Add working --last-used-mac

{'create_vm': False, 'last_used_mac': True, 'get_new_mac': False, 'debug': False, 'conf_dir': '/home/nico/uncloud', 'etcd_host': 'etcd1.ungleich.ch', 'etcd_port': None, 'etcd_ca_cert': '/home/nico/vcs/ungleich-dot-cdist/files/etcd/ca.pem', 'etcd_cert_cert': '/home/nico/vcs/ungleich-dot-cdist/files/etcd/nico.pem', 'etcd_cert_key': '/home/nico/vcs/ungleich-dot-cdist/files/etcd/nico-key.pem'}
00:20:00:00:00:00
(venv) [19:02] diamond:uncloud% ./bin/uncloud-run-reinstall hack  --etcd-host etcd1.ungleich.ch --etcd-ca-cert /home/nico/vcs/ungleich-dot-cdist/files/etcd/ca.pem --etcd-cert-cert /home/nico/vcs/ungleich-dot-cdist/files/etcd/nico.pem --etcd-cert-key /home/nico/vcs/ungleich-dot-cdist/files/etcd/nico-key.pem --last-used-mac

uncloud/hack/db.py

@@ -22,30 +22,75 @@
 
 import etcd3
 import json
+import logging
+
+from functools import wraps
+from uncloud import UncloudException
+
+log = logging.getLogger(__name__)
+
+
+def readable_errors(func):
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+        try:
+            return func(*args, **kwargs)
+        except etcd3.exceptions.ConnectionFailedError as e:
+            raise UncloudException('Cannot connect to etcd: is etcd running and reachable? {}'.format(e))
+        except etcd3.exceptions.ConnectionTimeoutError as e:
+            raise UncloudException('etcd connection timeout. {}'.format(e))
+
+    return wrapper
+
 
 class DB(object):
-    def __init__(self, config):
+    def __init__(self, config, prefix="/"):
         self.config = config
-        self.prefix= '/nicohack/'
+
+        # Root for everything
+        self.base_prefix= '/nicohack'
+
+        # Can be set from outside
+        self.prefix = prefix
+
         self.connect()
 
+    @readable_errors
     def connect(self):
         self._db_clients = []
         for endpoint in self.config.etcd_hosts:
             client = etcd3.client(host=endpoint, **self.config.etcd_args)
             self._db_clients.append(client)
 
-    def get_value(self, key):
-        pass
+    def realkey(self, key):
+        return "{}{}/{}".format(self.base_prefix,
+                                self.prefix,
+                                key)
 
-    def set(self, key, value, store_as_json=False, **kwargs):
-        if store_as_json:
+    @readable_errors
+    def get(self, key, as_json=False, **kwargs):
+        value, _ = self._db_clients[0].get(self.realkey(key), **kwargs)
+
+        if as_json:
+            value = json.loads(value)
+
+        return value
+
+
+    @readable_errors
+    def set(self, key, value, as_json=False, **kwargs):
+        if as_json:
             value = json.dumps(value)
 
-        key = "{}/{}".format(self.prefix, key)
-
         # FIXME: iterate over clients in case of failure ?
-        return self._db_clients[0].put(key, value, **kwargs)
+        return self._db_clients[0].put(self.realkey(key), value, **kwargs)
+
+    @readable_errors
+    def increment(key, **kwargs):
+        with self._db_clients[0].lock(key) as lock:
+            value = int(self.get(self.realkey(key), **kwargs))
+            self.set(self.realkey(key), str(value + 1), **kwargs)
+
 
 if __name__ == '__main__':
     endpoints = [ "https://etcd1.ungleich.ch:2379",