Adding units specification to mem_limit variable

Author: leonidlm

README.md

@@ -81,6 +81,8 @@ more information on how to create port bindings and volume mappings.
 The `environment` variable accepts a dictionary or a list of strings
 in the following format `["PASSWORD=xxx"]` or `{"PASSWORD": "xxx"}`.
 
+The `mem_limit` variable accepts float values (which represent the memory limit of the created container in bytes) or a string with a units identification char ('1000k', 128m', '1g').
+
 `volumes_from` and `dns` arguments raise TypeError exception if they are used
 against v1.10 of docker remote API. Those arguments should be passed to
 `start()` instead.

docker/client.py

@@ -111,6 +111,14 @@ def _container_config(self, image, command, hostname=None, user=None,
                 '{0}={1}'.format(k, v) for k, v in environment.items()
             ]
 
+        if isinstance(mem_limit, six.string_types):
+            units = {'k': 1024,
+                     'm': 1024*1024,
+                     'g': 1024*1024*1024}
+            suffix = mem_limit[-1].lower()
+            if suffix in units.keys():
+                mem_limit = int(mem_limit[:-1]) * units[suffix]
+
         if isinstance(ports, list):
             exposed_ports = {}
             for port_definition in ports: