Wait for updates and run in a loop.

README.md

@@ -49,8 +49,3 @@ docker run -d \
   --<arguments>
 ```
 
-## Current known issues
-
-* **The container performs one update and then exits.** It does not yet monitor
-  for changes to etcd.
-

fetcher.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 
 import etcd
+import time
 
 
 class Fetcher:
@@ -19,5 +20,20 @@ class Fetcher:
 
   def get_label(self, label):
     node = self._read_recursive('/labels/%s' % label)
-    return {child.key.split('/')[-1]: child.value for child in node.children}
+    if node:
+      return {child.key.split('/')[-1]: child.value for child in node.children}
+    else:
+      return {}
+
+
+  def wait_for_update(self):
+    original_time = self._client.read(self._prefix + '/_updated').value
+    new_time = original_time
+
+    while new_time == original_time:
+      try:
+        new_time = self._client.read(self._prefix + '/_updated', wait=True).value
+      except etcd.EtcdWatchTimedOut:
+        new_time = self._client.read(self._prefix + '/_updated').value
+      time.sleep(10)
 

generate.py

@@ -12,23 +12,30 @@ parser.add_argument('--etcd-host', help='Host to connect to etcd on', default='e
 parser.add_argument('--etcd-prefix', help='Prefix to use when retrieving keys from etcd', default='/docker')
 args = parser.parse_args()
 
-domains = defaultdict(set)
 fetcher = Fetcher(args.etcd_host, args.etcd_port, args.etcd_prefix)
-for container, values in fetcher.get_label('com.chameth.vhost').items():
-  parts = values.split(',')
-  domains[parts[0].strip()] |= set([] if len(parts) == 1 else parts[1:])
-
-with open('/letsencrypt/domains.txt.new', 'w') as f:
-  for domain, alts in domains.items():
-    f.write(domain)
-    if len(alts):
-      f.write(' ' + ' ' .join(alts))
-    f.write('\n')
-
-try:
-  os.remove('/letsencrypt/domains.txt')
-except OSError:
-  pass
-
-os.rename('/letsencrypt/domains.txt.new', '/letsencrypt/domains.txt')
+
+while True:
+  domains = defaultdict(set)
+  for container, values in fetcher.get_label('com.chameth.vhost').items():
+    parts = values.split(',')
+    domains[parts[0].strip()] |= set([] if len(parts) == 1 else parts[1:])
+
+  with open('/letsencrypt/domains.txt.new', 'w') as f:
+    print('Writing domains.txt...')
+    for domain, alts in domains.items():
+      print('%s [%s]' % (domain, ', '.join(alts)))
+      f.write(domain)
+      if len(alts):
+        f.write(' ' + ' ' .join(alts))
+      f.write('\n')
+
+  try:
+    os.remove('/letsencrypt/domains.txt')
+  except OSError:
+    pass
+
+  os.rename('/letsencrypt/domains.txt.new', '/letsencrypt/domains.txt')
+  print('Done writing domains.txt')
+
+  fetcher.wait_for_update()