preflight script for docker upgrade from 17.03.0-ce to 17.06.0-ce

preflight-docker-upgrade.rb

#!/usr/bin/env ruby
# pre-flight script for docker upgrade from 17.03.0-ce to 17.06.0-ce
# Issue: https://github.com/docker/for-linux/issues/49

require 'json'

module JSON
  def self.load_file(path)
    parse File.read(path)
  end
end

Dir.glob('/run/runc/*/state.json') do |file|
  data = JSON.load_file(file)
  if data['config']['cgroups']['memory_swappiness'] == -1
    data['config']['cgroups']['memory_swappiness'] = nil
    File.write file, data.to_json
  end
end

Dir.glob('/run/docker/libcontainerd/*/config.json') do |file|
  data = JSON.load_file(file)
  data['process']['capabilities'] = if data['process']['capabilities'].respond_to?(:flatten)
    %w{bounding effective inheritable permitted}.inject({}) do |memo, key|
      memo.merge!({ key => data['process']['capabilities'] })
    end
    File.write file, data.to_json
  end
end

Dir.glob('/run/docker/libcontainerd/containerd/*/init/process.json') do |file|
  data = JSON.load_file(file)
  data['capabilities'] = if data['capabilities'].respond_to?(:flatten)
    %w{bounding effective inheritable permitted}.inject({}) do |memo, key|
      memo.merge!({ key => data['capabilities'] })
    end
    File.write file, data.to_json
  end
end