Class: RightScraper::Processes::SSHAgent

Inherits:
Object
  • Object
show all
Defined in:
lib/right_scraper/processes/ssh.rb

Overview

Manage a dedicated SSH agent.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ SSHAgent

Returns a new instance of SSHAgent.



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# File 'lib/right_scraper/processes/ssh.rb', line 31

def initialize
  @display = ENV['DISPLAY']
  @askpass = ENV['SSH_ASKPASS']
  @sshauth = ENV['SSH_AUTH_SOCK']
  @agentpid = ENV['SSH_AGENT_PID']
  @home = ENV['HOME']
end

Class Method Details

.with ⇒ Object

Execute the block in a new ssh agent. Equivalent to

agent = SSHAgent.new
begin
 agent.open
 ...
ensure
 agent.close
end



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# File 'lib/right_scraper/processes/ssh.rb', line 177

def self.with
  agent = SSHAgent.new
  begin
    agent.open
    yield agent
  ensure
    agent.close
  end
end

Instance Method Details

#add_key(key) ⇒ Object

Add the given key data to the ssh agent.

Parameters

key(String)

ssh key data



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# File 'lib/right_scraper/processes/ssh.rb', line 148

def add_key(key)
  begin
    file = Tempfile.new('key')
    file.puts(key)
    file.close

    add_keyfile(file.path)
  ensure
    file.close(true) unless file.nil?
  end
end

#add_keyfile(file) ⇒ Object

Add the key data in the given file to the ssh agent.

Parameters

file(String)

file containing key data



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# File 'lib/right_scraper/processes/ssh.rb', line 164

def add_keyfile(file)
  ProcessWatcher.watch("ssh-add", [file], nil, -1, 10)
end

#close ⇒ Object

Close the connection to the SSH agent, and restore ENV.



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# File 'lib/right_scraper/processes/ssh.rb', line 64

def close
  begin
    FileUtils.remove_entry_secure @dir
    lay_to_rest(@pid) if @pid
    @monitor.cleanup if @monitor
  ensure
    setvar 'SSH_AGENT_PID', @agentpid
    setvar 'DISPLAY', @display
    setvar 'SSH_ASKPASS', @askpass
    setvar 'SSH_AUTH_SOCK', @sshauth
    setvar 'HOME', @home
  end
end

#lay_to_rest(pid, timeout = 10) ⇒ Object

Kill pid. Initially use SIGTERM to be kind and a good citizen. If it doesn’t die after timeout seconds, use SIGKILL instead. In any case, the process will die. The status information is accessible in $?.

Parameters

pid(Fixnum)

pid of process to kill

timeout(Fixnum)

time in seconds to wait before forcing process to die. Defaults to 10 seconds.



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# File 'lib/right_scraper/processes/ssh.rb', line 87

def lay_to_rest(pid, timeout=10)
  #refuse to kill ourselves, or to pass a bad arg to Process.kill
  return 0 unless pid.is_a?(Integer) && pid > 0

  Process.kill('TERM', pid)
  time_waited = 0
  loop do
    if time_waited >= timeout
      Process.kill('KILL', pid)
      # can't waitpid here, because the ssh-agent isn't our
      # child.  Still, after SIGKILL it will die and init will
      # reap it, so continue
      return
    end
    # still can't waitpid here, so we see if it's still alive
    return unless still_alive?(pid)
    sleep 1
    time_waited += 1
  end
end

#open ⇒ Object

Open a connection to the SSH agent and set ENV appropriately.



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# File 'lib/right_scraper/processes/ssh.rb', line 41

def open
  ENV['SSH_ASKPASS'] = File.expand_path(File.join(File.dirname(__FILE__),
                                                  '..', '..', '..',
                                                  'scripts',
                                                  'stub_ssh_askpass'))
  ENV['HOME'] = "/dev/null"
  @dir = Dir.mktmpdir
  @socketfile = File.join(@dir, "agent")
  @monitor = ProcessWatcher::ProcessMonitor.new
  @pid = @monitor.spawn('ssh-agent', '-a', @socketfile, '-d') {}
  timeout = 0
  until File.exists?(@socketfile)
    timeout += 1
    sleep 0.1
    if timeout > 100
      raise "Couldn't find SSH agent control socket in time.  Timing out"
    end
  end
  ENV['SSH_AGENT_PID'] = @pid.to_s
  ENV['SSH_AUTH_SOCK'] = @socketfile
end

#still_alive?(pid) ⇒ Boolean

Check to see if the process pid is still alive, by sending the 0 signal and checking for an exception.

Parameters

pid(Fixnum)

pid of process to check on

Return

Boolean

true if process is still alive

Returns:

  • (Boolean) 


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# File 'lib/right_scraper/processes/ssh.rb', line 116

def still_alive?(pid)
  begin
    Process.kill(0, pid)
    true
  rescue Errno::ESRCH
    false
  end
end