dockerjob.py

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"""Helpers to run docker instances as jobs."""

from __future__ import print_function

import jobset
import tempfile
import time
import uuid
import os
import subprocess

_DEVNULL = open(os.devnull, 'w')


def random_name(base_name):
  """Randomizes given base name."""
  return '%s_%s' % (base_name, uuid.uuid4())


def docker_kill(cid):
  """Kills a docker container. Returns True if successful."""
  return subprocess.call(['docker','kill', str(cid)],
                         stdin=subprocess.PIPE,
                         stdout=_DEVNULL,
                         stderr=subprocess.STDOUT) == 0


def docker_mapped_port(cid, port, timeout_seconds=15):
  """Get port mapped to internal given internal port for given container."""
  started = time.time()
  while time.time() - started < timeout_seconds:
    try:
      output = subprocess.check_output('docker port %s %s' % (cid, port),
                                       stderr=_DEVNULL,
                                       shell=True)
      return int(output.split(':', 2)[1])
    except subprocess.CalledProcessError as e:
      pass
  raise Exception('Failed to get exposed port %s for container %s.' %
                  (port, cid))


def finish_jobs(jobs):
  """Kills given docker containers and waits for corresponding jobs to finish"""
  for job in jobs:
    job.kill(suppress_failure=True)

  while any(job.is_running() for job in jobs):
    time.sleep(1)


def image_exists(image):
  """Returns True if given docker image exists."""
  return subprocess.call(['docker','inspect', image],
                         stdin=subprocess.PIPE,
                         stdout=_DEVNULL,
                         stderr=subprocess.STDOUT) == 0


def remove_image(image, skip_nonexistent=False, max_retries=10):
  """Attempts to remove docker image with retries."""
  if skip_nonexistent and not image_exists(image):
    return True
  for attempt in range(0, max_retries):
    if subprocess.call(['docker','rmi', '-f', image],
                       stdin=subprocess.PIPE,
                       stdout=_DEVNULL,
                       stderr=subprocess.STDOUT) == 0:
      return True
    time.sleep(2)
  print('Failed to remove docker image %s' % image)
  return False


class DockerJob:
  """Encapsulates a job"""

  def __init__(self, spec):
    self._spec = spec
    self._job = jobset.Job(spec, newline_on_success=True, travis=True, add_env={})
    self._container_name = spec.container_name

  def mapped_port(self, port):
    return docker_mapped_port(self._container_name, port)

  def kill(self, suppress_failure=False):
    """Sends kill signal to the container."""
    if suppress_failure:
      self._job.suppress_failure_message()
    return docker_kill(self._container_name)

  def is_running(self):
    """Polls a job and returns True if given job is still running."""
    return self._job.state() == jobset._RUNNING