docker-service-reporter-lib/etcdlib.py

#!/usr/bin/env python3

import etcd
import time


class Connection:


  def __init__(self, host, port, prefix):
    self._client = etcd.Client(host=host, port=port)
    self._prefix = prefix


  def _read(self, key, **kwargs):
    try:
      node = self._client.read(self._prefix + key, **kwargs)
      return node.value if node else None
    except etcd.EtcdKeyNotFound:
      return None


  def _read_recursive(self, key):
    try:
      return self._client.read(self._prefix + key, recursive=True)
    except etcd.EtcdKeyNotFound:
      return None 


  def _write(self, key, value):
    self._client.write(self._prefix + key, value)


  def _write_obj(self, prefix, obj):
    for key, value in obj.items():
      new_prefix = "%s/%s" % (prefix, key)

      if isinstance(value, dict):
        self._write_obj(new_prefix, value)
      else:
        self._write(new_prefix, str(value))


  def _delete(self, key):
    try:
      self._client.delete(self._prefix + key, recursive=True)
    except etcd.EtcdKeyNotFound:
      pass


  def wipe(self):
    self._delete('')


  def add_containers(self, new_containers):
    for container in new_containers:
      name = container['name']
      print('Adding container %s' % name)
      self._write_obj('/containers/%s' % name, container)
      for k, v in container['labels'].items():
        self._write('/labels/%s/%s' % (k, name), v)
      for k, v in container['net']['addr'].items():
        self._write('/networks/%s/%s' % (k, name), v)
      self._write('/hosts/%s/%s' % (container['host'], name), name)
    self._notify_update()


  def remove_containers(self, old_containers):
    for container in old_containers:
      name = container['name']
      print('Removing container %s' % name)
      self._delete('/containers/%s' % name)
      for k, v in container['labels'].items():
        self._delete('/labels/%s/%s' % (k, name))
      for k, v in container['net']['addr'].items():
        self._delete('/networks/%s/%s' % (k, name)) 
      self._delete('/hosts/%s/%s' % (container['host'], name))
    self._notify_update()


  def get_label(self, label):
    node = self._read_recursive('/labels/%s' % label)
    if node:
      return {child.key.split('/')[-1]: child.value for child in node.children}
    else:
      return {}


  def _notify_update(self):
    print('Update completed', flush=True)
    self._write('/_updated', time.time())


  def wait_for_update(self):
    original_time = self._read('/_updated')
    new_time = original_time

    while new_time == original_time:
      try:
        new_time = self._read('/_updated', wait=True)
      except etcd.EtcdWatchTimedOut:
        new_time = self._read('/_updated')
      time.sleep(10)