docker compose build のメモリ容量不足の対策

こちら参照。
https://kazmax.zpp.jp/linux_beginner/mkswap.html

解決策　swap領域を追加し、bundle installを可能にする。

以下エラー文。

Installing nokogiri 1.10.10 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: /usr/local/bundle/gems/nokogiri-1.10.10/ext/nokogiri
/usr/local/bin/ruby -r ./siteconf20201104-6-1o7c1oy.rb extconf.rb
Cannot allocate memory - /usr/local/bin/ruby -r ./siteconf20201104-6-1o7c1oy.rb
extconf.rb 2>&1

Gem files will remain installed in /usr/local/bundle/gems/nokogiri-1.10.10 for
inspection.
Results logged to
/usr/local/bundle/extensions/x86_64-linux/2.5.0/nokogiri-1.10.10/gem_make.out

An error occurred while installing nokogiri (1.10.10), and Bundler cannot

continue.
Make sure that `gem install nokogiri -v '1.10.10' --source
'https://rubygems.org/'` succeeds before bundling.

In Gemfile:
  rails was resolved to 5.2.4.4, which depends on
    actioncable was resolved to 5.2.4.4, which depends on
      actionpack was resolved to 5.2.4.4, which depends on
        actionview was resolved to 5.2.4.4, which depends on
          rails-dom-testing was resolved to 2.0.3, which depends on
            nokogiri
ERROR: Service 'app' failed to build: The command '/bin/sh -c bundle install' returned a non-zero code: 5