Class: LinuxContainer

Inherits:
Object
  • Object
show all
Defined in:
lib/linux_container.rb

Defined Under Namespace

Classes: ProcessFailed

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(params = {}) ⇒ LinuxContainer

Returns a new instance of LinuxContainer.



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# File 'lib/linux_container.rb', line 20

def initialize(params={})
  params.each {|k,v| instance_variable_set "@#{k}", v }
  @username ||= 'ubuntu'
end

Instance Attribute Details

#ip ⇒ Object 



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# File 'lib/linux_container.rb', line 30

def ip
  @ip ||= self.class.get_ip_for(name)
end

#name ⇒ Object

Returns the value of attribute name.



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# File 'lib/linux_container.rb', line 7

def name
  @name
end

#ssh_key_path ⇒ Object

Returns the value of attribute ssh_key_path.



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# File 'lib/linux_container.rb', line 7

def ssh_key_path
  @ssh_key_path
end

#username ⇒ Object

Returns the value of attribute username.



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# File 'lib/linux_container.rb', line 7

def username
  @username
end

Class Method Details

.all ⇒ Object 



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# File 'lib/linux_container.rb', line 10

def self.all
  `#{sudo_if_needed} lxc-ls -1`.lines.map(&:strip).uniq.map {|cname| new(name: cname) }
end

.get_ip_for(name) ⇒ Object 



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# File 'lib/linux_container.rb', line 156

def self.get_ip_for(name)
  fn = ['/var/lib/misc/dnsmasq.lxcbr0.leases', '/var/lib/misc/dnsmasq.leases'].detect {|f| File.readable?(f) }
  File.read(fn).each_line do |line|
    (timestamp,macaddr,ip,hostname,misc) = line.split(' ')
    return ip if hostname == name
  end
  nil
end

.sudo_if_needed ⇒ Object 



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# File 'lib/linux_container.rb', line 165

def self.sudo_if_needed
  'sudo' unless Process.uid == 0
end

.version ⇒ Object 



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# File 'lib/linux_container.rb', line 14

def self.version
  @version ||= if `lxc-version` =~ /version: (\d+\.\d+)\./i
    $1
  end
end

Instance Method Details

#bg_execute(*cmd) ⇒ Object

Raises:



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# File 'lib/linux_container.rb', line 143

def bg_execute(*cmd)
  logfile_path = "/tmp/lxc_ephemeral_#{Time.now.to_i.to_s(36)}#{$$}#{rand(0x100000000).to_s(36)}.log"
  cmdstring = "#{self.class.sudo_if_needed} #{cmd.shift} #{Shellwords.join(cmd)} >>#{logfile_path} 2>>#{logfile_path}"
  pid = spawn(cmdstring, pgroup: true)
  raise ProcessFailed.new("command failed: #{cmdstring.inspect}") unless pid > 0
  Thread.abort_on_exception = true
  Thread.new do 
    Process.waitpid pid
    raise ProcessFailed.new("command failed: #{cmdstring.inspect}") unless $? == 0
  end
  logfile_path
end

#clone_from(from, *args) ⇒ Object 



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# File 'lib/linux_container.rb', line 43

def clone_from(from, *args)
  fromname = self.class === from ? from.name : from
  lxc_execute('clone', '-o',fromname, *args)
end

#create(config = {}) ⇒ Object

template, hostid, userdata, auth-key, arch, release



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# File 'lib/linux_container.rb', line 34

def create(config={})  # template, hostid, userdata, auth-key, arch, release
  args = (ssh_key_path ? {'auth-key' => "#{ssh_key_path}.pub"} : {}).merge(config).map {|k, v| "--#{k}=#{v}" }
  lxc_execute('create', '-t', config.delete(:template) || 'ubuntu-cloud', '--', *args)
end

#dir(subdir = nil) ⇒ Object 



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# File 'lib/linux_container.rb', line 102

def dir(subdir=nil)
  "/var/lib/lxc/#{name}/rootfs/#{subdir}"
end

#execute(*cmd) ⇒ Object 



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# File 'lib/linux_container.rb', line 128

def execute(*cmd)
  cmdstring = "#{self.class.sudo_if_needed} #{cmd.shift} #{Shellwords.join(cmd)}"
  result = ''
  IO.popen("#{cmdstring} 2>&1", 'r') do |io|
    io.each_line do |line|
      yield line if block_given?
      result << line
    end
  end
  raise "command failed: #{cmdstring.inspect}\n#{result}" unless $? == 0
  result
end

#lxc_execute(cmd, *args) ⇒ Object 



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# File 'lib/linux_container.rb', line 124

def lxc_execute(cmd, *args)
  execute("lxc-#{cmd}", '-n', name, *args)
end

#parent_container ⇒ Object 



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# File 'lib/linux_container.rb', line 48

def parent_container
  n = name.dup
  self.class.new(name: n) if n.sub!(/(-temp)?-[0-9A-Za-z_\-]+$/, '')
end

#running? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/linux_container.rb', line 98

def running?
  state == 'RUNNING'
end

#scp_from(srcpath, dstpath, *args) ⇒ Object 



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# File 'lib/linux_container.rb', line 82

def scp_from(srcpath, dstpath, *args)
  execute('scp', *args, *ssh_args, "#{username}@#{ip}:#{srcpath}", dstpath)
end

#scp_to(srcpath, dstpath, *args) ⇒ Object 



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# File 'lib/linux_container.rb', line 78

def scp_to(srcpath, dstpath, *args)
  execute('scp', *args, *ssh_args, srcpath, "#{username}@#{ip}:#{dstpath}")
end

#ssh(cmd, &bl) ⇒ Object 



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# File 'lib/linux_container.rb', line 74

def ssh(cmd, &bl)
  execute('ssh', *ssh_args, "#{username}@#{ip}", cmd, &bl)
end

#ssh_args ⇒ Object 



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# File 'lib/linux_container.rb', line 86

def ssh_args
  raise "cannot ssh without ip" unless ip
  args = ['-o','StrictHostKeyChecking=no','-o','UserKnownHostsFile=/dev/null','-q']
  args.push('-i', ssh_key_path) if ssh_key_path
  args
end

#sshable? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/linux_container.rb', line 94

def sshable?
  ssh('true') rescue false
end

#start_ephemeral(config = {}) ⇒ Object 



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# File 'lib/linux_container.rb', line 53

def start_ephemeral(config={})
  argshash = {'orig' => name, 'user' => username}.merge!(config)
  args = []
  if self.class.version == '0.8' # ubuntu quantal and older
    argshash['union-type'] ||= 'aufs'
    args.push '-U', argshash.delete('union-type')
  else # ubuntu raring and newer
    argshash['union-type'] ||= 'overlayfs'
    args << '-d'
  end
  args.push *argshash.map {|k, v| "--#{k}=#{v}" }
  
  logfile_path = bg_execute('lxc-start-ephemeral', *args)
  newname = nil
  while newname.nil?
    sleep 1
    newname = $1 || $2 if File.read(logfile_path) =~ /^(.*) is running|lxc-console -n (.*)$/
   end
  self.class.new(name: newname, ssh_key_path: ssh_key_path, username: username)
end

#state ⇒ Object 



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# File 'lib/linux_container.rb', line 25

def state
  res = `#{self.class.sudo_if_needed} lxc-info -n #{Shellwords.escape name} -s 2>&1`
  res.chomp.split(':').last.to_s.strip 
end

#wait_for(timeout = 300, interval = 1, &block) ⇒ Object 



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# File 'lib/linux_container.rb', line 106

def wait_for(timeout=300, interval=1, &block)
  Timeout.timeout(timeout) do
    duration = 0
    start = Time.now
    until instance_eval(&block) || duration > timeout
      sleep(interval.to_f)
      duration = Time.now - start
    end
    if duration > timeout
      false
    else
      duration
    end
  end
end