already removed
+    end
+  end
+
   def test_it_returns_the_container_image
     assert_equal "hello-world", @container.image
   end