use Gemfile

.dockerignore

@@ -0,0 +1,3 @@
+spec
+fixtures
+screenshots

Dockerfile

@@ -1,7 +1,8 @@
 FROM ruby:2.6.3-alpine
 
-RUN gem install octokit
-
+WORKDIR /action
+COPY Gemfile Gemfile.lock /action/
+RUN bundle install
 COPY lib /action/lib
 
 CMD ["ruby", "/action/lib/index.rb"]

Gemfile

@@ -0,0 +1,2 @@
+source 'https://rubygems.org'
+gem 'octokit'

Gemfile.lock

@@ -0,0 +1,22 @@
+GEM
+  specs:
+    addressable (2.7.0)
+      public_suffix (>= 2.0.2, < 5.0)
+    faraday (0.17.0)
+      multipart-post (>= 1.2, < 3)
+    multipart-post (2.1.1)
+    octokit (4.14.0)
+      sawyer (~> 0.8.0, >= 0.5.3)
+    public_suffix (4.0.1)
+    sawyer (0.8.2)
+      addressable (>= 2.3.5)
+      faraday (> 0.8, < 2.0)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  octokit
+
+BUNDLED WITH
+   1.17.2

lib/index.rb

@@ -1,6 +1,6 @@
 require 'json'
 require 'octokit'
-require_relative './merge_branch_service'
+require_relative './services/merge_branch_service'
 
 @event = JSON.parse(File.read(ENV['GITHUB_EVENT_PATH']))
 @head_to_merge = ENV['GITHUB_SHA'] # or brach name

lib/services/merge_branch_service.rb

@@ -1,5 +1,5 @@
-require_relative './labeled_adapter'
-require_relative './push_adapter'
+require_relative '../adapters/labeled_adapter'
+require_relative '../adapters/push_adapter'
 
 class MergeBrachService
 

spec/merge_brach_service_spec.rb

@@ -1,4 +1,4 @@
-require_relative '../lib/merge_branch_service'
+require_relative '../lib/services/merge_branch_service'
 
 describe MergeBrachService do
   context "with push" do