Initial version

Dockerfile

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+FROM python:3.5.1-alpine 
+MAINTAINER Chris Smith <chris87@gmail.com> 
+
+RUN \
+  pip install \
+    python-etcd==0.4.3
+
+COPY etcdlib.py /

README.md

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+# Docker service reporter library 
+
+This is a docker image intended as a base layer for things interacting with my
+[service reporter container](https://github.com/csmith/docker-service-reporter).
+
+It provides a python library for interacting with etcd, with convenience
+functions for retrieving the higher-level data structures (such as containers
+and labels) that the reporter service creates.
+

etcdlib.py

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+#!/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)
+