chore: add release and continuous/post kokoro jobs (#836)

Rakefile

@@ -1,4 +1,51 @@
 require "bundler/gem_tasks"
+require "json"
+
+task :release_gem, :tag do |_t, args|
+  tag = args[:tag]
+  raise "You must provide a tag to release." if tag.nil?
+
+  # Verify the tag format "vVERSION"
+  m = tag.match(/v(?<version>\S*)/)
+  raise "Tag #{tag} does not match the expected format." if m.nil?
+
+  version = m[:version]
+  raise "You must provide a version." if version.nil?
+
+  api_token = ENV["RUBYGEMS_API_TOKEN"]
+
+  require "gems"
+  if api_token
+    ::Gems.configure do |config|
+      config.key = api_token
+    end
+  end
+
+  Bundler.with_clean_env do
+    sh "rm -rf pkg"
+    sh "bundle update"
+    sh "bundle exec rake build"
+  end
+
+  path_to_be_pushed = "pkg/google-api-client-#{version}.gem"
+  gem_was_published = nil
+  if File.file? path_to_be_pushed
+    begin
+      response = ::Gems.push File.new(path_to_be_pushed)
+      puts response
+      raise unless response.include? "Successfully registered gem:"
+      gem_was_published = true
+      puts "Successfully built and pushed google-api-client for version #{version}"
+    rescue StandardError => e
+      gem_was_published = false
+      puts "Error while releasing google-api-client version #{version}: #{e.message}"
+    end
+  else
+    raise "Cannot build google-api-client for version #{version}"
+  end
+
+  Rake::Task["kokoro:publish_docs"].invoke if gem_was_published
+end
 
 task default: :spec
 
@@ -22,13 +69,35 @@ namespace :kokoro do
   task :nightly do
     Rake::Task["spec"].invoke
   end
+
+  task :post do
+    require_relative "rakelib/link_checker.rb"
+
+    link_checker = LinkChecker.new
+    link_checker.run
+    exit link_checker.exit_status
+  end
+
+  task :release do
+    # Until code generation process is updated and release-please is set up, just publish docs
+    require_relative "rakelib/devsite/devsite_builder.rb"
+
+    DevsiteBuilder.new.publish_if_missing ENV["DOCS_BUILD_TAG"]
+  end
+
+  desc "Publish docs for the latest git tag"
+  task :publish_docs do
+    require_relative "rakelib/devsite/devsite_builder.rb"
+
+    DevsiteBuilder.new.publish ENV["DOCS_BUILD_TAG"]
+  end
 end
 
 def header str, token = "#"
   line_length = str.length + 8
-  puts ""
+  puts
   puts token * line_length
   puts "#{token * 3} #{str} #{token * 3}"
   puts token * line_length
-  puts ""
+  puts
 end