docker-aufs-fsck.rb

#/ Usage: sudo ruby docker-aufs-fsck.rb
#/ Your docker aufs storage will be checked for orphaned or missing layers.

def main
  aufs_root = find_aufs_root
  die "Could not find aufs root!" if aufs_root.nil?

  fsck = Fsck.new({
    :images => `docker images -a -q --no-trunc`.split(/\s+/),
    :containers => `docker ps -a -q --no-trunc`.split(/\s+/),
  })
  Dir.chdir(aufs_root) do
    Subdirs.each do |dir|
      Dir.new(dir).each do |id|
        next if id == "." || id == ".."
        fsck.scan(id)
      end
    end
  end
  fsck.each_error do |error|
    puts error
  end
end

Subdirs = %w(layers diff mnt)

class Fsck
  def initialize(options)
    @tracked = options
    @processed = {}
    @graph = {}
    @graph_errors = []
  end

  def scan(id)
    load_graph(id)
    @processed[id] ||= {
      :missing_files => Subdirs.select { |subdir| ! File.exist?(File.join(subdir, id)) },
    }
  end

  def each_error
    @graph_errors.each do |error|
      yield error
    end
    @processed.each do |id, info|
      if info[:missing_files].any?
        yield "#{id}: Missing #{info[:missing_files].join(", ")}"
      end
    end
    @tracked.each do |type, ids|
      # type should be :images or :containers
      ids.each do |id|
        if !@processed[id]
          yield "#{type} #{id}: not in storage!"
        end
        if !@graph[id]
          yield "#{type} #{id}: not in the graph!"
        else
          @graph[id][:is] = type
        end
      end
    end
    @graph.each do |id, node|
      if node[:tip] && !node[:is]
        yield "#{id}: Not reachable from any image or container!"
      end
    end
  end

  private

  def load_graph(id)
    layers = File.read(File.join("layers", id)).lines.map(&:strip)
    # inject is designed for neckbeards
    layers.inject(@graph[id] ||= {:id => id, :tip => true}) do |cur_node, next_id|
      cur_node[:next] ||= next_id
      if cur_node[:next] != next_id
        @graph_errors << "layers/#{id}: #{cur_node[:id]} -> #{cur_node[:next]} AND #{next_id}"
      end
      (@graph[next_id] ||= {:id => next_id}).tap { |node| node[:tip] = false }
    end
  end
end

def find_aufs_root
  docker_info = `docker info`
  docker_info =~ /Storage Driver: aufs/ and
    docker_info =~ /^ Root Dir: (.*)/ and
    $1
end

def die(message)
  puts message
  exit 1
end

main